Guide mechanism of machine tool and machine tool

Abstract

A guide mechanism for a machine tool includes a movement member and a guide member in a form of first and second rails the movement member and the guide member relatively movable to each other. A hydrostatic pressure guide mechanism and a sliding guide mechanism are formed between the movement member and the first and second rails. The hydrostatic pressure guide mechanism includes a static pressure chamber, a seal portion sealing a periphery of the static pressure chamber, and a supply passage configured to supply a lubricating oil into the static pressure chamber.

Claims

1. A guide mechanism for a machine tool, comprising: a first member and a second member relatively movable to each other; and a hydrostatic pressure guide mechanism and a sliding guide mechanism formed between the first and second members, wherein the hydrostatic pressure guide mechanism comprises: a smooth guide surface formed on the first member; a static pressure chamber formed on the second member to face the guide surface; a seal portion surrounding the static pressure chamber; and a supply passage configured to supply a lubricating oil into the static pressure chamber; and the sliding guide mechanism comprises: the smooth guide surface formed on the first member; a slide surface formed on the second member to face and slidingly contact the guide surface; and an oil supply groove formed on the slide surface.

2. The guide mechanism for a machine tool according to claim 1, wherein the hydrostatic pressure guide mechanism comprises a recovery passage configured to recover the lubricating oil from the static pressure chamber.

3. The guide mechanism for a machine tool according to claim 2, wherein the supply passage supplies the lubricating oil to near the periphery of the static pressure chamber, and the recovery passage recovers the lubricating oil from a center of the static pressure chamber.

4. The guide mechanism for a machine tool according to claim 1, wherein the first member is a guide member and the second member is a movement member relatively movable along the guide member, the guide member comprises a smooth guide surface, and the hydrostatic pressure guide mechanism and the sliding guide mechanism are formed between the movement member and the guide surface and use the guide surface in common.

5. The guide mechanism for a machine tool according to claim 4, wherein the movement member comprises: the static pressure chamber facing the guide surface; and the seal portion surrounding the static pressure chamber, and the static pressure chamber and the guide surface define the hydrostatic pressure guide mechanism.

6. The guide mechanism for a machine tool according to claim 4, wherein the movement member comprises: the slide surface facing the guide surface; and the oil supply groove formed on the slide surface, and the slide surface and the guide surface define the sliding guide mechanism.

7. The guide mechanism for a machine tool according to claim 1, wherein the sliding guide mechanism is provided inside the machine tool and the hydrostatic pressure guide mechanism is fixed to each end of the sliding guide mechanism.

8. A machine tool comprising the guide mechanism for a machine tool according to claim 1.

9. The machine tool according to claim 8, further comprising: a fixed member; a movement member configured to move in a horizontal direction relative to the fixed member; and a guide mechanism for supporting a load extending in the horizontal direction and a guide mechanism for tilt prevention configured to resist inclination relative to the guide mechanism for supporting the load, the guide mechanisms being provided between the fixed member and the movable member.

Description

BRIEF DESCRIPTION OF DRAWING(S)

(1) FIG. 1 is a perspective view showing an entire device according to a first exemplary embodiment of the invention.

(2) FIG. 2 is a perspective view showing a layout of a movement member according to the first exemplary embodiment.

(3) FIG. 3 is an exploded perspective view showing a movement mechanism according to the first exemplary embodiment.

(4) FIG. 4 is a perspective view showing a relevant part of a hydrostatic pressure guide mechanism and a sliding guide mechanism provided to the movement member according to the first exemplary embodiment.

(5) FIG. 5 is a cross-sectional view showing the hydrostatic pressure guide mechanism according to the first exemplary embodiment.

(6) FIG. 6 is a cross-sectional view showing the sliding guide mechanism according to the first exemplary embodiment.

(7) FIG. 7 is a perspective view showing a relevant part of a hydrostatic pressure guide mechanism and a sliding guide mechanism provided to a movement member according to a second exemplary embodiment.

(8) FIG. 8 is a cross-sectional view showing the hydrostatic pressure guide mechanism according to the second exemplary embodiment.

(9) FIG. 9 is an exploded perspective view showing a movement mechanism according to a third exemplary embodiment of the invention.

(10) FIG. 10 is a perspective view showing a relevant part of a hydrostatic pressure guide mechanism and a sliding guide mechanism provided to the movement member according to the third exemplary embodiment.

(11) FIG. 11 is a perspective view showing an entire device according to a fourth exemplary embodiment of the invention.

(12) FIG. 12 is a cross-sectional view showing a layout of a movement mechanism according to the fourth exemplary embodiment.

(13) FIG. 13 is an exploded perspective view showing a modification of the movement mechanism according to the fourth exemplary embodiment.

(14) FIG. 14 is a cross-sectional view showing another exemplary embodiment of the invention.

DESCRIPTION OF EMBODIMENT(S)

First Exemplary Embodiment

(15) FIGS. 1 to 6 show a first exemplary embodiment of the invention.

(16) As shown in FIG. 1, the machine tool 10 includes a platform 11 extending in the X-axis direction and a table 12 supported by the platform 11. A pair of columns 13 are provided on both sides of the platform 11. A cross bar 14 extends in the Y-axis direction between upper ends of the columns 113. A head 15 is supported by the cross bar 14. A ram 16 extending in the Z-axis direction (vertical direction) is attached to the head 15.

(17) A workpiece 19, which is an object to be machined, is fixed on a top surface of the table 12. A main spindle 17 is exposed from a lower end of the ram 16. A machining tool 18 is attached to the main spindle 17.

(18) In the machine tool 10, the tool 18 can be moved in three dimensions relatively to the workpiece 19 by moving the table 12 in the X-axis direction, moving the head 15 in the Y-axis direction, and moving the ram 16 in the Z-axis direction. With this relative movement, the workpiece 19 can be machined into any shapes.

(19) In order to machine the workpiece in three dimensions as described above, the machine tool 10 is provided with an X-axis movement mechanism 21 for moving the table 12 in the platform 11, a Y-axis movement mechanism 22 for moving the head 15 along the cross bar 14, and a Z-axis movement mechanism 23 for moving the ram 16 relative to the head 15.

(20) The X-axis movement mechanism 21, the Y-axis movement mechanism 22, and the Z-axis movement mechanism 23 each support a moving portion (e.g., the table 12 relative to the platform 11) in a manner to allow the moving portion to be moved, and each include a guide mechanism that guides the moving portion in a predetermined moving direction and a drive mechanism (e.g., a motor) that drives the moving portion based on an external command.

(21) In the Y-axis movement mechanism 22 for the head 15 and the cross bar 14 among the movement mechanisms 21 to 23, a plurality of guide mechanisms 30 (see, first to sixth guide mechanisms 30A to 30F, FIG. 2) extending in the Y-axis direction are employed.

(22) As shown in FIG. 2, the cross bar 14 includes: a first rail 141 provided to an upper portion of a side of the cross bar 14 to which the head 15 is attached; and a second rail 142 provided to a lower portion of the side of the cross bar 14 to which the head 15 is attached. The head 15 includes: a first groove 151 facing downward and provided to an upper portion of the head 15 near the cross bar 14; and a second groove 152 provided to a lower portion of the head 15 near the cross bar 14.

(23) The second groove 152 formed in the head 15 is engaged with the second rail 142 of the cross bar 14, thereby supporting a load in the Z-axis direction and restricting a position of the head 15 in the X-axis direction.

(24) The first groove 151 formed in the head 15 is engaged with the first rail 141 of the cross bar 14, thereby restricting the position of the head 15 in the X-axis direction and restricting the head 15 from tilting due to its own weight around the second rail 142 supporting the load.

(25) First and second movement members 31A and 31B for holding the first rail 141 therebetween in the X-axis direction are provided on an inner side of the first groove 151. Using the first rail 141 as a guide member, the first and second movement members 31A and 31B respectively provide first and second guide mechanisms 30A and 30B according to the first exemplary embodiment.

(26) On an inner side of the second groove 152, third and fourth movement members 31C and 31D are provided to hold the second rail 142 therebetween in the X-axis direction and fifth and sixth movement members 31E and 31F are provided to hold the second rail 142 therebetween in the Z-axis direction. Using the first rail 141 as a guide member, the third to sixth movement members 31C to 31F respectively provide third to sixth guide mechanisms 30C to 30F according to the first exemplary embodiment.

(27) Guide Mechanism 30

(28) As shown in FIG. 3, a guide mechanism 30 (first to sixth guide mechanisms 30A to 30F, see FIG. 2) includes: a movement member 31 (movement members 31A to 31F, see FIG. 2) and the first and second rails 141 and 142 as the guide member, the movement member and the guide member being relatively movable to each other.

(29) The movement member 31 (the first to sixth movement members 31A to 31F) is a member extending in a relative moving direction of the guide mechanism 30 and is formed with use of a plate fixed to the head 15 along the first and second grooves 151 and 152 or a part of the head 15.

(30) Thick stepped portions are formed at both ends on a side of the movement member 31 facing the first and second rails 141 and 142. A surface of each of the thick stepped portions functions as a smooth surface 49 and a slide surface 51. The movement member 31 has a pair of lateral surfaces in a direction orthogonal to a thickness direction of the movement member 31.

(31) The first and second rails 141 and 142 are members extending in a relative moving direction of the guide mechanism 30 and are formed with use of a separate member fixed along to the cross bar 14 or a part of the cross bar 14.

(32) A surface of each of the first and second rails 141 and 142 facing the movement member 31 is defined as a guide surface 39 that is smooth along the whole length.

(33) The movement member 31 and the first and second rails 141 and 142 are disposed such that the smooth surface 49 and the slide surface 51 at each end of the movement member 31 are in hermetic contact with the guide surface 39 of each of the first and second rails 141 and 142, thereby providing the guide mechanism 30.

(34) In this arrangement, a hydrostatic pressure guide mechanism 40 is formed between the smooth surface 49 and the guide surface 39 while a sliding guide mechanism 50 is formed between the slide surface 51 and the guide surface 39.

(35) A sheet formed using a low friction material (e.g., tetrafluoroethylene) is adhered continuously all over the slide surface 51 and the smooth surface 49.

(36) It should be noted that the smooth surface 49 on an outer side of the hydrostatic pressure guide mechanism 40 may be cut deeper than the slide surface 51 and be provided as a flank surface in no contact with the guide surface 39.

(37) The hydrostatic pressure guide mechanism 40 floats and supports the first and second rails 141 and 142 by static pressure against the movement member 31, using pressurized lubricating oil to be supplied from the outside, which will be described below in detail. In order to supply and recover the lubricating oil for such an intended use, a lubricating oil supply device 60 is connected to the hydrostatic pressure guide mechanism 40.

(38) As shown in FIGS. 3 and 4, the lubricating oil supply device 60 includes: a tank 61 that stores the lubricating oil; and a supply pipe 63 and a recovery pipe 64 that connect the tank 61 to the hydrostatic pressure guide mechanism 40.

(39) A filter 65 that filters the lubricating oil passing therethrough and a pump 62 that pressurizes the lubricating oil are installed in the supply pipe 63.

(40) With this arrangement, the lubricating oil supply device 60 takes out the lubricating oil stored in the tank 61 through the supply pipe 63, filters the lubricating oil using the filter 65, and subsequently pumps the filtered lubricating oil using the pump 62, so that the lubricating oil can be supplied to the hydrostatic pressure guide mechanism 40. Moreover, the recovery pipe 64 can recover the lubricating oil from the hydrostatic pressure guide mechanism 40 and return the lubricating oil to the tank 61.

(41) The lubricating oil supply device 60 also supplies the lubricating oil to be used in the sliding guide mechanism 50.

(42) As shown in FIGS. 3 and 4, the lubricating oil supply device 60 includes: a tank 69 that stores the lubricating oil; and a supply pipe 66 that connects the tank 69 to the sliding guide mechanism 50.

(43) A filter 68 that filters the lubricating oil passing therethrough and a pump 67 that intermittently pumps the lubricating oil at a suitable amount are installed in the supply pipe 66.

(44) As a discharge passage of the lubricating oil supplied to the sliding guide mechanism 50, a recovery pipe 55 that receives the lubricating oil discharged from the sliding guide mechanism 50 and a waste oil tank 56 that stores the lubricating oil collected by the recovery pipe 55 are provided below the lateral surface of the movement member 31. The discharge passage is occasionally provided by a pipe as needed.

(45) In other words, in the first exemplary embodiment, the same kind of the lubricating oil is supplied to both of the hydrostatic pressure guide mechanism 40 and the sliding guide mechanism 50 by the lubricating oil supply device 60.

(46) However, the amount of the lubricating oil to be used in the sliding guide mechanism 50 is sufficiently lower than that in the hydrostatic pressure guide mechanism 40. Moreover, the lubricating oil is intermittently supplied in the sliding guide mechanism 50. In order to handle the different supply conditions, the lubricating oil supply passage to the sliding guide mechanism 50 and the lubricating oil supply passage to the hydrostatic pressure guide mechanism 40 are provided as completely independent systems.

(47) The hydrostatic pressure guide mechanism 40 and the sliding guide mechanism 50 in the first exemplary embodiment will be described below.

(48) Hydrostatic Pressure Guide Mechanism 40

(49) As shown in FIGS. 4 and 5, in the first exemplary embodiment, the smooth surface 49 of the hydrostatic pressure guide mechanism 40 and the slide surface 51 of the sliding guide mechanism 50 define a continuously flat surface.

(50) Specifically, a static pressure chamber 41 and other elements are formed on an extension of the slide surface 51 on which the sliding guide mechanism 50 is formed, and the first and second rails 141 and 142 (i.e., guide member) face the static pressure chamber 41 to cover the static pressure chamber 41 with the guide surface 39, thereby providing the hydrostatic pressure guide mechanism 40.

(51) As shown in FIG. 4, the hydrostatic pressure guide mechanism 40 includes: the circular static pressure chamber 41 shaped as a recess on the smooth surface 49; and an annular seal portion 42 in a form of a ring continuously surrounding the static pressure chamber 41.

(52) Although the static pressure chamber 41 is depicted as a recess in FIGS. 3 and 5, the static pressure chamber 41 becomes a closed space covered with the guide surfaces 39 of the first and second rails 141 and 142 in the assembled guide mechanism 30.

(53) A communication hole 431 of a supply passage 43 communicates with a part of the seal portion 42.

(54) The above-described supply pipe 63 of the lubricating oil supply device 60 is connected to the supply passage 43. The pressurized lubricating oil is supplied into the static pressure chamber 41 through the supply pipe 63.

(55) A communicating hole 441 of a recovery passage 44 communicates with the center of static pressure chamber 41.

(56) The above-described recovery pipe 64 of the lubricating oil supply device 60 is connected to the recovery passage 44. The lubricating oil is recovered from the static pressure chamber 41 through the recovery pipe 64.

(57) As also shown in FIG. 5, the communicating hole 441 of the above-described recovery passage 44 communicates with the center of a bottom of the static pressure chamber 41. An annular groove 411 is also formed on the bottom of the static pressure chamber 41 so as to be concentric with the communicating hole 441

(58) The bottom of the static pressure chamber 41 is divided into an inner part 412 and an outer part 413 by the annular groove 411. A communication groove 414 extending in a radial direction from the annular groove 411 to the seal portion 42 is formed on a part of the outer part 413.

(59) The seal portion 42 includes an annular seal groove 421 along a periphery of the static pressure chamber 41. A seal member 422, which is provided by an elastomer molding article (e.g., oil resistant rubber), is disposed in the seal groove 421. The communication hole 431 of the supply passage 43 communicates with a part of the seal groove 421 which is an inner part relative to the seal member 422 (i.e., a part closer to the static pressure chamber 41).

(60) In the hydrostatic pressure guide mechanism 40 with this arrangement, the pressurized lubricating oil is supplied from the supply passage 43 to flow through the seal groove 421 into the static pressure chamber 41. After moving from the outer part 413 to the inner part 412 in the static pressure chamber 41, the pressurized lubricating oil is recovered to the recovery passage 44 through the communicating hole 441.

(61) In this arrangement, the lubricating oil in the static pressure chamber 41 floats and supports the guide surface 39 by the static pressure, thereby effecting the function of the hydrostatic pressure guide mechanism 40.

(62) All the amount of the lubricating oil in the static pressure chamber 41 is recovered through the recovery passage 44. Further, since the periphery of the static pressure chamber 41 is sealed with the seal portion 42, the lubricating oil is prevented from overflowing to the outside.

(63) In the first exemplary embodiment, a thickness of the static pressure chamber 41 (a distance between the inner part 412 and the guide surface 39), in other words, a depth of a recess from the smooth surface 49, is much smaller (about several ten microns) than those of the seal groove 421 and the annular groove 411.

(64) Further, the inner part 412 and outer part 413 are set in the same height. In other words, the depth of the static pressure chamber 41 at the inner part 412 (the depth from the smooth surface 49) is the same as the depth thereof at the outer part 413.

(65) Accordingly, in the assembled guide mechanism 30, the thickness of the static pressure chamber 41 at the outer part 413 (i.e., a distance between the outer part 413 and the guide surface 39) is the same as the thickness of the static pressure chamber 41 at the inner part 412 (i.e., the distance between the inner part 412 and the guide surface 39).

(66) The annular groove 411 is formed between the inner part 412 and the outer part 413 and communicates with the seal groove 421 through the communication groove 414. Accordingly, the pressure of the lubricating oil at the outer part 413 is kept the same as the pressure of the lubricating oil supplied from the supply passage 43 through the communication hole 431.

(67) By this setting, when the lubricating oil flows from the outer part 413 to the inner part 412 in the static pressure chamber 41, the inner part 412 serves as a land or a pressure holding portion.

(68) Specifically, the pressure of the lubricating oil at an outer side (i.e., a region facing the annular groove 411) of the inner part 412 is the same as that at the outer part 413, but is gradually decreased as the lubricating oil flows inward and reaches approximately atmospheric pressure when the lubricating oil reaches the communicating hole 441 of the recovery passage 44.

(69) Since the inner part 412 thus serves as the land or the pressure holding portion, the static pressure for supporting the load can be secured at the outer part 413 serving as a recess or a static pressure chamber body.

(70) Further, since supporting of the load by the lubricating oil using the static pressure in the static pressure chamber 41 is conducted at the outer part 413 provided on an outer side of the static pressure chamber 41 and having a larger area therein, an area of a region receiving the pressure can be expanded and the supporting of the load using the static pressure can be efficiently conducted by the lubricating oil having a high pressure immediately after flowing into the static pressure chamber 41.

(71) Sliding Guide Mechanism 50

(72) As shown in FIG. 4, the sliding guide mechanism 50 has the smooth slide surface 51. An oil supply groove 52 is continuously formed in a planar matrix on the slide surface 51.

(73) As shown in FIG. 6, the oil supply groove 52 communicates with the oil supply passage 53. The above-described supply pipe 66 of the lubricating oil supply device 60 is connected to the oil supply passage 53.

(74) In the sliding guide mechanism 50, the first and second rails 141 and 142 (the guide member) are supported by bringing the slide surface 51 into contact with the guide surface 39 and are relatively movable by sliding the slide surface 51 and the guide surface 39 on each other.

(75) In the sliding guide mechanism 50, the lubricating oil supplied to the oil supply passage 53 is spread over the slide surface 51 by the oil supply groove 52, whereby slide resistance and wear between the slide surface 51 and the guide surface 39 can be reduced.

(76) In the sliding guide mechanism 50 according to the first exemplary embodiment, the lubricating oil supplied between the guide surface 39 and the slide surface 51 is the same as the lubricating oil supplied to the hydrostatic pressure guide mechanism 40. Accordingly, even when the lubricating oil is leaked from the hydrostatic pressure guide mechanism 40 and is mixed with the lubricating oil in the sliding guide mechanism 50, no trouble occurs since both of the lubricating oils are the same.

(77) Moreover, since the same lubricating oil is used in the sliding guide mechanism 50 and the hydrostatic pressure guide mechanism 40, the same tank is usable in common instead of separate tanks 61 and 69.

(78) Advantages of First Exemplary Embodiment

(79) According to the first exemplary embodiment as described above, the following advantages can be obtained in addition to the respective advantages described in relation to the hydrostatic pressure guide mechanism 40 and the sliding guide mechanism 50.

(80) In the first exemplary embodiment, the hydrostatic pressure guide mechanism 40 is a hermetically-closed hydrostatic pressure guide mechanism, in which the periphery is sealed by the seal portion 42 and the lubricating oil is supplied from the supply passage 43, recovered from the recovery passage 44, and is circulated into tank 61.

(81) Accordingly, in the hydrostatic pressure guide mechanism 40, the lubricating oil can be prevented from overflowing to the outside through the periphery, or the overflowing of the lubricating oil can be restricted to the minimum level.

(82) Further, even when the hydrostatic pressure guide mechanism 40 and the sliding guide mechanism 50 are provided together, the possibility that the lubricating oil overflowing from the hydrostatic pressure guide mechanism 40 adversely affects the sliding guide mechanism 50 can be eliminated.

(83) A high load capacity and a low friction can be secured by the hydrostatic pressure guide mechanism 40 and the guiding accuracy and the damping performance can be secured by the sliding guide mechanism 50. As a result, the guide mechanism 30 having a high load capacity, a low friction, a high guiding accuracy and a high damping performance can be provided.

(84) In the first exemplary embodiment, the movement member 31, which is one of the two mutually relatively movable members described above, collectively includes a main structure (e.g., the static pressure chamber 41 and the oil supply groove 52) of the hydrostatic pressure guide mechanism 40 and the sliding guide mechanism 50. The first and second rails 141 and 142, each of which is the other of the above two members, only have the guide surface 39.

(85) In other words, since the hydrostatic pressure guide mechanism 40 and the sliding guide mechanism 50 use the guide surface 39 of each of the first and second rails 141 and 142 (i.e., the guide member) in common, the respective structures of the hydrostatic pressure guide mechanism 40 and the sliding guide mechanism 50 can be simplified as compared with a structure of each of those having the guide surface, so that an entirety of the guide mechanism 30 can be reduced in size.

(86) Moreover, since the main structures (e.g., the static pressure chamber 41 and the oil supply groove 52) of the hydrostatic pressure guide mechanism 40 and the sliding guide mechanism 50 can be collectively provided to the movement member 31, the structure of the guide mechanism 30 can be further simplified. Further, since the hydrostatic pressure guide mechanism 40 and the sliding guide mechanism 50 are juxtaposed on the surface of the movement member 31 facing the guide surface 39, the load can be reliably shared by the hydrostatic pressure guide mechanism 40 and the sliding guide mechanism 50.

Second Exemplary Embodiment

(87) FIGS. 7 to 8 show a second exemplary embodiment of the invention.

(88) In the second exemplary embodiment, the guide mechanism 30 according to the second exemplary is provided to the machine tool 10 similar to that in the first exemplary embodiment.

(89) In the second exemplary embodiment, the respective basic structures of the machine tool 10, the guide mechanism 30, the hydrostatic pressure guide mechanism 40 and the sliding guide mechanism 50 are the same. Hence, a duplicated description is omitted and a different structure(s) will be described below.

(90) In the above first exemplary embodiment, the static pressure chamber 41 of the hydrostatic pressure guide mechanism 40 includes the annular groove 411, the inner part 412, the outer part 413 and the communication groove 414. Although the inner part 412 and the outer part 413 have the same depth, since the annular groove 411 and the communication groove 414 communicate with the seal groove 421, the inner part 412 functions as the pressure holding portion (the land) and the outer part 413 serves as the static pressure chamber body (the recess).

(91) In the second exemplary embodiment, the annular groove 411 and the communication groove 414 are omitted. The depth of the outer part 413 is formed larger than that of the inner part 412. With this arrangement, the inner part 412 functions as the land (the pressure holding portion) and the outer part 413 functions as the recess (the static pressure chamber body).

(92) In the second exemplary embodiment, the depth of the inner part 412 is approximately several ten microns the same as in the first exemplary embodiment. The depth of the outer part 413 is larger than that of the inner part 412.

(93) In the above first exemplary embodiment, the lubricating oil supply device 60 includes the passage for supplying and recovering the lubricating oil to and from the hydrostatic pressure guide mechanism 40, and in addition, includes the passage for supplying the lubricating oil to the sliding guide mechanism 50.

(94) In contrast, in the second exemplary embodiment, the tank 61 is used in common. The supply pipe 63 extending to the hydrostatic pressure guide mechanism 40 and the supply pipe 66 extending to the sliding guide mechanism 50 are connected to the same tank 61.

(95) According to the second exemplary embodiment, since the respective basic structures of the machine tool 10, the guide mechanism 30, the hydrostatic pressure guide mechanism 40 and the sliding guide mechanism 50 are the same as those in the first exemplary embodiment, the same advantages can be obtained.

(96) Further, in the second exemplary embodiment, the annular groove 411 and the communication groove 414 are omitted. However, supporting of the load by the lubricating oil using the static pressure can be conducted in the same manner as in the first exemplary embodiment by setting the depth of each of the inner part 412 and the outer part 413, thereby effecting the function of the hydrostatic pressure guide mechanism 40.

(97) Further, the structure of the lubricating oil supply device 60 can be simplified by using the same tank 61 for supplying the lubricating oil to the hydrostatic pressure guide mechanism 40 and the sliding guide mechanism 50. Even in the above arrangement, no functional trouble occurs since the same lubricating oil is used in the hydrostatic pressure guide mechanism 40 and the sliding guide mechanism 50.

Third Exemplary Embodiment

(98) FIGS. 9 to 10 show a third exemplary embodiment of the invention.

(99) In the above first and second exemplary embodiments, the slide surface 51 and the smooth surface 49 are continuously formed on the surface at each end of the movement member 31. The hydrostatic pressure guide mechanism 40 is provided adjacent to the sliding guide mechanism 50.

(100) In contrast, in the third exemplary embodiment, the hydrostatic pressure guide mechanism 40 and the sliding guide mechanism 50 are respectively formed in separate members.

(101) As shown in FIGS. 9 and 10, in the third exemplary embodiment, the sliding guide mechanism 50 is formed in the movement member 31, but the hydrostatic pressure guide mechanism 40 is not formed therein.

(102) However, on each end of the movement member 31, a block-shaped auxiliary movement member 48 is provided. The hydrostatic pressure guide mechanism 40 is formed in the auxiliary movement member 48.

(103) The auxiliary movement member 48 is provided to an outer surface of the spindle head 15 (see FIG. 2) to which the movement member 31 is provided, and is firmly fixed to a frame of the spindle head 15.

(104) The smooth surface 49 of the auxiliary movement member 48 is flush with the slide surface 51 of the movement member 31.

(105) The static pressure chamber 41 and the seal portion 42 are formed on the smooth surface 49 of the auxiliary movement member 48. The supply passage 43 and the recovery passage 44 are formed inside the auxiliary movement member 48.

(106) The same hydrostatic pressure guide mechanism 40 as in the first and second exemplary embodiments is provided by the static pressure chamber 41, the seal portion 42, the supply passage 43 and the recovery passage 44.

(107) According to the third exemplary embodiment, since the sliding guide mechanism 50 formed on the movement member 31 is disposed adjacent to the hydrostatic pressure guide mechanism 40 formed on the auxiliary movement member 48 and both of the hydrostatic pressure guide mechanism 40 and the sliding guide mechanism 50 are guided relative to the guide surface 39 of the first and second rails 141 and 142 (the guide member), the same advantages as those in the first and second exemplary embodiments can be obtained.

(108) Further, in the third exemplary embodiment, the hydrostatic pressure guide mechanism 40 is formed on the auxiliary movement member 48 independent of the movement member 31. Accordingly, the guide mechanism according to the third exemplary embodiment can be easily implemented by additionally providing (so-called retrofitting) the auxiliary movement member 48 having the hydrostatic pressure guide mechanism 40 to an existing machine tool including the movement member 31 in which only the sliding guide mechanism 50 is formed. Thus, the existing machine is usable.

Fourth Exemplary Embodiment

(109) FIGS. 11 to 12 show a fourth exemplary embodiment of the invention.

(110) A shown in FIG. 11, a machine tool 10S of the fourth exemplary embodiment includes a first groove 1515 on an upper portion of the spindle head 15, in which the first groove 1515 is engaged with a first rail 141S of the cross bar 14, in the same manner as in the machine tool 10 of the first exemplary embodiment (see FIG. 1). Moreover, the machine tool 10S includes a second groove 152 on a lower portion of the spindle head 15, in which the second groove 152 is engaged with the second rail 142 of the cross bar 14.

(111) As shown in FIG. 12, a guide mechanism 30T for supporting the load (guide mechanisms 30CT, 30DT, 30ET, 30FT) is provided between the second groove 152 and the second rail 142.

(112) The guide mechanism 30T for supporting the load (guide mechanisms 30CT, 30DT, 30ET, 30FT) is arranged in the same manner as the guide mechanism 30 (guide mechanisms 30C, 30D, 30E, 30F) in the above first exemplary embodiment.

(113) In the guide mechanism 30 according to the first exemplary embodiment, the guide mechanisms 30C, 30D, 30E and 30F each include the hydrostatic pressure guide mechanism 40 and the sliding guide mechanism 50 on the corresponding movement members 31C, 31D, 31E and 31F.

(114) In contrast, in the guide mechanism 30T according to the fourth exemplary embodiment, the guide mechanisms 30CT, 30DT, 30ET and 30FT each include only the sliding guide mechanism 50 on the corresponding movement members 31CT, 31DT, 31ET and 31FT.

(115) In other words, in the fourth exemplary embodiment, the hydrostatic pressure guide mechanism 40 is not used for the guide mechanism 30T for supporting the load.

(116) The movement members 31CT, 31DT, 31ET and 31FT only including the sliding guide mechanism 50 are only required to have the same arrangement as that of the movement member 31 in the third exemplary embodiment (see FIG. 9).

(117) A guide mechanism 30S for preventing the spindle head 15 from tilting is provided between the first groove 1515 and the first rail 141S.

(118) The first rail 141S has an inclined guide surface 39S. A movement member 31S is provided inside the first groove 1515 so as to face the guide surface 39S. The guide mechanism 30S is formed by the guide surface 39S and the movement member 31S.

(119) In the fourth exemplary embodiment, the guide mechanism 30S only has the hydrostatic pressure guide mechanism 40 on the movement member 31S.

(120) A guide mechanism 30AS accompanying the guide mechanism 30S is formed between the spindle head 15 and the first rail 141S. The guide mechanism 30AS is arranged in the same manner as the guide mechanism 30A in the first exemplary embodiment, in which the guide mechanism 30AS includes a vertical guide surface 39A and a movement member 31AS slidable on the guide surface 39A.

(121) Although the guide mechanism 30A according to the first exemplary embodiment includes the hydrostatic pressure guide mechanism 40 and the sliding guide mechanism 50 on the movement member 31A, the guide mechanism 30AS according to the fourth exemplary embodiment includes only the sliding guide mechanism 50 on the movement member 31AS.

(122) With this arrangement, the weight of the spindle head 15 can be supported by the cross bar 14 using the guide mechanism 30T at the lower portion of the spindle head 15. Moreover, since the guide mechanism 30S is formed inclined on the upper portion of the spindle head 15, the guide mechanism 30S can receive tilt moment by the weight of the spindle head 15, so that the spindle head 15 can be prevented from tilting.

(123) In this arrangement, since the guide mechanism 30S for tilt prevention is provided by the hydrostatic pressure guide mechanism 40 formed between the guide surface 39S and the movement member 31S, a high load capacity can be provided. On the other hand, since the sliding guide mechanism 50 is used for the guide mechanism 30T and the guide mechanism 30AS, a typical mechanism is usable.

(124) The movement member 31S having only the hydrostatic pressure guide mechanism 40 to be used for the guide mechanism 30S for tilt prevention can be arranged as follows.

(125) In FIG. 13, a surface of each of the thick stepped portions on both ends of the movement member 31S is defined as the smooth surface 49. Two hydrostatic pressure guide mechanisms 40 are formed on the smooth surface 49.

(126) The arrangement of the hydrostatic pressure guide mechanism 40 is the same as that in the first exemplary embodiment. Duplicated description will be omitted.

(127) In the above guide mechanism 30S, the movement member 31S includes four hydrostatic pressure guide mechanisms 40 in total, whereby a large load can be received between the guide mechanism 30S and the first rail 141S (the guide member).

Other Exemplary Embodiment

(128) It should be understood that the scope of the invention is not limited to the above-described exemplary embodiments but includes modifications and improvements as long as the modifications and improvements are compatible with an object of the invention.

(129) For instance, the number, layout, size and the like of the hydrostatic pressure guide mechanism 40 to be provided to each component can be determined as desired when the invention is implemented. For instance, a plurality of hydrostatic pressure guide mechanisms 40 may be juxtaposed relative to a single guide mechanism 30.

(130) In the fourth exemplary embodiment, the guide mechanism 30S (movement member 31S) for tilt prevention includes only the hydrostatic pressure guide mechanism 40 and the guide mechanism 30T and guide mechanism 30AS for supporting load includes only the sliding guide mechanism 50. However, a combination of the hydrostatic pressure guide mechanism 40 and the sliding guide mechanism 50 may be used in each of the guide mechanisms.

(131) In the above exemplary embodiments, the lubricating oil supply device 60 includes the passage for supplying and recovering the lubricating oil to and from the hydrostatic pressure guide mechanism 40, and in addition, includes the passage for supplying the lubricating oil to the sliding guide mechanism 50.

(132) However, when it is not necessary to supply the lubricating oil to the sliding guide mechanism 50, the function of supplying the lubricating oil to the sliding guide mechanism 50 may be omitted. For instance, when the amount of the lubricating oil overflowing from the hydrostatic pressure guide mechanism 40 is equal to the amount of the lubricating oil required in the sliding guide mechanism 50, the lubricating oil may be flowed from a part of the seal portion 42 of the hydrostatic pressure guide mechanism 40 to be supplied to the sliding guide mechanism 50.

(133) The sliding guide mechanism 50 is not limited to the sliding guide mechanism in which the same lubricating oil as in the hydrostatic pressure guide mechanism 40 is used for lubrication and wear prevention. A sliding guide mechanism using other oil and fat or using a solid lubricating material as the slide surface 51 may be employed. In such an arrangement, since the seal portion 42 can prevent the lubricating oil from leaking from the hydrostatic pressure guide mechanism 40, the sliding guide mechanism 50 is not adversely affected by leakage of the lubricating oil.

(134) In the above exemplary embodiments, the guide surface 39 is provided to each of the first and second rails 141 and 142 (the guide member) and the guide surface 39 is used in common between the hydrostatic pressure guide mechanism 40 and the sliding guide mechanism 50 of the movement member 31. However, the common use of the guide surface 39 is not a requisite. Two rows of the guide surfaces 39 may be provided on the guide member, in which the respective guide surfaces 39 may be used for the hydrostatic pressure guide mechanism 40 and the sliding guide mechanism 50.

(135) Alternatively, it is not a requisite to collectively provide the hydrostatic pressure guide mechanism 40 and the sliding guide mechanism 50 on the movement member 31. For instance, the hydrostatic pressure guide mechanism 40 and the guide surface (for slide guide) may be provided on the movement member 31 while the sliding guide mechanism 50 and the guide surface (for hydrostatic pressure guide) may be provided on the guide member (the first and second rails 141 and 142 in the above exemplary embodiments).

(136) In the hydrostatic pressure guide mechanism 40 according to the above exemplary embodiments, a circulation type hydrostatic structure is employed in which the lubricating oil is supplied from the supply passage 43 to the static pressure chamber 41, the lubricating oil discharged from the static pressure chamber 41 is recovered from the recovery passage 44, and the recovered lubricating oil is returned to the tank 61. However, the structure of the hydrostatic pressure guide mechanism 40 is not limited to a circulation type hydrostatic structure, but may be a simple flow type hydrostatic structure. For instance, without returning the recovered lubricating oil from the recovery passage 44 to the tank 61, the lubricating oil may be supplied from the supply passage 43 to the static pressure chamber 41 to generate static pressure in the static pressure chamber 41, and subsequently the lubricating oil may be recovered only by the recovery passage 44.

(137) Further, the structure of the hydrostatic pressure guide mechanism 40 may be an encapsulation type hydrostatic structure in which the static pressure of the lubricating oil stored in the static pressure chamber 41 is used. Also in this arrangement, the supply passage 43 needs to be provided in order to maintain the amount and the pressure of the lubricating oil in the static pressure chamber 41 at respective predetermine values. However, the recovery passage 44 can be omitted.

(138) The above exemplary embodiments relate to an instance where the guide mechanism of the invention is applied to the Y-axis movement mechanism 22 for relatively moving the cross bar 14 and the head 15 in the machine tool 10 having a portal supporting structure including a pair of columns 13 and the cross bar 14. However, the guide mechanism of the invention is not limited to application to such components, but may be applied to other relatively movable portions of the machine tool 10, for instance, the guide mechanism of the Z-axis movement mechanism 23 that relatively moves the head 15 and the ram 16 or the guide mechanism of the X-axis movement mechanism 21 that relatively moves the platform 11 and the table 12.

(139) In FIG. 1 above, a pair of guide mechanisms capable of mainly receiving the load of the table 12 are provided as the X-axis movement mechanism 21 on an upper surface of the platform 11. A guide mechanism capable of restricting the moving direction of the table 12 relative to the platform 11 may be provided on a vertical inner wall of a recess between the guide mechanisms.

(140) As shown in FIG. 14, a guide mechanism 30W for supporting load includes a guide member 31W on a lower surface of the table 12. An upper surface of the platform 11 is the guide surface 39W against the guide member 31W. A guide mechanism 30G for restricting the moving direction includes a pair of guide members 31G on both sides of a recess formed on the lower surface of the table 12. A pair of inner surfaces of a groove formed in the platform 11 are the guide surfaces 39G against the guide members 31G.

(141) Among the above arrangements, since the load received by the guide mechanism 30W for supporting the load is substantially the weight of the table 12 and the weight of the workpiece 19 (see FIG. 1), the sliding guide mechanism 50 is usable.

(142) On the other hand, the guide mechanism 30G for restricting the moving direction occasionally receives in a horizontal direction a cutting force much larger than the above weights of the table 12 and the workpiece 19, in which the force exceeds an allowable surface pressure of the sliding guide mechanism 50. For this reason, the guide mechanism 30G for restricting the moving direction can receive a high load using the hydrostatic pressure guide mechanism 40.

(143) Thus, the hydrostatic pressure guide mechanism 40 and the sliding guide mechanism 50 may be selectively used depending on requisite conditions of the guide mechanism for each of the components (e.g., the guide mechanism 30W for supporting the load and the guide mechanism 30G for restricting the moving direction).

(144) Further, the guide mechanism of the invention may be applied not only to the guide mechanism for linear movement but also to the guide mechanism at a rotary portion (e.g., a rotary support mechanism of a rotary table).

(145) The machine tool to which the guide mechanism of the invention is applied is not limited to the machine tool 10 but is applicable to various machine tools having two relatively movable members.