CLAMPING UNIT OF AN INJECTION MOLDING MACHINE HAVING COLUMNS

Abstract

A clamping unit of an injection molding machine having platens and columns includes a clamping-type locking apparatus by which a column is securable in relation to one of the platens at any position along a travel path of the platens relative to one another. The clamping-type locking apparatus includes a clamping jacket and a clamping device for clamping-type locking of the column in relation to the clamping jacket. The clamping device is displaceable together with the column along the travel path within the clamping jacket, when the clamping device assumes a released state, and the clamping device is configured to effect a clamping action by generating between the clamping jacket and the clamping device a locking force which is directed radially outwards in relation to a longitudinal axis of the column.

Claims

1.-10. (canceled)

11. A clamping unit of an injection molding machine having platens and columns, said clamping unit comprising a clamping-type locking apparatus by which a column is securable in relation to one of the platens at any position along a travel path of the platens relative to one another, said clamping-type locking apparatus including a clamping jacket and a clamping device for clamping-type locking of the column in relation to the clamping jacket, said clamping device being displaceable together with the column along the travel path within the clamping jacket, when the clamping device assumes a released state, said clamping device being configured to effect a clamping action by generating between the clamping jacket and the clamping device a locking force which is directed radially outwards in relation to a longitudinal axis of the column.

12. The clamping unit of claim 11, constructed for a two-platen injection molding machine.

13. The clamping unit of claim 11, wherein the clamping jacket is configured as tubular body which is grease-tight and/or dirt-tight and/or free of a release agent.

14. The clamping unit of claim 11, wherein the clamping jacket is fixed locally with respect to one of the platens.

15. The clamping unit of claim 11, wherein the clamping jacket is connected to the one of the platens, and further comprising a pressure element disposed between the pressure element and the clamping jacket.

16. The clamping unit of claim 15, wherein the pressure element is a pressure cylinder or a pressure pad.

17. The clamping unit of claim 11, wherein the clamping jacket has an interior space filled with air or oil.

18. The clamping unit of claim 11, wherein the clamping device has a pressure chamber configured for hydraulic supply with fluid to thereby pressurize the pressure chamber such as to expand radially elastically and thereby generate the locking force.

19. The clamping unit of claim 11, wherein the clamping device comprises a hydraulically actuatable wedge-type clamping apparatus which includes a clamping sleeve and an actuating sleeve, said actuating sleeve being arranged for hydraulic displacement in an axial direction within a housing of the clamping device and interacting with the clamping sleeve via a wedge or conical surface.

20. The clamping unit of claim 19, wherein the clamping device includes an open clamping chamber which points radially inwards towards the column for accommodating the actuating sleeve, said housing of the clamping device being expandable radially elastically by reaction forces applied by the wedge-type clamping device as the actuating sleeve moves relative to the clamping sleeve.

21. The clamping unit of claim 19, wherein the clamping device has an open clamping chamber which points radially outwards towards the clamping jacket for arrangement of the clamping sleeve to interact with an inner side of the clamping jacket by friction fit.

22. The clamping unit of claim 11, further comprising a stripping device provided in a region before a section of the column enters into an interior space of the clamping jacket for allowing stripping of grease and/or dirt and/or release agent from the column.

Description

[0026] In the following, the invention is explained in more detail by way of example with reference to the drawing. It is shown in:

[0027] FIG. 1: a schematic side view of a clamping unit of an injection molding machine in accordance with the invention, comprising a first embodiment of a clamping-type locking apparatus according to the invention;

[0028] FIG. 2: a schematic side view of a clamping unit of an injection molding machine in accordance with the invention, comprising a second embodiment of a clamping-type locking apparatus according to the invention;

[0029] FIG. 3: a schematic longitudinal section of a first embodiment of a clamping device of the clamping-type locking apparatus;

[0030] FIG. 4: in the upper sectional representation a second embodiment and in the lower sectional representation a third embodiment of the clamping device of a clamping-type locking apparatus, both utilizing the wedge-type clamping principle.

[0031] FIG. 1 shows a clamping unit 25 of an injection molding machine 1 in accordance with the invention with a clamping-type locking apparatus 2 according to the invention. The injection molding machine 1 has columns 3, with a clamping-type locking apparatus 2 being associated to each of the columns. The injection molding machine 1 includes a first platen 4 and a second platen 5, with a first half-mold 6 being arranged on the first platen 4 and a second half-mold 7 being arranged on the second platen 5. In the exemplary embodiment according to FIG. 1, the first platen 4 is the moving platen. The second platen 5 is the fixed platen. The moving first platen 4 is movably mounted relative to a machine bed 8 in an opening and closing direction 9 by means of displacement cylinders 10. The embodiment of the injection molding machine 1 shown in FIG. 1 is, of course, not limited to displacement cylinders 10 for opening and closing the platens 4, 5. Rather, other drives, like e.g. toggle lever drives or other linear drives for opening and closing the platens 4, 5 are appropriate as well.

[0032] Each of the columns 3 has a column longitudinal axis 3a. A clamping device 12 is located at a first end 11 of the columns 3 and is movably mounted in an associated clamping jacket 13 in the released state along the opening and closing direction 9. Pressure cylinders 15 are preferably arranged on a second end 14 of the columns and may be configured in particular as pressure pads 16. The pressure cylinders 15, in particular the pressure pads 16, are intended in a known manner to buildup the clamping force, when the platens 4, 5 have moved towards each other by means of the displacement cylinders 10 so that the half-molds 6,7 abut one another.

[0033] The clamping device 12 is capable to generate in relation to the column longitudinal axis 3a radially outwardly directed locking forces F.sub.k, which are supported on an inner side 17 of the clamping jacket 13. The clamping jacket 13 is preferably configured as a tubular body 18 which, e.g. has a circular or, optionally, also a square or rectangular cross-section. The clamping jacket 13 is secured with a first end 19 to the second platen 5. At a second end 20, the clamping jacket 13 is closed and has an end wall 21. With regard to the longitudinal extent between the first end 19 and the second end 20 or the end wall 21, the clamping jacket 13 is configured such as to be capable to surround the clamping device 12 and the column 3 along the entire travel path along the opening and closing direction 9.

[0034] In the clamping-type locking apparatus 2 according to the invention, the clamping device 12 is firmly connected to the associated column 3 and, in the released state of the clamping device 12, is shiftable within the clamping jacket 13 together with the first end 11 of the column along the entire travel path in the opening and closing direction 9.

[0035] Thus, an encapsulated clamping-type locking apparatus 2 is provided, which remains free of dirt during operation of the injection molding machine 1. The encapsulation ensures that the inner side 17 of the clamping jacket 13 and a radially outer peripheral surface 22 of the clamping device 12 are able to effect a reliable clamping or blockage of the column 3 in relation to the clamping jacket 13 at any application of the locking force F.sub.k, because the interacting surfaces (peripheral surface 22; inner side 17) remain effectively spared from contamination.

[0036] In order to prevent dirt to migrate into an interior space 23 of the clamping jacket 13 via the column 3 during travel of the platens 4, 5 along the opening and closing direction 9, stripping devices 24 are suitably provided, which are arranged, e.g., within a through-opening of the second platen 5 for passage of the column 3. The stripping devices 24 cooperate hereby with an outer side of the columns 3 and clean them before the column can reach the interior space 23 of the clamping jacket 13.

[0037] The clamping-type locking apparatus 2 according to the invention is thus formed at least by the clamping jacket 13, the clamping device 12, and a respectively associated column 3. One or more clamping-type locking apparatuses 2 according to the invention form together with one or more pressure cylinders 15 or pressure pads 16 a clamping unit 25, which ensures a reliable locking of the platens 4, 5 on one hand, and application of sufficiently high clamping forces via the pressure cylinders 15 or the pressure pads 16 on the other hand.

[0038] FIG. 2 shows a clamping unit 25 according to the invention of an injection molding machine 1, comprising at least a clamping-type locking apparatus 2 according to the invention, with the clamping-type locking apparatus 2 being coupled via pressure cylinders 15 or pressure pads 16 to the second platen 5.

[0039] In this embodiment of a clamping unit 25 of an injection molding machine 1, a plurality of identical or only slightly modified components are present compared to the embodiment according to FIG. 1, so that same reference signs are used in the following for same parts and the description will center on the differences to the embodiment according to FIG. 1. Moreover, features which are described in connection with an embodiment of the injection molding machine 1 according to FIG. 1 can be easily transferred to an injection molding machine 1 according to FIG. 2.

[0040] In contrast to the embodiment according to FIG. 1, the second end of the columns 3 is firmly secured, i.e. without interposition of a pressure pad 16 or a pressure cylinder 15, to the first platen 4. The second end of the clamping jacket 13 is accommodated inside the pressure cylinder 15 or pressure pad 16 and acts as a hydraulic piston of the pressure cylinder 15 or of the pressure pad 16. As the clamping force builds up, much smaller travel paths of the clamping jacket 13 within the pressure cylinder 15 or the pressure pad 16 are established primarily because of elastic deformation in comparison to the travel path in the opening and closing direction 9. In this embodiment, the clamping jacket 13 is movably mounted in relation to the second platen 5 within these elastically caused small travel paths. When a locking force F.sub.k is applied by the clamping device 12, each column 3 is fixed within the associated clamping jacket 13. By applying hydraulic pressure within the pressure cylinder 15 or the pressure pad 16, the clamping force can build up for clamping the molding tool (first half-mold 6 and second half-mold 7) as a result of slight displacement of the clamping jacket 13 relative to the second platen 5, caused in particular by elastic deformation of the overall arrangement.

[0041] Like in the embodiment according to FIG. 1, the stripping devices 24 can suitably be placed in a through-opening of the columns 3 of the second platen 5. As an alternative or in addition, these stripping devices 24 may also be placed in a through-opening of a bottom wall 26 of the clamping jacket 13 for passage of the column 3 in this embodiment.

[0042] The bottom wall 26 can, for example, serve as a hydraulic piston of the pressure cylinder 15 or of the pressure pad 16 and configured accordingly.

[0043] The advantages described in connection with FIG. 1 with respect to the encapsulation and the reduced or prevented contamination of the interior space 23 equally apply to the embodiment according to FIG. 2. In addition, the embodiment according to FIG. 2 offers a very compact structure, since the clamping-type locking apparatus 2 together with the pressure cylinders 15 or the pressure pads 16 can be constructed as a preassembled unit, so that the entire clamping unit 25 is compact and permits a modular preassembly.

[0044] The interior space 23 of the clamping-type locking apparatus 2 according to the invention can be filled with air or oil. It has been found that also an oil filling is suitable for high reproducibility and for sufficiently high clamping forces F.sub.k. Within the scope of the invention, it has been recognized that it is particularly important to keep moisture, dust, dirt and, in particular, grease away from the interacting surfaces for the locking force buildup of the clamping force F.sub.k. The interacting surfaces involve hereby in particular the inner side 17 of the clamping jacket 13 and the peripheral surface 22 of the clamping device 12.

[0045] A first embodiment of the clamping device 12 of the clamping-type locking apparatus 2 according to the invention is shown schematically by way of a longitudinal section in FIG. 3.

[0046] The column 3 with its column longitudinal axis 3a extends through a platen 4, 5. The stripping device 24 is situated in the platen 4, 5. The clamping jacket 13 is firmly arranged on the platen 4, 5, so that the embodiment according to FIG. 3 corresponds to the arrangement according to FIG. 1 with respect to an injection molding machine 1. The clamping-type locking apparatus 2 according to FIG. 3 is, of course, also applicable to an injection molding machine 1 according to FIG. 2.

[0047] Furthermore, for all embodiments, the clamping-type locking apparatus 2 according to the invention can selectively be arranged on a fixed or a moving platen 4, 5.

[0048] At the first end 11 of the column 3, the clamping device 12 is firmly attached, for example, by means of a screw connection. The clamping device 12 has a substantially cup-shaped three-dimensional shape and is placed on the end of the first end 11 of the column 3 and is displaceable in the opening and closing direction 9 within the clamping jacket 13, when the clamping device 12 assumes the released state (solid lines of FIG. 3). The clamping device 12 has sliding devices, for example sliding rings 27, on its peripheral surface 22 for slidingly guiding the clamping device 12 on the inner side 17 of the clamping jacket 13 in the released state. The clamping device 12 has a cup-shaped wall 28, which is arranged in the region of the first end 11 between the column 3 and the clamping jacket 13. Furthermore, the clamping device 12 has a cup-shaped bottom 29 which rests with its inner side against a free end face of the column 3. The cup-shaped bottom 29 has at least one oil channel 30 which can be filled with pressure oil, e.g. hydraulic oil. The oil channel 30 communicates with pressure chambers 31, which are provided inside the cup-shaped wall 28. Viewed across the circumference of the cup-shaped wall 28, several pressure chambers 31 can be provided or a single circumferential pressure chamber, which is slot-shaped in cross-section, can be supplied with pressure oil, or in general with a pressure medium.

[0049] A residual wall 32 thus remains between the pressure chamber 31 and the peripheral surface 22 and has a wall thickness which is reduced compared to the cup-shaped wall 28. This residual wall 32 is elastically deformable radially outwards, when pressure fluid under excess pressure is present in the pressure chamber 31 (dashed line 33 in FIG. 3). As a result of the radial expansion of the residual wall 32, the peripheral surface 22 of the clamping device 12 comes into contact with the inner side 17 of the clamping jacket 13, so that the radially outwardly acting locking force F.sub.k is generated. The level of the locking force F.sub.k depends on the pressure of the pressure fluid in the pressure chambers 31 or the pressure chamber 31. By selecting a suitably high excess pressure in the pressure chamber 31, the column 3 can thus be clamped by means of the clamping device 12 with respect to the clamping jacket 13. To release the clamping action, i.e., to reduce the locking force F.sub.k, it is only necessary to decrease the excess pressure in the pressure chamber 31, for example by opening a suitably arranged hydraulic valve (not shown). After the excess pressure in the pressure chamber 31 drops, the residual wall 32 reverts back elastically to its shape, so that the clamping device 12 is again supported to freely move along the opening and closing direction 9, as the sliding rings 27 rest upon the clamping jacket 13.

[0050] As already described above, the interior space 23 of the clamping jacket 13 can preferably be filled with air or oil. Particularly in the case of an oil filling, it is, of course, necessary to ensure suitable overflow openings or overflow passages so as to ensure a movement of the clamping device 12 within the clamping jacket 13 as unimpeded as possible. The embodiment of the clamping-type locking apparatus 2 according to FIG. 3 can be refinedas described aboveby means of pressure cylinders 15 or pressure pads 16 to form a clamping unit 25. It is, of course, also possible, to employ other drives, for example lever drives, to provide the rapid travel of the platen 4, 5 relative to one another or the application of the clamping force. In such a case, the clamping-type locking apparatus 2 according to the invention and the corresponding devices for buildup of the clamping force form hereby the clamping unit 25.

[0051] A second embodiment of the clamping-type locking apparatus 2 according to the invention is shown in the upper sectional view above the column longitudinal axis 3a according to FIG. 4.

[0052] A third embodiment of the clamping-type locking apparatus 2 according to the invention is shown schematically in FIG. 4 in the lower sectional view, below the column longitudinal axis 3a.

[0053] Both embodiments of the clamping-type locking apparatus 2 according to the invention, as shown in FIG. 4, are constructed as wedge-type clamping apparatuses 40 with a clamping sleeve 41 and an actuating sleeve 42. The actuating sleeve 42 is arranged for hydraulic displacement in an axial direction 43 within a clamping chamber 44, which is formed in the cup-shaped wall 28 of the clamping device 12. In the embodiment according to FIG. 4, the clamping chamber 44 is open above the column longitudinal axis 3a toward the column 3, with the column 3 surrounding the clamping sleeve 41. The clamping sleeve 41 and the actuating sleeve 42 interact via a wedge or conical surface 45.

[0054] Via pressure oil lines 50, 51, which communicate with pressure oil chambers 52, 53, the actuation sleeve 42 can be slightly moved along the axial direction 43 toward the clamping sleeve 41 or away from the clamping sleeve 41 by appropriately acting upon the pressure oil chambers 52. When the actuating sleeve 42 is moved toward the clamping sleeve 41, a radially outwardly acting locking force F.sub.k is generated, while the actuating sleeve 42 is supported on the cup-shaped wall 28 and the actuating sleeve 42 is supported on the wedge or conical surface 45, so that the cup-shaped wall 28 is elastically expanded and contacts with its circumferential surface 22 the inner side 17 of the clamping jacket 13, thereby building up the radially outwardly acting locking force F.sub.k. To release the clamping action, the pressure oil chambers 52, 53 are pressurized with pressure oil or subjected to a pressure reduction, such that the actuating sleeve 42 is slightly moved away from the clamping sleeve 41 in axial direction 43. Thus, the cup-shaped wall 28 can slightly spring back radially inwards so as to release the clamping action.

[0055] The second embodiment of the clamping device 12 according to the invention as shown in FIG. 4 below the column longitudinal axis 3a uses the same operating principle of the wedge-type clamping apparatus 40, wherein the clamping chamber 44 is, however, open radially outwards towards the inner side 17 of the clamping jacket 13. The actuating sleeve 42 can also be moved slightly towards and away from the clamping sleeve 41 via pressure oil lines 50, 51 in axial direction 43 within the clamping chamber 44. For this purpose, the pressure oil chambers 52, 53 are accordingly pressurized with pressure oil or fluid under pressure. The clamping sleeve 41 rests radially on the outside upon the inner side 17 of the clamping jacket 13. In order to buildup the radially outwardly acting locking force F.sub.k, the pressure oil chamber 53 is pressurized so as to slightly move the actuating sleeve 42 in axial direction 43 towards the clamping sleeve 41, so that the clamping sleeve 41 is slightly pressed radially outwardly via the wedge or conical surface 45 to thereby increase contact with the inner side 17 of the clamping jacket 13. This results in increased friction between the clamping sleeve 41 and the clamping jacket 13, so that the locking force F.sub.k is generated. To release the clamping action, excess pressure is, for example, relieved from the clamping chamber 53, and the pressure chamber 52 is acted upon by the pressure oil, so that the actuating sleeve 42 is slightly moved away from the clamping sleeve 41 in axial direction 43. The clamping sleeve 41 thereby slightly decreases in diameter and again liberates the clamping device 12 relative to the clamping jacket 13.

[0056] The support of the clamping force F.sub.k in the embodiment according to FIG. 4 (bottom) is assumed by the cup-shaped wall 28, which preferably rests flatly upon the column 3. The actuating sleeve 42 is hereby supported on a suitable support surface of the cup-shaped wall 28.

[0057] In the embodiment according to FIG. 4 (top), the locking force buildup is established by a radial expansion of the actuating sleeve 42, which causes a radial expansion of the cup-shaped wall 28, which radial expansion, however, can be reverted elastically.

[0058] In the embodiment according to FIG. 4 (bottom), a radial expansion of the clamping sleeve 41 is established, which radial expansion can be elastically reverted when the actuating sleeve 42 is correspondingly shifted within the clamping chamber 44.

[0059] In both embodiments according to FIG. 4, the clamping sleeve 41 and the actuating sleeve 42 as well as contact surfaces of the cup-shaped wall 28, which has a clamping chamber 44, thus act as wedge-type clamping device 55. The cup-shaped wall 28 together with the cup-shaped bottom 28 form hereby a housing 56 for receiving the wedge-type clamping device 55.

REFERENCE SIGNS

[0060] 1 injection molding machine [0061] 2 clamping-type locking apparatus [0062] 3 column [0063] 3a column longitudinal axis [0064] 4 first platen [0065] 5 second platen [0066] 6 first half-mold [0067] 7 second half-mold [0068] 8 machine bed [0069] 9 opening and closing apparatus [0070] 10 displacement cylinder [0071] 11 first end of 3 [0072] 12 clamping device [0073] 13 clamping jacket [0074] 14 second end of 3 [0075] 15 pressure cylinder [0076] 16 pressure pad [0077] 17 inner side [0078] 18 tubular body [0079] 19 first end of 13 [0080] 20 second end of 13 [0081] 21 end wall [0082] 22 peripheral surface [0083] 23 interior space [0084] 24 stripping device [0085] 25 clamping unit [0086] 26 bottom wall [0087] 27 sliding rings [0088] 28 cup-shaped wall [0089] 29 cup-shaped bottom [0090] 30 oil channel [0091] 31 pressure chamber [0092] 32 residual wall [0093] 33 dashed line [0094] 40 wedge-type clamping apparatus [0095] 41 clamping sleeve [0096] 42 actuating sleeve [0097] 43 axial direction [0098] 44 clamping chamber [0099] 45 wedge or conical surface [0100] 55 wedge-type clamping device [0101] 50, 51 pressure oil lines [0102] 52, 53 pressure oil chambers [0103] 55 wedge-type clamping device [0104] 56 housing [0105] F.sub.k locking force cm What is claimed is: