WET-TYPE END PART SEAL MATERIAL FOR LINEAR MOTION MECHANISM, AND LINEAR MOTION MECHANISM USING SAME

Abstract

To provide an end portion sealing member for a linear motion mechanism having good lubrication characteristics and a high degree of protection against dust. An end portion seal member capable of being attached at either end of slider in linear motion mechanism comprising rail and slider, wherein said end portion seal member has support frame body arranged at an outside circumference of said rail; base fabric portion, the back surface of which is secured to an inside circumferential surface of said support frame body; and cut pile that protrudes from a front surface of said base fabric portion; wherein fiber tip portions of said cut pile are bent and made to abut the rail in such fashion as to occlude a gap between said rail and said support frame body; and lubricant has been made to be retained in advance in spaces between pile fibers of said cut pile.

Claims

1. A wet end portion seal member comprising cut pile characterized in that the end portion seal member is capable of being attached at either end of a slider in a linear motion mechanism comprising a rail and the slider, wherein said end portion seal member has a support frame body arranged at an outside circumference of said rail; a base fabric portion, a back surface of which is secured to an inside circumferential surface of said support frame body; and the cut pile that protrudes from a front surface of said base fabric portion; wherein fiber tip portions of said cut pile are bent and made to abut the rail in such fashion as to occlude a gap between said rail and said support frame body; and a lubricant has been made to be retained in advance in spaces between pile fibers of said cut pile.

2. The end portion seal member according to claim 1 characterized in that the lubricant retained in the spaces between the pile fibers of the cut pile is grease for which a grade number as defined at JIS K2220 is No. 1 to No. 4.

3. The end portion seal member according to claim 2 characterized in that the grease is any among lithium grease, grease in which molybdenum compound has been blended, and urea-type grease.

4. The end portion seal member according to claim 1 characterized in that pile length of the cut pile is not less than 2 mm.

5. The end portion seal member according to claim 1 characterized in that the pile fibers of the cut pile consist of crimped multifilament fiber.

6. The end portion seal member according to claim 1 characterized in that the cut pile comprises woven fabric.

7. The end portion seal member according to claim 1 characterized in that the cut pile comprises knit fabric.

8. The linear motion mechanism comprising a rail and a slider wherein the end portion seal member according to claim 1 is secured to either end of the slider in such fashion as to permit replacement to be accomplished by carrying out removal and attachment thereof.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0038] FIG. 1 Reactive-force-providing load curves indicating relationship between reactive-force-providing load (go and gap (mm) when felt or B-type or C-type pile is used.

[0039] FIG. 2 Drawing illustrating an embodiment of an end portion seal member that might be employed where a gap to be filled includes a curved surface. Shown is a procedure for causing a plate to be inserted in and secured to support frame bodies in such fashion as to prevent a wet sealing member from coming free from the support frame bodies after the wet sealing member which has grease-containing pile is rotated as it is inserted therein and caused to be arranged in helically opposed fashion with respect to the groove of a ball screw for a length permitting one or two turns at a location such as will cause it to be arranged in helically opposed fashion with respect to the groove of the ball screw in one of a pair of split support frame bodies that will be arranged about the outside circumference of the male-threaded shaft of the ball screw and the other of the pair of split support frame bodies is mated therewith.

[0040] FIG. 3 Drawing illustrating an embodiment of an end portion seal member that might be employed where a gap to be filled includes a curved surface. Shown is a procedure for causing a plate to be inserted in and secured to a support frame body in such fashion as to prevent a wet sealing member from coming free from the support frame body after the wet sealing member which has grease-containing pile is inserted therein and caused to be arranged in helically opposed fashion with respect to the groove of a ball screw for a length permitting at least one to three turns at a location such as will cause it to be arranged in helically opposed fashion with respect to the groove of the ball screw in the support frame body that will be arranged about the outside circumference of the male-threaded shaft of the ball screw.

[0041] FIG. 4 Drawing illustrating an embodiment of an end portion seal member that might be employed where a gap to be filled includes a curved surface. Shown is a procedure for causing a split support frame body that will be arranged about the outside circumference of the male-threaded shaft of a ball screw to cover and be made integral with the ball screw at any desired location along the ball screw after a wet sealing member which has pile that contains a stripe-like arrangement of grease is caused to be arranged in opposed fashion at a location such as will cause it to be arranged so as to respectively helically oppose the peaks and troughs of the groove of the ball screw.

[0042] FIG. 5 Drawing illustrating an embodiment of an end portion seal member that might be employed where a gap to be filled includes a curved surface. Shown is a procedure for causing a grease-containing wet sealing member in which pile has been cut in stripe-like fashion so as to helically conform to the groove of a ball screw so as to permit it to be arranged in helically opposed fashion with respect to the groove of the ball screw for a length permitting not less than one turn to be inserted in and made integral with a support frame body that will be arranged about the outside circumference of the male-threaded shaft of the ball screw, in such fashion as to at least be arranged in helically opposed fashion with respect to the groove of the ball screw.

[0043] FIG. 6 Drawing illustrating how end portion seal members in accordance with the means of the present invention might be attached at either end of the slider in a linear motion mechanism comprising a rail and a slider.

[0044] FIG. 7 Drawing illustrating in schematic fashion a method by which end portion seal members in accordance with the means of the present invention might be attached at either end of the slider in a linear motion mechanism comprising a rail and a slider.

[0045] FIG. 8 Sectional view illustrating in schematic fashion how end portion seal members in accordance with the means of the present invention might be attached at either end of the slider in a linear motion mechanism comprising a rail and a slider. The slider moves to the left and right on the rail.

[0046] FIG. 9 Drawing illustrating in schematic fashion how end portion seal members in accordance with the means of the present invention might be attached at either end of the slider in a linear motion mechanism comprising a rail and a slider.

EMBODIMENTS FOR CARRYING OUT INVENTION

[0047] Below, embodiments of the present invention are described in concrete terms with reference as appropriate to the drawings and descriptions of working examples. FIG. 7, FIG. 8, and FIG. 9 show an embodiment of a linear motion mechanism in accordance with the present invention in the form of a linear motion mechanism 6 comprising a linear guide comprising a rail 7 and a slider 8. At this linear guide, at either end of slider 8, end portion seal member 9 in accordance with the means of the present invention is arranged so as to come in contact with the tips of cut pile 10 at the outside circumference of rail 7, end portion seal member 9 being covered by exterior casing 14, and exterior casing 14 being secured by screw 13 to slider 8.

[0048] End portion seal members 9 are arranged at the front end and back end of that portion of slider 8 which slides on rail 7. End portion seal member 9 is such that the back surface of base fabric portion 12 comes in contact with the inside circumferential surface of support frame body 11 which serves as outer frame, and innumerable strands of cut pile 10 from which fiber tips protrude are arranged at the front surface of base fabric portion 12. End portion seal members 9 are respectively secured at the ends of slider 8 which moves forward and backward; or, as viewed in FIG. 8, because slider 8 moves horizontally, i.e., to the left and right as seen in the drawing, end portion seal members 9 are arranged at the left and right ends of slider 8 as seen in FIG. 8. End portion seal members 9 are arranged in such fashion as to cause the tips of cut pile 10 to abut and make light contact with the surface of rail 7 so as to cover locations to the front and back of the region at which sliding between rail 7 and slider 8 occurs. That is, cut pile 10 acts as a seal to occlude the gap between rail 7 and slider 8.

[0049] At end portion seal 9 shown in FIG. 8, this may be such that the back surface of a base fabric portion at which cut pile protrudes from the front surface of the base fabric is affixed to one surface of a rectangular metal plate (e.g., an aluminum plate), this being capable of being folded and formed so as to cause the metal plate to be toward the exterior and the cut pile to be toward the interior in such fashion as to permit the tips of the cut pile to be made to conform to the cross-sectional shape of rail 7, as a result of which it will be possible to easily obtain an end portion seal 9 in accordance with the present invention in which cut pile 10 is arranged at the inside circumference of a C-shaped support frame body 11.

[0050] Grease or other such lubricant would have been made to be retained in advance in the spaces between the fibers of cut pile 10. Because end portion seal member 9 is therefore of the wet type, it permits use in such fashion as to provide good seal characteristics. Furthermore, because it is possible for lubricant component in the vicinity of the region toward the base fabric of the cut pile to wet the tips of cut pile 10, this permits supply thereof as appropriate to the abutting surface(s). Because lubricant component is therefore supplied naturally when sliding occurs with respect to rail 7, the structure is such as will tend to cause insufficient lubrication not to occur.

[0051] Moreover, because end portion seal member 9 is such that it is secured by way of exterior casing 14 by only screw 13, it is possible by loosening screw 13 secured to slider 8 and removing exterior casing 14 to easily cause end portion seal member 9 to be removed therefrom and to carry out replacement, cleaning, oiling, and/or other such maintenance operations.

[0052] Furthermore, while, for reasons related to the fact that testing employing a linear guide was carried out, the linear motion mechanism employed in the description below is such that design is given in terms of the representative example of a linear guide, because the content thereof is applicable to other linear motion mechanisms as well, such descriptions should not be interpreted as being limited to any particular embodiment of linear motion mechanism.

Exemplary Test 1: Determination of Grease Retention Characteristics and Grease Deliverability of Woven Pile Fabrics and Knit Pile Fabrics in Wet End Portion Seal Members for Linear Motion Mechanisms

Materials and Methods

Pile Subject to Evaluation

[0053] In carrying out evaluation of grease retention characteristics and seal characteristics of woven pile fabric and knit pile fabric in a wet end portion seal member for a linear motion mechanism, a total of five types of woven pile fabric and knit pile fabric were selected for use in said such wet end portion seal member. Details regarding the constitutions of the woven pile fabrics and knit pile fabric that were selected are shown in TABLE 1, below.

TABLE-US-00001 TABLE 1 Pile type P-type C-type G-type T-type B-type Pile properties Straight fiber Crimped Crimped (woven Crimped (woven Crimped (knit (woven fabric) (woven fabric) fabric) fabric) fabric) Number of rows of pile 1 1 1 2 1 2 1 Pile A PPS 150D 3.0 D Biosafe 3.0 D 3.0 D 3.0 D 0.5 D 1.5 D Acrylic constitution Biosafe Bulky Aquatry Belima B — 1.5 D Aqualon 1.5 D 3.0 D 1.5 D — 1.5 D Cotton Aqualon Regular Voidmax C — 1.5 D Rayon 1.5 D 1.5 D 1.5 D — — Rayon Rayon Rayon Density (fibers/inch.sup.2) 378,000 316,050 276,675 646,400 179,968 Base fabric Weft Nylon (33T-6F) Polyester Polyester (T 30/1) Polyester (T 30/1) Polyester constitution yarn Thermally fusible (T 30/1) (T 30/1) yarn (33T-6F) Warp Nylon (167T-8F) Polyester/Rayon Polyester/Rayon Polyester/Rayon Polyester/Rayon yarn (T/R 30/2) (T/R 30/2) (T/R 40/2) (T/R 40/2) Coating CM3200 CM4025 CM4025 CM4025 CM3200

[0054] The pile at the P-type woven pile fabric at TABLE 1 was such that the napped pile fibers therein employed one type of straight fiber. These were among those for which fiber diameter was largest among the woven pile fabrics and knit pile fabric that were selected. Density was 378,000 per square inch. In addition, the ground yarn portion of the base fabric to which the pile was secured was a double-woven fabric in which both the warp and the weft were double-woven and which comprised two layers, these being a front layer portion and a back layer portion, and which was a woven fabric in which there were weft yarns (nylon/thermally fusible yarn) and warp yarns (nylon). To reduce shedding of cut pile, the ground yarn portion of the base fabric was impregnated with an acrylic emulsion from the back side thereof.

[0055] The pile at the C-type woven pile fabric was crimped and employed hollow fibers and porous fibers, the napped pile fibers therein employing one type of mixed yarn containing 3.0-denier Biosafe, 1.5-denier Aqualon, and 1.5-denier rayon, density of which was 316,050 per square inch. In addition, the ground yarn portion of the base fabric to which the pile was secured was a double-woven fabric in which both the warp and the weft were double-woven and which comprised two layers, these being a front layer portion and a back layer portion, and which was a woven fabric in which there were weft yarns (polyester) and warp yarns (polyester/rayon). To reduce shedding of cut pile, the ground yarn portion of the base fabric was impregnated with an acrylic emulsion from the back side thereof. Due to the fact that hollow fibers and porous fibers were employed therein, surface area at the pile was greater than would have been the case had straight fibers of the same fiber diameters been employed.

[0056] Like the C-type woven pile fabric, the pile at the G-type woven pile fabric was crimped, but the crimped pile at the G-type woven pile fabric was such that half of the rows of pile were C-type pile that was crimped and that employed hollow fibers and porous fibers, while the remaining half of the rows of pile were crimped pile that employed ordinary fibers which were neither hollow nor porous. There were two types of napped pile fiber, the pile fibers being secured in alternating fashion one-type-at-a-time to the weft yarn of the ground yarn portion which constituted the base fabric. The pile in the first row was a mixed yarn containing 3.0-denier Biosafe, 1.5-denier Aqualon, and 1.5-denier rayon; the pile in the second row comprised a mixed yarn containing 3.0-denier bulky, 3.0-denier regular, and 1.5-denier rayon. Fiber density was 276,675. In addition, the ground yarn portion of the base fabric to which the pile was secured was a double-woven fabric in which both the warp and the weft were double-woven and which comprised two layers, these being a front layer portion and a back layer portion, and which was a woven fabric in which there were weft yarns (polyester) and warp yarns (polyester/rayon). To reduce shedding of cut pile, the ground yarn portion of the base fabric was impregnated with an acrylic emulsion from the back side thereof. The extent to which causing fibers employed in pile to be hollow and porous imparted grease retention characteristics and grease deliverability thereto was determined by comparing G-type woven pile fabric to C-type woven pile fabric.

[0057] The pile fibers at the T-type woven pile fabric were crimped pile comprising multifilament employing filament of modified cross-section such that the outside circumference was split after the fashion of a “*”-like shape. The density thereof was the largest among the woven pile fabrics and knit pile fabric that were selected. While complicated and costly due to the fact that the fibers thereof were split, because the surface area thereof was greater than would have been the case had hollow and porous fibers been employed, grease retention characteristics and deliverability thereof were good.

[0058] Note that length of the pile at the foregoing respective types of pile used for testing was 3.3 mm.

[0059] The pile at the B-type knit pile fabric employed crimped pile that employed ordinary fibers. Knit properties being such as to not permit increase in pile length, thickness of the pile was less than was the case elsewhere, i.e., at the P-type, C-type, G-type, and T-type woven pile fabric, length of the pile at the pile used during testing being 2.3 mm.

Felt

[0060] In evaluating grease retention characteristics and seal characteristics of woven pile fabric and knit pile fabric in a wet end portion seal member for a linear motion mechanism, to permit comparison with pile subject to evaluation, felt (polyester felt; thickness 3 mm; density 0.2 g/cm.sup.2; 0° to 120° C. operating temperature limit) of thickness close to that of the pile subject to evaluation was employed.

Grease

[0061] During evaluation of the respective types of pile and felt, lithium greases (Grade No. 1 through No. 3) were respectively employed. Furthermore, to evaluate C-type pile, a grease of Grade No. 2 in which a molybdenum compound was blended (Mo-type), a urea-type grease of Grade No. 2 (urea-type), and a fluorinated oil used for comparative purposes were additionally employed.

Method for Evaluating Grease Retention Characteristics

[0062] The following evaluation method was used to evaluate the grease retention characteristics of the foregoing respective woven pile fabrics and knit pile fabric. Samples for evaluation were prepared in accordance with the following procedure.

[0063] Two pieces that were each 1 cm square were cut from each of the selected piles subject to evaluation. Double-sided adhesive tape was used to respectively cause the two pieces that were cut from the piles subject to evaluation to be affixed to a metal plate serving as measurement terminal that was 30 mm square×200 mm in such fashion as to maintain the spacing therebetween such that there was a distance of 150 mm between respective pile centers, and the weights while still dry (dry weight) before application of grease were measured. A grease gun was used to apply the foregoing greases to the piles subject to evaluation that had been affixed thereto until the maximum impregnable amount was reached, and the weights thereof (weight following application of grease) were measured. Note that the maximum impregnable amount was determined by visual inspection. The weight following application of grease minus the dry weight was recorded as the amount of grease that had been applied thereto.

[0064] An evaluation apparatus at which a disk that was made of aluminum and that had a diameter of on the order of 200 mm was mounted on a turntable capable being made to rotate at any desired rotational speed in such fashion that the center thereof was aligned with the center of the turntable was prepared. The metal plate serving as measurement terminal to which the two pieces of pile subject to evaluation to which the foregoing grease had been applied were affixed was placed face down in such fashion that the midpoint between said two pieces of pile subject to evaluation was aligned with the center of rotation of the disk that was made of aluminum and that had a diameter of on the order of 200 mm and was made to come in contact therewith in such fashion as to cause the pile of the pile subject to evaluation to contact the disk that was made of aluminum and that had a diameter of on the order of 200 mm. The turntable of the evaluation apparatus was made to rotate for 5 minutes at a sliding speed of 500 mm/sec while a load having a total value of 30 N was applied to the two measurement terminals to which the piles subject to evaluation had been affixed from a location above the metal plate serving as measurement terminal.

[0065] After causing rotation to stop, the metal plate serving as measurement terminal to which the two pieces of pile subject to evaluation to which grease had been applied were affixed was removed therefrom and the weight thereof (weight following sliding) was measured. The weight following application of grease minus the weight following sliding was recorded as the amount of grease that had been applied thereto but that had migrated therefrom.

[0066] Evaluation was additionally carried out in similar fashion as above except for the fact that felt was employed instead of the pile subject to evaluation and the grease employed was lithium stearate grease (Grade No. 2).

Results

[0067] Results of evaluation are shown in TABLE 2-1 and TABLE 2-2, below.

TABLE-US-00002 TABLE 2-1 Pile type P-type: straight-fiber-type C-type: crimped-type Grade No. No. 1 No. 2 No. 3 No. 1 No. 2 No. 3 Urea-type: Mo-type: Fluorinated No. 2 No. 2 oil Fiber 378,000/inch.sup.2 316,050/inch.sup.2 density Maximum 70 80 340 impregnable amount Amount of 26.0 34.1 34.5 25.9 30.0 26.2 25.3 23.2 20.7 21.2 17.7 16.2 20.9 21.0 22.1 25.5 224.2 202.7 grease that 34.9 335 48.1 31.1 31.2 31.7 15.5 15.5 22.5 23.5 23.6 23.6 22.3 22.2 19.8 20.1 215.8 230.2 migrated 34.0 34.7 38.2 33.6 31.4 34.5 17.5 15.1 20.5 20.3 25.4 25.3 14.1 16.8 21.1 20.4 200.8 205.6 therefrom 32.7 30.8 33.6 22.4 27.5 34.1 22.1 22.7 12.5 11.7 18.7 17.0 20.6 18.5 17.8 18.5 221.1 230.9 29.6 35.8 23.4 22.8 32.7 35.3 8.8 10.1 18.4 24.4 22.2 26.0 21.4 20.8 19.9 16.5 214.1 219.5 Average 32.6 31.4 31.5 17.6 19.6 21.6 19.9 20.2 216.5

TABLE-US-00003 TABLE 2-2 Pile type G-type: crimped-type T-type: crimped-type Fiber density 276,675/inch.sup.2 646,400/inch.sup.2 Grade No. No. 1 No. 2 No. 3 No. 1 No. 2 No. 3 Maximum 80 100 impregnable amount Amount of 22.8 12.5 16.6 13.2 26.0 23.1 18.6 17.6 15.8 19.4 15.0 20.3 grease that 14.6 12.9 19.8 28.9 30.0 26.3 8.2 17.2 25.7 24.5 23.7 16.3 migrated 23.8 25.5 29.3 13.6 26.8 30.1 22.4 15.1 19.4 23.2 28.9 24.6 therefrom 17.5 22.0 18.9 17.3 23.1 32.3 23.1 13.3 24.6 22.0 21.8 25.7 24.2 17.7 30.5 30.7 28.5 24.7 17.2 20.2 24.1 18.3 15.7 23.0 Average 19.4 21.9 27.1 17.3 21.7 21.5 Pile type B-type: crimped-type Felt Fiber density 179,968/inch.sup.2, t = 2.3 0.2 g/cm.sup.3 Grade No. No. 1 No. 2 No. 3 No. 2 Maximum 60 90 impregnable amount Amount of 21.8 22.0 19.1 20.4 27.2 24.6 20.6 17.4 grease that 19.8 18.8 22.5 26.0 29.3 26.1 18.8 17.9 migrated 22.6 24.4 21.2 21.4 24.1 24.8 20.8 16.3 therefrom 19.1 16.9 22.8 21.3 20.4 22.1 19.4 18.5 20.4 22.7 20.9 21.1 25.2 26.7 17.2 17.9 Average 20.9 21.7 25.1 18.5

[0068] Based on the results presented in these tables, the following was learned with respect to grease retention characteristics and grease delivery characteristics.

[0069] The maximum impregnable amount of grease varied depending on the properties possessed by the pile that was used. In addition, in spite of their low densities and high surface areas, the crimped piles had larger maximum impregnable grease amounts and permitted larger amounts of grease to be retained within the pile. It can be understood that the crimped-type piles had better grease retention characteristics than the straight-fiber-type pile.

[0070] Furthermore, among the crimped fibers, the maximum impregnable amount of grease varied in accordance with the different densities thereof. In addition, among the crimped fibers, an increase in pile density resulted in an increase in surface area and an increase in the maximum impregnable grease amount thereof, permitting a larger amount of grease to be retained within the pile. It can be understood that when crimped fiber is used, piles of higher densities will have better grease retention characteristics than piles of lower densities.

[0071] With respect to the amount of grease that migrated therefrom, this also varied depending on the properties possessed by the pile that was used. In addition, it is clear that the amount of grease which migrated from the piles that employed crimped fiber was greater than that which migrated from the pile that employed straight fiber. It can be understood that a larger amount of grease migrates in a shorter amount of time from straight-fiber-type pile—causing an excessive amount of grease to be delivered and decreasing the amount of time during which delivery of grease is possible—than from crimped-type pile.

[0072] In addition, as the P-type pile which had straight fiber had low surface area and was unable to retain grease, the amount of grease that migrated therefrom was the greatest. On the other hand, at the crimped-type C-type and G-type piles, where all or a portion of the fibers employed hollow porous fibers, it is thought that the fact that this caused these to be more crimped than they otherwise would have been was responsible for the increase in surface area and increase in the amount of grease retained thereby. In addition, based on the results obtained with the crimped-type C-type pile, it was found not only with the lithium-type grease but also with the urea-type grease and the molybdenum-type grease as well that equivalent characteristics were indicated with respect to grease retention characteristics and grease delivery characteristics. On the other hand, with the crimped-type B-type pile, despite the fact that pile thickness was small, the maximum impregnable amount of grease was small, and density was low, there was no tendency toward occurrence of a dramatic increase in the amount of grease that migrated therefrom as compared with the other crimped-type piles.

[0073] Based on the foregoing, it is clear that by using hollow porous fiber in pile employed at a wet end portion seal member for a linear motion mechanism and by increasing surface area, it will be possible to increase the amount of grease that is retained by the pile, reduce the tendency for the grease retained thereby to migrate therefrom, and inhibit excessive delivery of grease while also permitting achievement of a longer time during which delivery of grease is possible.

[0074] During use in a production setting, it being difficult during use to supply grease to the pile in a wet end portion seal member for a linear motion mechanism, because they will permit continuous use for longer times, use of C-type or T-type pile, for which the amounts of grease that migrate therefrom in a given period of time are small and which permit continuous delivery of grease for longer times, is preferred.

[0075] On the other hand, when fluorinated oil was used, because the viscosity thereof was much lower than that of the foregoing lithium grease, grease in which a molybdenum compound was blended, and urea-type grease, the maximum impregnable amount of oil was 340 mg, which means that it was possible to cause four or more times as much impregnation therewith, but a correspondingly large amount of fluorinated oil migrated therefrom, 60% or more of the impregnated amount migrating therefrom, as a result of which the amount of oil remaining within the pile was less than 40%. For this reason, as the amount of oil which remained within the pile was less than was the case for the foregoing lithium grease, grease in which a molybdenum compound was blended, and urea-type grease, this constitutes a problem with respect to endurance. Furthermore, these results raise concern that low-viscosity fluorinated oil might leak into the interior of the device of the linear motion mechanism and mix with other lubricants, and might decrease performance below that which is expected and cause occurrence of faulty operation.

Exemplary Test 2: Determination of Seal Performance of Wet End Portion Seal Member Units for Linear Motion Mechanisms

Materials and Methods

Evaluation Method

[0076] Seal members were attached to either end of a linear motion guide and sliding was made to occur for the designated time at the designated speed, following which seal performance was measured.

[0077] The piles employed were similar to those employed at Exemplary Test 1. Moreover, for comparative purposes, testing was carried out using felt similar to that used at Exemplary Test 1 and an existing product employing an end seal furnished with a nip which was made of elastomer material instead of said pile.

[0078] Pile of 5-mm width which was molded in the shape of the outside circumference of a linear guide was affixed to a plate that was attached to the end of the linear motion guide, grease in the form of lithium stearate grease (Grade No. 2) being applied thereto in an amount sufficient to cause the amount of grease on the pile to be 4 mg/cm.sup.2 to fabricate a seal member serving as sample for evaluation. For the C-type pile, a sample was additionally fabricated at which the fluorinated oil used at Exemplary Test 1 was applied thereto instead of the lithium stearate grease (Grade No. 2).

[0079] In addition, the seal members fabricated for either end of the linear motion guide were arranged in such fashion as to cause the width of the gap between the rail and the pile support frame body to be 2.0 mm, and the pile was made to bend as it was placed in an abutting relationship with respect thereto so as to occlude the region between the rail and the pile support frame body. Moreover, paper dust was sealed within a box which was placed in the region between the rail and the seal members provided at either end of said linear motion guide. For the C-type pile, a test apparatus was additionally fabricated at which, instead of paper dust, toner was sealed within a box which was placed thereat.

[0080] Then, to cause sliding to occur at the linear motion guide and investigate seal characteristics with respect to paper dust and toner at the seal members, the linear motion guide was made to engage in sliding under conditions such that the linear motion guide was driven in idler fashion continuously for an evaluation time that was a maximum of 24 hours at a maximum speed of 400 mm/sec, and the degree to which leakage of paper dust or toner had occurred and the degree to which paper dust or toner had entered the pile at the foregoing seal members was determined.

[0081] The apparatus was stopped when paper dust or toner penetrated the 5-mm width pile and leaked out therefrom. If paper dust or toner did not leak out therefrom, the seal characteristics thereof were evaluated by measuring the amount of paper dust or toner that had entered the fibers of the wet pile making up the seal member. When paper dust or toner had leaked out therefrom such that the amount which entered thereinto was 5 mm or more, a notation was made to the effect that leakage of paper dust or toner had occurred to such an extent as to make usage impractical (indicated by an x in the tables).

Results

[0082] Results of evaluation are shown in TABLE 3-1 and TABLE 3-2, below.

TABLE-US-00004 TABLE 3-1 With Grease Paper dust Toner Oil P-type: straight-fiber-type C-type: crimped-type Enmeshment: Enmeshment: Enmeshment: Enmeshment: Enmeshment: Enmeshment: Enmeshment: Enmeshment: Enmeshment Encroachment 0.8 mm 0.5 mm 0.8 mm 0.5 mm 0.8 mm 0.5 mm 0.8 mm 0.5 mm Yes Gap: 1.5 mm 3.01 1.43 0.98 0.87 0.92 0.84 1.85 1.66 Gap: 2.0 mm x x 1.16 1.15 — — — — Gap: 2.3 mm x x 3.05 155 — — — — No Gap: 1.5 mm 1.92 x 1.31 1.17 1.12 1.04 2.21 2.09 Gap: 2.0 mm x x 1.74 152 — — — — Gap: 2.3 mm x x 3.96 1.81 — — — — G-type: crimped-type T-type: crimped-type B-type: crimped-type Existing Enmeshment: Enmeshment: Enmeshment: Enmeshment: Enmeshment: Enmeshment: product Felt Enmeshment Encroachment 0.8 mm 0.5 mm 0.8 mm 0.5 mm 0.8 mm 0.5 mm (end seal) Gap 2.3 Yes Gap: 1.5 mm 1.04 0.80 1.05 1.00 2.31 2.05 x x Gap: 2.0 mm 1.01 1.10 1.49 1.04 x x Only Could only Gap: 2.3 mm x 4.52 1.66 1.26 x x evaluated be inserted No Gap: 1.5 mm 133 0.86 1.42 1.21 3.22 3.11 with grease when gas Gap: 2.0 mm 1.76 1.44 1.59 141 x x because was was 2.3 mm Gap: 2.3 mm x 3.02 1.89 1.93 x x in production Leakage environment occurred Leakage of at corners paper dust occurred Note that x indicates occurrence of leakage (5.00-mm incursion)

TABLE-US-00005 TABLE 3-2 Without Grease P-type: straight-fiber-type C-type: crimped-type G-type: crimped-type Enmeshment: Enmeshment: Enmeshment: Enmeshment: Enmeshment: Enmeshment: Enmeshment Encroachment 0.8 mm 0.5 mm 0.8 mm 0.5 mm 0.8 mm 0.5 mm Yes Gap: 1.5 mm x x x x x x Gap: 2.0 mm x x x x x x Gap: 2.3 mm x x x x x x No Gap: 1.5 mm x x x x x x Gap: 2.0 mm x x x x x x Gap: 2.3 mm x x x x x x T-type: crimped-type B-type: crimped-type Enmeshment: Enmeshment: Enmeshment: Enmeshment: Enmeshment Encroachment 0.8 mm 0.5 mm 0.8 mm 0.5 mm Yes Gap: 1.5 mm x x x x Gap: 2.0 mm x x x x Gap: 2.3 mm x x x x No Gap: 1.5 mm x x x x Gap: 2.0 mm x x x x Gap: 2.3 mm x x x x Note that x indicates occurrence of leakage (5.00-mm incursion)

[0083] When grease was not applied to pile, under all conditions tested, paper dust or toner penetrated the 5-mm width pile and leaked out therefrom. On the other hand, when grease was applied to pile, because it was found that there were samples for which there was no occurrence of leakage of paper dust despite the fact that sliding had been made to occur continuously for 24 hours, it can be understood that an extremely high degree of seal performance with respect to paper dust was imparted thereto as a result of application of grease to the pile.

[0084] In addition, seal performance varied depending on the properties of the pile that was used, it being found that seal characteristics were worse, and the extent to which there was incursion into the pile was greater, for the straight-fiber-type pile than for the crimped-type piles. With straight-fiber-type pile, it is thought that the absence of crimping causes occurrence of gaps between fibers, which tends to cause leakage of paper dust to occur. To achieve seal characteristics with straight-fiber-type pile, it is possible to address this by setting the width of the gap between the guide rail of the linear motion guide and the seal member so as to be smaller than it otherwise would be. However, this has the disadvantage that it will increase sliding resistance.

[0085] It was found that seal members employing crimped-type pile were such that seal characteristics with respect to paper dust varied depending on the type of pile that was used. With G-type pile, increasing gap width to as much as 2.3 mm resulted in increased incursion by paper dust into pile and caused occurrence of paper dust leakage. It is thought that this might be a consequence of G-type pile's having worse grease retention characteristics than those of C-type or T-type pile, which could have caused occurrence of locations at which seal characteristics were imperfect, which as a result might have caused leakage of paper dust to occur. When C-type pile that had been made to retain grease was used with a gap width of 1.5 mm, similarly good seal characteristics were exhibited thereby with respect to both paper dust and toner. On the other hand, because the density of the T-type pile was high, the amount of incursion into pile by paper dust was low under all conditions tested.

[0086] Regarding enmeshment of pile, samples at which the fiber tip portions of the cut pile were bent and made to abut the rail such that there was enmeshment thereof as a result of contact with the rail so as to occlude the gap between the rail and the support frame body tended to have better seal characteristics overall, the C-type and G-type piles in particular exhibiting a large sealing effect when the pile was enmeshed. However, when width of the gap was 2.3 mm and only the pile fiber tips were enmeshed, seal characteristics were not improved, as the effect was small. Furthermore, when width of the gap was 1.5 mm to 2.0 mm such that there was substantial enmeshment, it was found that seal characteristics could be improved even where pile density was low. With B-type pile, because thickness of the pile was small for reasons related to the constitution thereof, while an adequate seal was not achieved during the present testing in which gap width was made as small as 1.5 mm, it can be understood that it should be possible to expect that adequate seal characteristics might be achieved if the gap width were to be made even smaller.

[0087] On the other hand, with the existing end seal, paper dust leaked out from the front, making sealing impossible.

[0088] Furthermore, where felt was employed, as onset of the trend toward increase in reactive-force-producing load occurred earlier than for pile, it is clear that the narrow range of usable gap widths would make adjustment during attachment difficult, and that even if successfully attached there would be a risk of later occurrence of elevated torque (FIG. 3). Furthermore, with respect to seal characteristics as well, as leakage occurred from the corners of the felt, it was clear that it was not suitable as a material for a seal member.

[0089] Based on the foregoing, it is clear from the standpoint of seal characteristics that crimped-type fibers had the better seal characteristics, could be better made to compensate for seal characteristics when enmeshed, and permitted fabrication of a cheaper seal member.

Exemplary Test 3: Determination of Sliding Resistance of Wet End Portion Seal Member Units for Linear Motion Mechanisms

Materials and Methods

Evaluation Method

[0090] Seal members were attached to either end of a linear motion guide and sliding was made to occur for the designated time at the designated speed, following which sliding resistance was measured.

[0091] Pile similar to that used at Exemplary Test 1 was used. Pile of 5-mm width which was molded in the shape of the outside circumference of a linear guide was affixed to a plate that was attached to the end of the linear motion guide, grease in the form of lithium stearate grease (Grade No. 2) being applied thereto in an amount sufficient to cause the amount of grease on the pile to be 4 mg/cm.sup.2 to fabricate a seal member serving as sample for evaluation. In addition, the seal members fabricated for either end of the linear motion guide were arranged in such fashion as to cause the width of the gap between the rail and the pile support frame body to be 2.0 mm, and the pile was made to bend as it was placed in an abutting relationship with respect thereto so as to occlude the region between the rail and the pile support frame body.

[0092] The linear motion guide was then driven continuously in idler fashion, having been set for a maximum speed of 400 mm/sec and an evaluation time of 30 minutes, following which it was stopped, and the linear motion guide was pushed with the probe of a force gauge to measure the value of the sliding resistance thereof

Results

[0093] Results of evaluation are shown in TABLE 4, below.

TABLE-US-00006 TABLE 4 P-type: straight-fiber-type C-type: crimped-type G-type: crimped-type Enmeshment: Enmeshment: Enmeshment: Enmeshment: Enmeshment: Enmeshment: Grease Enmeshment 0.8 mm 0.5 mm 0.8 mm 0.5 mm 0.8 mm 0.5 mm Yes Yes 284 275 314 335 303 326 No 254 260 298 291 281 282 No Yes 304 310 332 347 331 351 No 290 290 328 334 317 322 T-type: crimped-type B-type: crimped-type Existing Enmeshment: Enmeshment: Enmeshment: Enmeshment: product Grease Enmeshment 0.8 mm 0.5 mm 0.8 mm 0.5 mm (end seal) Yes Yes 350 371 241 240 758 No 341 341 241 237 227 (Without seal member) No Yes 371 401 248 240 Only with No 362 373 250 243 grease because predicated on use in production environment [gf]

[0094] Based on the results presented in these tables, the following was learned with respect to the sliding resistance of end portion seal members for linear motion mechanisms.

[0095] It is clear that there was an overall tendency for sliding resistance to be lower when pile was impregnated with grease to obtain a wet end portion seal member than when the pile was not impregnated with grease. Furthermore, it is clear that while causing the pile to press against the rail of the linear guide such that it became enmeshed permitted improvement in seal characteristics, it also caused sliding resistance to increase.

[0096] With the linear motion mechanism end portion seal members that employed the P-type pile which had straight fiber, due to the fact that these employed straight fiber, there was little resistance with respect to the rail of the linear guide, and the sliding resistance thereof was low.

[0097] With the linear motion mechanism end portion seals that employed crimped-type C-type and G-type piles, whereas—perhaps due to the fact that the fibers were of similar morphology—similar sliding resistances were obtained, sliding resistance of the G-type pile was slightly lower due to the difference in density.

[0098] With the crimped-type T-type pile, as this employed crimped fiber employing fiber of modified cross-section of split “*”-like shape, while seal characteristics were good due to the fact that density was high and the surface area was large because of the modified cross-section, the fact that density was high caused sliding resistance to be on the high side as compared with other filament shapes.

[0099] As the B-type pile was knit fabric and the base fabric thereof was thin, because the gap was 2.0 mm whereas pile thickness was 2.3 mm, the yarn of the pile encroached upon the rail of the linear guide only slightly. This being the case, sliding resistance was generally low.

[0100] And regarding the end seal existing product which was employed for comparative purposes, as this was predicated on use in a production setting, evaluation was conducted by carrying out similar testing but only under the “with grease” conditions, whereupon because the end seal existing product employed elastomer material, there was a large amount of resistance due to the lip, sliding resistance being higher than was the case when pile was employed.

[0101] From the foregoing, while there is a benefit to be had in terms of seal characteristics when sliding resistance is made high, based on the results of the exemplary tests that were done which employed C-type and G-type piles, the results were such as to make it understood that causing pile to press against the rail of the linear guide such that it becomes enmeshed will make it possible to achieve adequate seal characteristics even when sliding resistance is low.

Exemplary Test 4: Determination of Seal Characteristics with Respect to Curved Surfaces

[0102] From the foregoing respective results at Exemplary Test 1, it was found that a wet end portion seal member comprising cut pile in which grease has been made to be retained in advance in the spaces between the pile fibers of the cut pile is such that by causing the fiber tip portions of the cut pile at which grease has been made to be retained in advance in the spaces between the pile fibers to abut the rail and bend so as to occlude the gap between the rail and the support frame body will make it possible to achieve adequate seal characteristics in extremely effective fashion even when sliding resistance is low.

[0103] While it so happens that there are many linear motion mechanisms constituted such that the gap to be filled therein is a flat surface, to also investigate whether it might be possible to similarly achieve adequate seal characteristics in extremely effective fashion even when sliding resistance is low even where the gap(s) to be filled include curved surface(s), as an example of a situation in which a gap to be filled includes a curved surface, a ball screw constituted such that the shape of the gap therein was a more complex curved surface was used to carry out testing to determine whether a device in accordance with the present invention might make it possible, by causing fiber tip portions of cut pile at which grease has been made to be retained in advance in spaces between pile fibers to bend in conforming fashion with respect to the ball screw so as to occlude the gap therein, to achieve adequate seal characteristics in similar fashion as was the case when a linear motion mechanism constituted such that the gap to be filled therein was a flat surface was employed.

Materials and Methods

Evaluation Method

[0104] A seal member was attached to the end of a ball screw and sliding was made to occur for the designated time at the designated speed, following which seal performance in terms of seal characteristics was evaluated based on the amount and distribution of toner that remained on the surface of the groove of the rail of the ball screw.

[0105] A ball screw in which a nut and a male-threaded shaft provided with an arcuate continuous groove threadedly engage by way of a multiplicity of steel spheres inserted between male threads and female threads, the nut being capable of being made to travel forward and backward along the male-threaded shaft; an end portion seal member at which helically arrayed at the inside circumference of a support frame body is C-type pile arranged in helical fashion at the inside circumference of the support frame body in such fashion as to oppose the groove for a length corresponding to not less than one rotation of the outside circumference of the male-threaded shaft and which is attached toward the front or toward the back from the nut of said ball screw; and C-type pile for causing helical arrayal thereof at the inside circumference of said support frame body in such fashion as to oppose the groove for a length corresponding to not less than one rotation of the outside circumference of the threaded shaft at a pitch equal to that of the groove of the ball screw were prepared.

[0106] The C-type pile was installed at the inside circumference of said support frame body in such fashion as to oppose the groove for a length corresponding to not less than one rotation of the outside circumference of the threaded shaft. In addition, grease in the form of lithium stearate grease (Grade No. 2) was applied to the C-type pile in an amount sufficient to cause the amount of grease on the pile to be 4 mg/cm.sup.2, a plate was further secured in snap-fit fashion to the insertion end face so as to prevent the pile from coming free therefrom to obtain an end portion seal member serving as sample for evaluation, following which this was attached toward the front or toward the back from the ball screw nut.

[0107] Toner (particle diameter: 5 μm) was then sprinkled on the groove of the ball screw, following which the ball screw was made to slide by hand so as cause it to cause actuation thereof for 10 reciprocating cycles, following which it was stopped, and the amount and distribution of toner that remained on the surface of the groove of the rail of the ball screw was determined.

[0108] Testing was additionally carried out using a similar procedure except for the fact that a ball screw brush seal existing product that had been molded into an annular shape was employed for comparative purposes instead of the foregoing end portion seal member that served as sample for evaluation, and the amount and distribution of toner that remained on the surface of the groove of the rail of the ball screw was determined.

Results

[0109] As a result of evaluation, it was surprisingly determined that the results which were obtained were such as to suggest that use of an end portion seal member employing wet pile in accordance with the present invention makes it possible even in situations in which the surface(s) to be sealed are made up of more or less curved surface(s) such as is the case with the groove of a ball screw to achieve adequate seal characteristics at the groove constituting the troughs of the ball screw without any fine dust from toner remaining at any of the various locations therein such that there is no occurrence of entry of toner into the bearings constituting rolling bodies therein.

[0110] In addition, it was determined that the device of the present invention made it possible for fiber tip portions of pile to make contact in such fashion as to bend and occlude gap(s) at the ball screw, and particularly gap(s) at the troughs of the ball screw, and also to be helically arrayed so as to abut the bearings constituting rolling bodies therein, as a result of which entry of fine dust from toner thereinto was prevented by the lubricant that had been made to be retained in advance in the spaces between the pile fibers as the fine dust from the toner was swept by the pile and the fiber tip portions thereof to achieve a seal so effective as not to have been achievable by the conventional art. It can be understood that the fact that pile materials used in the context of the present invention conform to and uniformly abut the ball screw and also the fact that without occurrence of leakage from abutting surfaces it is moreover the case that employment of lubricant that has been made to be retained in advance in spaces between pile fibers make it possible to obtain sealing effect and sweeping effect with respect to toner and/or other such fine dust in the context of ball screws of various configurations.

[0111] In contradistinction with respect thereto, with the existing brush seal which was a conventional product, it was determined that bands of fine dust from toner remained at various locations within the ball screw, it being the case in particular that bands of fine dust from toner remained at the troughs that were pressed on by the bearings constituting rolling bodies therein, and moreover that the situation was such that clumps of toner remained here and there therewithin. It was found with the existing brush seal which was a conventional product that the seal characteristics could not be achieved at the ball screw troughs, and that there was occurrence of toner at the bearings constituting rolling bodies therein.

[0112] It is thought that because the existing brush seal was a brush that had been molded into an annular shape, this may have caused occurrence of locations that were not touched by the brush due to the fact that the brush may not have uniformly abutted the ball screw. Close inspection was therefore carried out with respect to what abutment might exist between the existing brush seal and the ball screw, whereupon it was determined that due to the difference in height between ball screw troughs and peaks there were locations at troughs that were completely untouched despite the bending of the brush. When the surface(s) to be sealed are made up of more or less curved surface(s) such as is the case with the groove of a ball screw, it is clear that it would be difficult with an existing brush seal to seal said surfaces against intrusion by contaminants.

EXPLANATION OF REFERENCE NUMERALS

[0113] 1 Support frame body arranged at outside circumference of male-threaded shaft in split ball screw [0114] 2 Wet sealing member which contains grease and which is arranged in helically opposed fashion with respect to the groove of a ball screw [0115] 3 Plate secured to support frame body arranged at outside circumference of male-threaded shaft of ball screw to prevent wet sealing member which contains grease and which is arranged in helically opposed fashion with respect to the groove of the ball screw from coming free therefrom [0116] 4 Support frame body arranged at outside circumference of male-threaded shaft in ball screw [0117] 5 Wet sealing member which contains grease and in which pile has been cut in stripe-like fashion so as to helically conform to the groove of a ball screw so as to permit it to be arranged in helically opposed fashion with respect to the groove of the ball screw [0118] 6 Linear motion guide [0119] 7 Rail [0120] 8 Slider [0121] 9 End portion seal [0122] 10 Cut pile [0123] 11 Support frame body [0124] 12 Base fabric portion [0125] 13 Screw [0126] 14 Exterior casing