lathe

Abstract

To provide a lathe with high process tolerance.SOLUTION: A lathe comprises: a first main spindle 31 which grips a work-piece W1, and is rotatable around a first main spindle center line CL1; a first cutter holder 5 to which a tool T1, that cuts in the work-piece W1 gripped by the first main spindle 31 thereby processing the work-piece W1, is attached; an X1 axis ball screw 502 which extends in an X1 axis direction orthogonal to the first main spindle center line CL1, and moves the first cutter holder 5 in the X1 axis direction; and an X1 axis support bearing 504 which is located on one end side part of the X1 axis ball screw 502 in the X1 axis direction, and regulates movement of the X1 axis ball screw 502 in X1 axis direction. The first cutter holder 5 has an X1 axis ball screw nut 512 which engages with the X1 axis ball screw 502, and is moved along the X1 axis direction by rotation of the X1 axis ball screw 502. A cut-in direction of the tool T1 is a direction in which the X1 axis ball screw nut 512 approaches the X1 axis support bearing 504.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to a lathe equipped with a spindle and a tool rest. [Background technology]

[0002] There is known a lathe equipped with a spindle capable of gripping and rotating a workpiece, and a tool rest on which a tool for machining the workpiece gripped by the spindle is provided (see, for example, Patent Document 1, etc.). The lathe described in Patent Document 1 machines the workpiece gripped by the spindle and rotating by moving the tool rest in the cutting direction in which the tool cuts into the workpiece. The tool rest is provided with a driven part. The driven part is meshed with a drive shaft whose axial movement is restricted by a movement restricting part. When the drive shaft rotates around its axis, the driven part moves in its axial direction. Since the axial direction of the drive shaft is oriented in the cutting direction, when the drive shaft rotates by receiving the driving force of the motor, the tool rest moves in the cutting direction or the opposite direction depending on the rotation direction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special table 2002-509489 publication Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the lathe described in Patent Document 1, when the tool post moves in the cutting direction and the tool cuts into the workpiece, there is a large gap between the movement restricting part that restricts the movement of the drive shaft and the driven part of the tool post. Therefore, when the drive shaft expands and contracts in its axial direction due to heat, the amount of cutting of the tool changes, resulting in a problem of reduced machining accuracy.

[0005] The present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to provide a lathe with high machining accuracy. [Means for solving the problem]

[0006] The lathe of the present invention which solves the above object comprises: A spindle capable of gripping a workpiece and rotating about a spindle center line; a tool rest on which a tool is mounted for cutting into the workpiece held by the spindle to machine the workpiece; a drive shaft that extends in an axial direction perpendicular to a center line of the spindle and rotates to move the tool rest in the axial direction; a movement restricting portion disposed at one end portion of the drive shaft in the axial direction and restricting movement of the drive shaft in the axial direction; a motor that rotates the drive shaft, the motor is disposed on a front side of the lathe where an operation panel is provided, relative to the tool rest; the tool rest is disposed on a rear side of the lathe, opposite to the front side, with respect to a center line of the spindle, and has a driven part that meshes with the drive shaft and moves in the axial direction by rotation of the drive shaft, The cutting direction of the tool is a direction in which the driven part approaches the movement restricting part. The tool rest may be configured so that the tools are mounted in a vertical line and move vertically to select the tool to be cut into the workpiece. moreover, A spindle capable of gripping a workpiece and rotating about a spindle center line; a tool rest on which a tool is mounted for cutting into the workpiece held by the spindle to machine the workpiece; a drive shaft extending in an axial direction perpendicular to a center line of the spindle and configured to move the tool rest in the axial direction; a movement restricting portion disposed at one end portion of the drive shaft in the axial direction and restricting movement of the drive shaft in the axial direction, the tool rest has a driven part that meshes with the drive shaft and moves in the axial direction by rotation of the drive shaft, The cutting direction of the tool is a direction in which the driven part approaches the movement restricting part. It may also be .

[0007] According to this lathe, when the tool moves in the cutting direction, the driven part approaches the movement restricting part, so that the movement restricting part and the driven part are positioned close to each other when machining the workpiece. As a result, even if the drive shaft expands or contracts in its axial direction due to heat, the amount of cutting of the tool into the workpiece is unlikely to change, thereby improving the machining accuracy of the workpiece.

[0008] Here, the lathe may include a guide bush in front of the spindle for supporting the workpiece rotatably around the center line of the spindle. The drive shaft may be a ball screw, and the driven part may be a ball screw nut meshed with the ball screw. Furthermore, the movement restricting part may be a rolling bearing. In addition, the lathe may include a motor for rotating the drive shaft, and the cutting direction of the tool may be a direction in which the driven part approaches the motor. Furthermore, the output shaft of the motor and the drive shaft may be arranged on the same axis.

[0009] In this lathe, the driven part may be disposed on a portion of the tool rest on the cutting direction side.

[0010] In this way, the driven part is disposed close to the movement restricting part, so that even if the drive shaft extends or contracts in its axial direction, the amount of cutting of the tool into the workpiece is unlikely to change, thereby further improving the machining accuracy of the workpiece.

[0011] The lathe includes a motor that rotates the drive shaft, The motor may be disposed on the cutting direction side of the tool rest.

[0012] If the motor is disposed on the opposite side of the cutting direction from the tool rest, the tool rest and the motor are disposed side by side on one side of the spindle that grips the workpiece, which tends to increase the size of the lathe. By disposing the motor in this manner, the lathe can be made smaller.

[0013] The lathe further includes a motor for rotating the drive shaft, the tool rest is disposed on the back side of the lathe with respect to the center line of the spindle, The motor may be disposed closer to the front of the lathe than the tool rest.

[0014] If the motor is disposed on the rear side of the tool post, which is disposed on the rear side of the spindle center line, the motor and its support structure would protrude to the rear side, which would tend to increase the size of the lathe. According to this aspect, the motor is disposed on the front side of the tool post, which makes it possible to reduce the size of the lathe.

[0015] The lathe further includes a motor for rotating the drive shaft, the tool rest is disposed on a front side of the lathe with respect to a center line of the spindle, The motor may be disposed on the rear side of the lathe relative to the tool rest.

[0016] If the motor is disposed further forward than the tool rest, which is disposed further forward than the center line of the spindle, the motor and its support structure would protrude toward the front side, making the lathe larger. According to this embodiment, the motor is disposed on the rear side of the tool rest, making it possible to reduce the size of the lathe.

[0017] Here, the motor may be disposed above the main shaft, and the motor may be a servo motor. Effect of the Invention

[0018] According to the present invention, a lathe with high machining accuracy can be provided. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a perspective view showing the appearance of an NC lathe according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a front view showing the appearance of the NC lathe shown in FIG. [Diagram 3] 2 is a plan view showing a simplified internal configuration of the NC lathe shown in FIG. 1. [Figure 4] FIG. 2 is a rear view showing the appearance of the NC lathe shown in FIG. [Diagram 5]5 is a perspective view of the switchboard room shown in FIG. 4, seen obliquely from above on the front side. [Figure 6] FIG. 2 is a front view showing the inside of the NC lathe shown in FIG. 1 with a part of the front exterior cut away. [Figure 7] 3 is a right side view of the tool rest base, the first tool rest, and the guide bush of the NC lathe shown in FIG. 1 as viewed from the right side in FIG. 2. [Figure 8] FIG. 2A is a plan view showing a simplified configuration of the tool post base and the lower part of the first tool post of the NC lathe shown in FIG. 1, and FIG. 2B is a plan view showing the state in which the intermediate base has moved in the -X1 direction from the state shown in FIG. 2A. [Figure 9] FIG. 8 is a right side view similar to FIG. 7, showing a modified example of the NC lathe. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In this embodiment, the present invention will be described by taking an example in which the present invention is applied to an NC (Numerical Control) lathe.

[0021] Fig. 1 is a perspective view showing the appearance of an NC lathe according to this embodiment, and Fig. 2 is a front view showing the appearance of the NC lathe shown in Fig. 1.

[0022] As shown in FIG. 1 and FIG. 2, the NC lathe 1 is provided with a cutting chamber 11, a headstock chamber 12, and an operation panel 15 on legs serving as a base. This NC lathe 1 corresponds to an example of a lathe. In FIG. 1, the left front side of the figure is the front side of the NC lathe 1, and the right rear side of the figure is the rear side of the NC lathe 1. In addition, FIG. 2 also shows the downstream end of a discharge conveyor 9 that conveys a product that has been machined by the NC lathe 1 to the outside of the NC lathe 1. The cutting chamber 11 is disposed on the right side of the NC lathe 1 as viewed from the front side. A window 111 is provided on the front side of the cutting chamber 11 for visually observing the inside of the cutting chamber 11. The headstock chamber 12 is disposed on the left side of the NC lathe 1 as viewed from the front side. The cutting chamber 11 and the headstock chamber 12 are spaced apart from each other, and a guide bush support table 41 (see FIG. 3) and a first tool rest 5 (see FIG. 3), which will be described later, are disposed between them. Hereinafter, the portion between the cutting chamber 11 and the headstock chamber 12 will be referred to as the middle section. The front side of the middle section is covered with a tool rest front cover 131. The upper end of the middle section is covered with a tool rest ceiling cover 132. The tool rest ceiling cover 132 has a plurality of louvers 1322 formed thereon. The tool rest front cover 131 and the tool rest ceiling cover 132 protrude slightly from the middle section toward the cutting chamber 11. Therefore, the tool rest front cover 131 and the tool rest ceiling cover 132 also cover the left end portion of the cutting chamber 11 in FIG. 2. The operation panel 15 is disposed above the headstock chamber 12. The operation panel 15 is an input device for operating the NC lathe 1. The operator of the NC lathe 1 operates the NC lathe 1 using the operation panel 15 while visually checking the machining operation and the like by looking into the cutting chamber 11 through the window 111 for operation confirmation in new machining and the like. At that time, the machining operation and the like may be adjusted by repeatedly viewing the inside of the cutting chamber 11 and operating the operation panel 15. In the present embodiment, the tool post front cover 131 has a large chamfered shape 131a formed between the front portion of the tool post front cover 131 that protrudes toward the front side and the side portion on the operation panel 15 side, so that when the operator of the NC lathe 1 moves his / her line of sight from the cutting chamber 11 to the operation panel 15 or vice versa, the tool post front cover 131 is unlikely to get in the way, and the operator can quickly move his / her line of sight.In addition, when an operator of the NC lathe 1 reaches out to operate the operation panel 15 while looking at the window 111, or when the operator reaches out to operate the operation panel 15 while moving from the cutting chamber 11 side to the operation panel 15 side, the tool post front cover 131 is less likely to impede hand movement, improving the operability of the NC lathe 1.

[0023] FIG. 3 is a plan view showing a simplified internal configuration of the NC lathe shown in FIG.

[0024] As shown in FIG. 3, the NC lathe 1 includes an NC unit 2, a first headstock 3, a guide bush 4, a first tool rest 5, a second headstock 6, and a tool rest for the second spindle 7. An NC program is stored in the NC unit 2. The NC unit 2 is a computer that moves the first headstock 3, the first tool rest 5, the second headstock 6, and the tool rest for the second spindle 7 by numerical control according to the NC program. In addition, a rotating tool that rotates the tool T1 itself may be attached to the first tool rest 5, and similarly, a rotating tool that rotates the tool T2 itself may be attached to the tool rest for the second spindle 7. In that case, the NC unit 2 also controls the rotation of the rotating tool. In addition to the operation using the NC program, the NC lathe 1 can also be operated by directly inputting commands to the NC unit 2 from the operation panel 15 shown in FIG. 1.

[0025] The first spindle stock 3 is disposed in the spindle stock room 12 shown in FIG. 1. The first spindle stock 3 is mounted with the first spindle 31. The first spindle 31 corresponds to an example of a spindle. The first spindle stock 3 can move in the Z1 axis direction together with the first spindle 31. The Z1 axis direction is a horizontal direction, which is a left-right direction in FIG. 3. In the following description, for convenience, the right side in FIG. 3 is referred to as the "front" and the left side in FIG. 3 is referred to as the "rear". In addition, in this NC lathe 1, the front direction coincides with the +Z1 direction, and the rear direction coincides with the -Z1 direction. The first spindle 31 has a first gripping portion such as a collet at its front end. In addition, the first spindle 31 releasably grips the rod-shaped workpiece W1 inserted into the inside of the first spindle 31 from its rear end with the first gripping portion. The first spindle 31 can rotate around the first spindle center line CL1 while gripping the workpiece W1. This first spindle center line CL1 corresponds to an example of a spindle center line. The direction of the first spindle center line CL1 coincides with the Z1 axis direction. The first spindle 31 is provided with a motor such as a built-in motor. When the motor receives a command from the NC device 2, the first spindle 31 rotates about the first spindle center line CL1. As a result, the workpiece W1 gripped by the first spindle 31 rotates about the first spindle center line CL1.

[0026] The guide bush 4 is fixed to the leg of the NC lathe 1 by the guide bush support base 41 in front of the first spindle 31. The guide bush 4 supports the front end side portion of the workpiece W1 that penetrates the inside of the first spindle 31 so that it can slide freely in the Z1 axis direction. The portion of the guide bush 4 that supports the workpiece W1 can rotate around the first spindle center line CL1 in synchronization with the first spindle 31. In other words, the first spindle center line CL1 is also the rotation center line of the workpiece W1 supported by the guide bush 4. The guide bush 4 suppresses the deflection of the workpiece W1 during processing, so that the elongated workpiece W1 in particular can be processed with high precision. The front portion of the guide bush 4 is exposed in the cutting chamber 11.

[0027] The first tool rest 5 is disposed on the rear side of the NC lathe 1 relative to the first spindle center line CL1. The first tool rest 5 is movable in the X1-axis direction, which is perpendicular to the Z1-axis direction and faces horizontally, and in the Y1-axis direction, which faces vertically. The first tool rest 5 corresponds to an example of a tool rest. In FIG. 3, the up-down direction is the X1-axis direction, and the direction perpendicular to the paper surface is the Y1-axis direction. A tool T1 for machining a workpiece W1 is attached to the first tool rest 5. FIG. 3 shows the state in which the tool T1 is attached to the first tool rest 5. A plurality of types of tools T1, including a cutting tool for cutting and the like, are attached to the first tool rest 5 in the Y1-axis direction. An arbitrary tool T1 is selected from the plurality of types of tools T1 by moving a first tool rest table 52 (see FIG. 7) (described later) provided on the first tool rest 5 in the Y1-axis direction. As the first tool rest 5 moves in the cutting direction, the tool T1 cuts into the workpiece W1 held by the first spindle 31 to machine the workpiece W1. In this embodiment, the cutting direction of the tool T1 is the front direction of the NC lathe 1, which is shown as the -X1 direction in FIG. 3. The configuration of the first tool rest 5 will be described in detail later. Most of the first tool rest 5 except for its front portion is disposed in the middle section, but the front portion and the tool T1 are disposed in the cutting chamber 11.

[0028] The second spindle stock 6 is located in front of the guide bush 4 and is disposed in the cutting chamber 11 shown in FIG. 1. The second spindle stock 6 is mounted with a second spindle 61. The second spindle stock 6 can move together with the second spindle 61 in the X2-axis direction and the Z2-axis direction. The X2-axis direction is the same as the X1-axis direction described above, and the Z2-axis direction is the same as the Z1-axis direction described above. The second spindle 61 has a second gripping portion such as a collet at its rear end. The tip of the workpiece W1 after machining using the first spindle 31 is chucked by the second spindle 61, and the first spindle 31 and the second spindle 61 are rotated synchronously to perform a cutting operation using a cutting-off tool. Alternatively, the workpiece after machining using the first spindle 31 is chucked by the second spindle 61, and the second spindle 61 is rotated with the chuck of the first spindle 31 open to perform a cutting operation using a cutting-off tool. As a result, the cut workpiece W2 is transferred to the second spindle 61. The second spindle 61 releasably holds the cut workpiece W2 transferred from the first spindle 31 by the second gripping portion. The second spindle 61 can hold the cut workpiece W2 and rotate around the second spindle center line CL2. The direction of the second spindle center line CL2 coincides with the Z2 axis direction. The second spindle 61 is provided with a motor such as a built-in motor. When the motor receives a command from the NC device 2, the second spindle 61 rotates around the second spindle center line CL2. As a result, the cut workpiece W2 held by the second spindle 61 rotates around the second spindle center line CL2. The second spindle 61 is sometimes called the counter spindle because it is arranged to face symmetrically with the first spindle 31.

[0029] The second spindle tool rest 7 is disposed slightly forward of the guide bush 4 and at a position shifted toward the front side of the NC lathe 1 with respect to the guide bush 4 and the first spindle center line CL1. The second spindle tool rest 7 is movable in the Y2-axis direction. This Y2-axis direction is the same as the Y1-axis direction described above. The second spindle tool rest 7 is fitted with a tool T2 for machining the cut workpiece W2 held by the second spindle 61. FIG. 3 shows the state in which the tool T2 is fitted to the second spindle tool rest 7. The second spindle tool rest 7 is also equipped with a receiving device (not shown) for receiving the workpiece after machining. A plurality of types of tools T2, such as drills and end mills, are attached to the second spindle tool rest 7 in a line. Although not shown in FIG. 3, the tools T2 are attached in a line not only in the X2-axis direction but also in the Y2-axis direction. By moving the second spindle tool rest 7 in the Y2-axis direction, an arbitrary tool T2 is selected from the multiple types of tools T2. Then, by moving the second spindle stock 6 in the -Z direction, the rear end portion of the cut workpiece W2 held by the second spindle 61 is machined. The second spindle tool rest 7 is disposed in the cutting chamber 11 shown in FIG.

[0030] FIG. 4 is a rear view showing the appearance of the NC lathe shown in FIG.

[0031] As shown in FIG. 4, a switchboard room 14 is provided in the lower part of the back of the NC lathe 1. The switchboard room 14 is usually covered by a switchboard cover 141. FIG. 4 shows a state in which the switchboard cover 141 is removed and moved to the right side of the figure as indicated by the arrow. As shown in the enlarged view circled in FIG. 4, a plurality of electrical equipment units 142 in which amplifiers, controllers, etc. are unitized are arranged in the switchboard room 14. These electrical equipment units 142 are screwed at the front side of the page in FIG. 4, and the electrical equipment units 142 can be removed to the front side of the page in FIG. 4 by removing the screws. This allows the necessary electrical equipment units 142 to be removed from the switchboard room 14 when the electrical equipment units 142 are maintained or broken. In addition, cables 143 connected to various actuators and electrical components provided in the NC lathe 1 are connected to these electrical equipment units 142. 4, only the portion of the cable 143 that is in the vicinity of the switchboard room 14 is shown, and the rest is omitted. The cable 143 passes through cable entry parts 145 provided on each of the left and right sides of the switchboard room 14 and is connected to the electrical unit 142 in the switchboard room 14.

[0032] FIG. 5 is a perspective view of the switchboard room shown in FIG. 4, seen obliquely from above on the front side.

[0033] As shown in FIG. 5, the cable entry section 145 is composed of an entry stopper 1451, an upper holding body 1452, and a lower holding body 1453. The entry stopper 1451, the upper holding body 1452, and the lower holding body 1453 are fixed to the side of the switchboard room 14 with screws. The upper holding body 1452 and the lower holding body 1453 are arranged facing each other in the vertical direction, and the facing parts are each formed of a sponge-like material. The cable 143 is sandwiched between the sponge-like material of the upper holding body 1452 and the sponge-like material of the lower holding body 1453. In addition, the lower holding body 1453 is provided with a holding metal fitting having an Ω-shaped groove formed therein for fixing the part of the cable 143 drawn out of the switchboard room 14 with a cable tie. The lower holder 1453 can be removed from the switchboard chamber 14 by removing the entry stopper 1451 from the switchboard chamber 14 and then unscrewing the screws. FIG. 5 shows a state in which the entry stopper 1451 is removed and the lower holder 1453 of the upper cable entry section 145 is removed. By configuring the lower holder 1453 to be removable from the switchboard chamber 14, it is possible to prevent the cable 143 from getting in the way when removing one of the electrical equipment units 142 (see FIG. 4) located near the side from the switchboard chamber 14. In other words, the electrical equipment unit 142 can be easily removed from the switchboard chamber 14, improving maintainability.

[0034] FIG. 6 is a front view showing the inside of the NC lathe shown in FIG. 1 with a part of the front exterior cut away.

[0035] As shown in FIG. 6, the upper end of the first tool rest 5 is covered by a tool rest ceiling cover 132. In addition, an intermediate wall 133 is formed between the cutting chamber 11 and the intermediate section. In the cutting chamber 11, a large amount of coolant is discharged mainly toward the machining part for the purpose of smooth machining and cooling the heat caused by machining. The coolant discharged into the cutting chamber 11 is collected and circulated in the NC lathe 1. The intermediate section and the cutting chamber 11 are separated by the intermediate wall 133 and the front surface of the first tool rest 5. Therefore, the coolant is basically prevented from flowing into the intermediate section or the headstock chamber 12. However, liquid or mist-like coolant may enter the tool rest ceiling cover 132 through a gap at the upper end of the first tool rest 5. As described above, the tool rest ceiling cover 132 is formed with a plurality of louvers 1322 for exhausting air inside the NC lathe 1. Therefore, if the coolant liquid enters the tool rest ceiling cover 132, there is a risk that the coolant liquid will flow out of the NC lathe 1, which may cause odors and stickiness in the area around the NC lathe 1. There is also a risk that the coolant liquid will enter the headstock chamber 12 via the intermediate portion. If the coolant liquid enters the headstock chamber 12, it may shorten the life of the first headstock 3 and the first spindle 31 shown in FIG. 3, and may become sticky and difficult to maintain. In this embodiment, a partition plate 1321 is formed hanging down from the top surface of the tool rest ceiling cover 132 near the center in the Z1 axis direction, and a louver 1322 is formed only on the rear (-Z1 direction) side of the partition plate 1321. With this arrangement, even if coolant does enter the tool rest ceiling cover 132, it is blocked by the partition plate 1321 and is unlikely to enter behind the partition plate 1321. As a result, the coolant is prevented from leaking out of the NC lathe 1 or from entering the headstock chamber 12.

[0036] Fig. 7 is a right side view of the tool rest base, the first tool rest, and the guide bush of the NC lathe shown in Fig. 1, as viewed from the right side in Fig. 2. In Fig. 7, the outline of the NC lathe 1 is indicated by a dashed line.

[0037] As shown in FIG. 7, the first tool rest 5 is disposed on the tool rest base 50. The first tool rest 5 has a first intermediate base 51 movable in the X1-axis direction and a first tool rest table 52 mounted on the first intermediate base 51 and movable in the Y1-axis direction. The first tool rest table 52 is disposed forward of the first intermediate base 51. In FIG. 7, the direction perpendicular to the paper surface is the Z1-axis direction, and the front side of the paper surface is the front side. The first intermediate base 51 of the first tool rest 5 is disposed in the intermediate portion, and the front part of the first tool rest table 52 is disposed in the cutting chamber 11. The tool rest base 50 is fixed on a leg (not shown) that is a base. The first intermediate base 51 is attached to the tool rest base 50 so as to be movable in the X1-axis direction. The first tool rest table 52 is attached to the first intermediate base 51 so as to be movable in the Y1-axis direction. A Y1-axis ball screw nut (not shown) is fixed to the first tool rest table 52. A Y1-axis ball screw (not shown) is connected to the output shaft of a Y1-axis motor (not shown). The Y1-axis ball screw has a spiral groove formed on its outer periphery. Balls circulate inside the Y1-axis ball screw nut, and the balls mesh (screw) with grooves provided in the Y1-axis ball screw. By driving the Y1-axis motor (not shown), the Y1-axis ball screw rotates, and the first tool post table 52 moves in the Y1-axis direction. FIG. 7 shows the first tool post table 52 located at the origin position in the Y1-axis direction. The tool post base 50 and the guide bush support base 41 may be integrally configured.

[0038] An X1-axis motor 501 is fixed to the tool rest base 50. This X1-axis motor 501 corresponds to an example of a motor. The X1-axis motor 501 is disposed closer to the front side of the NC lathe 1 than the first tool rest 5. The X1-axis motor 501 is disposed above the guide bush 4 and the first spindle 31 (see FIG. 3). An X1-axis ball screw 502 disposed on the same axis is connected to an X1 output shaft 5011 (see FIG. 8) of the X1-axis motor 501. This connection structure will be described in detail later. By supplying power to a stator in the X1-axis motor 501, the X1 output shaft 5011 rotates together with the rotor, and the X1-axis ball screw 502 connected to the X1 output shaft 5011 rotates. The X1-axis ball screw 502 extends in a direction perpendicular to the first spindle center line CL1, and a spiral groove is formed on the outer periphery. Specifically, the X1-axis ball screw 502 extends in the X1-axis direction. This X1-axis direction corresponds to an example of an axial direction, and the X1-axis ball screw 502 corresponds to an example of a drive shaft. The first intermediate base 51 has an X1-axis ball screw nut 512. This X1-axis ball screw nut 512 corresponds to an example of a driven part. The X1-axis ball screw nut 512 has balls circulating therein, and the balls mesh with grooves provided in the X1-axis ball screw 502. Then, the X1-axis motor 501 is driven to rotate the X1-axis ball screw 502, whereby the first intermediate base 51 moves in the X1-axis direction. FIG. 7 shows the first intermediate base 51 located at the origin position in the X1-axis direction.

[0039] Next, the configuration and operation of the first tool rest will be described in more detail.

[0040] Fig. 8(a) is a plan view showing a simplified configuration of the tool rest base and the lower part of the first tool rest of the NC lathe shown in Fig. 1. Fig. 8(a) shows the intermediate base positioned at the origin position in the X1 axis direction, as in Fig. 7. Fig. 8(b) is a plan view showing the intermediate base moved in the -X1 direction from the state shown in Fig. 8(a). Note that Fig. 8(a) shows the guide bush 4 and the workpiece W1 in broken lines, and Fig. 8(b) shows the guide bush 4 and the cut workpiece W2 in broken lines.

[0041] As shown in FIG. 8(a), the first tool rest table 52 has a table base 520, a tool fixing portion 521 to which the tool T1 is fixed, and a Y1-axis slide portion 522. The table base 520 is a core member of the first tool rest table 52 to which the tool fixing portion 521 and the Y1-axis slide portion 522 are fixed. The first intermediate base 51 has a base base 510, an X1-axis slide portion 513, and a Y1-axis rail 514 in addition to the above-mentioned Y1-axis motor and X1-axis ball screw nut 512. The base base 510 is a core member of the first intermediate base 51 to which other members of the first intermediate base 51 are fixed. The Y1-axis rail 514 extends in the Y1-axis direction perpendicular to the paper surface of FIG. 8(a). The Y1-axis slide portion 522 is slidably attached to the Y1-axis rail 514. As a result, the first tool rest table 52 is disposed so as to be freely movable in the Y1-axis direction relative to the first intermediate base 51, and is moved in the Y1-axis direction by the driving of the Y1-axis motor as described above.

[0042] An X1-axis rail 505 is fixed to the tool rest base 50. The X1-axis rail 505 extends in the X1-axis direction. The X1-axis slide portion 513 is slidably attached to the X1-axis rail 505. As a result, the first intermediate base 51 is arranged to be movable in the X1-axis direction relative to the tool rest base 50. An X1-axis coupling 503 is arranged in the tool rest base 50. The X1-axis coupling 503 connects the X1 output shaft 5011 of the X1-axis motor 501 to the X1-axis ball screw 502. An X1-axis support bearing 504 is also arranged in the tool rest base 50. The X1-axis support bearing 504 corresponds to an example of a movement restricting portion. The X1-axis support bearing 504 is arranged at one end side portion in the axial direction of the X1-axis ball screw 502. The X1-axis support bearing 504 is a so-called rolling bearing having a rolling element between an outer ring and an inner ring. The outer ring of the X1-axis support bearing 504 is fixed to the tool rest base 50, and the X1-axis ball screw 502 is fixed to the inner ring. As a result, the X1-axis ball screw 502 is fixed to the tool rest base 50 so as to be rotatable about the X1-axis direction. In other words, the X1-axis ball screw 502 is restricted in movement other than rotation about the X1-axis direction by the X1-axis support bearing 504. When the X1-axis ball screw 502 rotates in a state in which movement in the X1-axis direction is restricted, the X1-axis ball screw nut 512 meshing with the X1-axis ball screw 502 moves in the +X1 direction or the -X1 direction depending on the rotation direction. As a result, the first intermediate base 51 moves in the same direction as the X1-axis ball screw nut 512 together with the first tool rest table 52. In other words, the first tool rest 5 moves in the +X1 direction or the -X1 direction.

[0043] As shown in FIG. 8(b), when the X1-axis motor 501 is driven to move the first tool rest 5 in the -X direction, the tool T1 cuts into the workpiece W1. That is, this -X direction corresponds to an example of a cutting direction. The -X direction is the direction in which the X1-axis ball screw nut 512 approaches the X1-axis support bearing 504. The -X direction is also the direction in which the X1-axis ball screw nut 512 approaches the X1-axis motor 501. A cut-off cutting tool is used as the tool T1, and the tip of the cut-off cutting tool reaches the first spindle center line CL1, cutting the workpiece W1. FIG. 8(b) shows a state in which the cutting edge of the tool T1 reaches the first spindle center line CL1 and the front part of the workpiece W1 is cut to become the cut workpiece W2. Normally, before the workpiece W1 is cut, the second spindle 61 shown in Fig. 3 grips the front portion of the workpiece W1 and then cuts the workpiece W1, so that the cut workpiece W2 is delivered to the second spindle 61. When machining the rear portion (-Z side) of the cut workpiece W2, the cut workpiece W2 is gripped by the second spindle 61 and the rear portion is machined by the tool T2 shown in Fig. 3.

[0044] According to the NC lathe 1 of this embodiment, when the tool T1 moves in the cutting direction, the X1-axis ball screw nut 512 approaches the X1-axis support bearing 504, so that the X1-axis support bearing 504 and the X1-axis support bearing 504 are disposed in close positions when the workpiece W1 is machined. In other words, in the NC lathe 1 of this embodiment, when the tool T1 comes into contact with the workpiece W1 to machine it, the X1-axis ball screw nut 512 approaches the X1-axis support bearing 504. When the workpiece W1 is machined, heat such as frictional heat during cutting is generated, and the X1-axis ball screw 502 may stretch somewhat in the X1-axis direction. In addition, since many products are generally manufactured from a long workpiece W1 from the start to the end of machining, the length of the X1-axis ball screw 502 may differ slightly between the early and late stages of machining, causing the amount of cutting of the tool T1 to change. In the NC lathe 1 described so far, even if the X1-axis ball screw 502 expands and contracts in the X1-axis direction due to heat, the X1-axis ball screw nut 512 and the X1-axis support bearing 504 are close to each other during machining, so that the cutting amount of the tool T1 is unlikely to change, and as a result, the machining accuracy of the workpiece W1 can be improved. Also, if the X1-axis motor 501 is arranged on the rear side of the first tool rest 5, the X1-axis motor 501 and the support structure of the X1-axis motor 501 protrude to the rear side, and the NC lathe 1 is likely to become large. In other words, if the X1-axis motor 501 is arranged on the opposite side of the cutting direction of the tool T1 from the first tool rest 5, the first tool rest 5 and the X1-axis motor 501 are arranged side by side on the rear side of the first spindle, and the NC lathe 1 is likely to become large. In the NC lathe 1 of this embodiment, the first tool rest 5 is disposed on the rear side of the NC lathe 1 relative to the first spindle center line CL1, and the X1-axis motor 501 is disposed on the front side of the NC lathe 1 relative to the first tool rest 5, thereby making the NC lathe 1 compact. In other words, the NC lathe 1 is made compact by disposing the X1-axis motor 501 on the cutting direction side of the tool T1 relative to the first tool rest 5. Furthermore, the X1-axis ball screw nut 512 is disposed on the front side portion (cutting direction side portion) of the first tool rest 5 where the X1-axis motor 501 and the X1-axis support bearing 504 are disposed, so that even if the X1-axis ball screw 502 is short, the first intermediate base 51 can be moved in the X1-axis direction.In addition, since the X1-axis ball screw nut 512 is disposed at the front side portion of the first tool rest 5, the X1-axis ball screw nut 512 is disposed close to the X1-axis support bearing 504, and even if the X1-axis ball screw 502 expands and contracts in the axial direction, the cutting amount of the tool T1 into the workpiece W1 is unlikely to change. This further improves the machining accuracy of the workpiece W1. Furthermore, since the cutting edge of the tool T1 is configured to be disposed at a position overlapping the X1-axis ball screw nut 512 in the X1-axis direction, even if the base substrate 510 and the first tool rest table 52 between the X1-axis ball screw nut 512 and the tool T1 expand and contract in the X1-axis direction due to heat, the cutting edge of the tool T1, which is the machining position, is unlikely to be affected by the expansion and contraction. This also improves the machining accuracy. In addition, if the cutting edge of tool T1 and the X1-axis ball screw nut 512 are close to each other in the X1-axis direction, the machining accuracy will be improved; however, by having the cutting edge of tool T1 and the X1-axis ball screw nut 512 overlap in the X1-axis direction, the machining accuracy is further improved.

[0045] Next, in the following explanation of the modified examples of the NC lathe 1 described so far, components having the same names as components described so far will be given the same symbols as those used so far, and duplicate explanations may be omitted.

[0046] Fig. 9 is a right side view similar to Fig. 7, showing a modified example of the NC lathe. In Fig. 9, the X1-axis coupling 503, the X1-axis support bearing 504, and the X1 output shaft 5011 are also shown by two-dot chain lines.

[0047] As shown in FIG. 9, the NC lathe 1 of this modification is different from the NC lathe 1 shown in FIG. 7 mainly in the positional relationship between the first tool rest 5 and the X1-axis motor 501. In this modification, the first tool rest 5 is disposed on the front side of the NC lathe 1. The X1-axis motor 501 is disposed on the rear side of the NC lathe 1 relative to the first tool rest 5. The X1-axis motor 501 is also disposed above the guide bush 4 and the first spindle 31 (see FIG. 3). The X1-axis ball screw 502 disposed on the same axis is connected to the X1 output shaft 5011 of the X1-axis motor 501. The X1-axis ball screw 502 extends in the X1-axis direction perpendicular to the first spindle center line CL1, and has a spiral groove formed on its outer periphery. FIG. 9 shows the first intermediate base 51 positioned at the origin position in the X1-axis direction.

[0048] When the X1-axis motor 501 is driven to move the first tool rest 5 in the +X direction from the position shown in FIG. 9, the tool T1 cuts into the workpiece W1. That is, in this modified example, the +X direction corresponds to an example of the cutting direction. The +X direction is the direction in which the X1-axis ball screw nut 512 approaches the X1-axis support bearing 504. The +X direction is also the direction in which the X1-axis ball screw nut 512 approaches the X1-axis motor 501. In the modified example described above, the X1-axis ball screw nut 512 is also disposed at the cutting direction side of the first tool rest 5. The X1-axis motor 501 is also disposed at the cutting direction side of the first tool rest 5. The first tool rest 5 is disposed at the front side of the NC lathe 1 at the first spindle center line CL1, and the X1-axis motor 501 is disposed at the rear side of the lathe at the first tool rest 5. This modified example also has the same effects as the previous embodiment.

[0049] The present invention is not limited to the above-mentioned embodiment, and various modifications can be made within the scope of the claims. For example, in this embodiment, the X1 output shaft 5011 of the X1-axis motor 501 and the X1-axis ball screw 502 are arranged on the same axis and directly connected by the X1-axis coupling 503, but the X1 output shaft 5011 and the X1-axis ball screw 502 may be arranged at offset positions and indirectly connected by a drive transmission element such as a drive belt or gear. In addition, the X1-axis direction may be inclined with respect to the horizontal direction, and the Y1-axis direction may be inclined with respect to the vertical direction. Furthermore, the X1-axis direction may be vertical, and the Y1-axis direction may be horizontal.

[0050] In addition, even if a constituent element is included only in the description of each of the modified examples described above, that constituent element may be applied to other modified examples. [Explanation of symbols]

[0051] 1 NC lathe 5 First tool rest (tool rest) 31 1st spindle (main spindle) 502 X1 axis ball screw (drive axis) 504 X1 axis support bearing (movement restriction part) 512 X1 axis ball screw nut (driven part) CL1 1st spindle center line (spindle center line) T1 tool W1 Work

Claims

1. A spindle capable of gripping a workpiece and rotating about a spindle center line; a tool rest on which a tool is mounted for cutting into the workpiece held by the spindle to machine the workpiece; a drive shaft that extends in an axial direction perpendicular to a center line of the spindle and rotates to move the tool rest in the axial direction; a movement restricting portion disposed at one end portion of the drive shaft in the axial direction and restricting movement of the drive shaft in the axial direction; a motor that rotates the drive shaft, the motor is disposed on a front side of the lathe where an operation panel is provided, relative to the tool rest; the tool rest is disposed on a rear side of the lathe, opposite to the front side, with respect to a center line of the spindle, and has a driven part that meshes with the drive shaft and moves along the axial direction by rotation of the drive shaft, A lathe, characterized in that the cutting direction of the tool is a direction in which the driven part approaches the movement restricting part.

2. 2. The lathe according to claim 1, wherein the driven part is disposed on a side of the tool rest in the cutting direction.

3. A lathe as described in claim 1 or 2, characterized in that the motor is arranged on the cutting direction side of the tool post.

4. A lathe as described in any one of claims 1 to 3, characterized in that the tools are mounted in a vertical row and moved vertically to select the tool to cut into the workpiece.

Images