Machine tool

Abstract

In order to provide a machine tool with which the approach of a turret tool is improved, the machine tool includes: a slanted bed on which a forward-slanted upper surface serves as an assembly surface for a device; a first workpiece spindle device that is fixed to the assembly surface of the bed and in which the center line of a spindle is set in a machine body width direction; a second workpiece spindle device that is disposed so as to face the first workpiece spindle device in the machine body width direction on the assembly surface of the bed and that is assembled so as to be movable in the machine body width direction; and a turret device that is disposed behind the second workpiece spindle device on the assembly surface of the bed and that is assembled such that a tool post can move in the machine body width direction and move in a direction along the slant of the assembly surface. The second workpiece spindle device is configured in a straight shape such that the width dimension of a headstock that rotatably supports the spindle is substantially constant in the height direction.

Description

machine tools

[0001] The present invention relates to a machine tool in which a turret tool can be easily brought into contact with a workpiece held by a workpiece spindle device.

[0002] There are various types of machine tools, including twin-spindle lathes with a pair of opposing spindle units, each of which can handle a workpiece via its own spindle chuck. In this case, it is preferable to configure at least one of the spindle units to be movable to allow workpiece handling and machining. Patent Document 1 below discloses a combined lathe incorporating such a configuration. The machine tool described in this document has a first spindle unit mounted on the left side of the bed, and a second spindle unit, coaxial with the first spindle unit and movable axially, mounted on the right side. A turret unit, movable up and down and left and right, is located between the first and second spindle units. Furthermore, this conventional combined lathe has a column installed behind the bed, on which a third spindle unit, movable up and down, left and right, and forward and backward, is mounted.

[0003] Japanese Patent Application Laid-Open No. 2006-263861

[0004] In the above-mentioned conventional example, a movable second spindle unit is mounted on a bed so as to slide on a second spindle guide rail in the machine body width direction (left-right direction), and a similarly movable turret unit is also configured to move relative to the second spindle guide rail. Machine tools configured in this way, sharing the same guide rail, have the advantage of being compact by shortening the machine body's longitudinal dimension. However, since the turret unit is located between the first and second spindle units, each unit is crowded into a small space, which has drawbacks such as limiting the size of the workpiece that can be machined. To solve these problems and create a compact opposed twin-spindle lathe, a slanted bed, in which the mounting surface on which the spindle unit and other components are mounted, is considered. However, machine tools configured in this way have a problem with the approach of the turret unit's turret tool to the workpiece held by the spindle.

[0005] SUMMARY OF THE INVENTION In order to solve the above problems, an object of the present invention is to provide a machine tool with improved accessibility for turret tools.

[0006] A machine tool in one aspect of the present invention comprises a slanted bed with a forward-inclined upper surface as an assembly surface for the device, a first work spindle device fixed to the assembly surface of the bed and with the center line of the spindle set in the width direction of the machine body, a second work spindle device arranged opposite the first work spindle device in the width direction of the machine body on the assembly surface of the bed and assembled so as to be movable in the width direction of the machine body, and a turret device arranged behind the second work spindle device on the assembly surface of the bed and assembled so as to be movable with a tool rest in the width direction of the machine body and in a direction along the slant of the assembly surface, and the second work spindle device is of a straight type in which the width dimension of a headstock that rotatably supports the spindle is substantially constant in the height direction.

[0007] According to the above configuration, the workpiece held by the first workpiece spindle device or the second workpiece spindle device is machined on the assembly surface of the slanted bed by a turret tool attached to the tool post of the turret device, and particularly when the tool post of the turret device moves in a direction along the slope of the assembly surface to machine the workpiece of the second workpiece spindle device, the headstock of the second workpiece spindle device is a straight type whose width dimension is approximately constant in the height direction, so the turret tool can easily approach.

[0008] Fig. 4 is a diagram showing one embodiment of a machine tool, and is a perspective view particularly showing the internal structure of the machine body. Fig. 5 is a perspective view showing the internal structure of the machine tool shown in Fig. 1 , illustrating the assembled state of the second work spindle device and turret device in the machining chamber. Fig. 6 is a side view of the second work spindle device and turret device as seen from inside the machining chamber. Fig. 7 is a side view of the second work spindle device and turret device as seen from inside the machining chamber, with the cover shown in Fig. 3 removed. Fig. 8 is a perspective view of the machine tool in a cross section perpendicular to the Z axis. Fig. 9 is a side view of the machine tool showing a movable cover and a fixed cover in a cross section perpendicular to the Z axis.

[0009] An embodiment of a machine tool according to the present invention will be described below with reference to the drawings. Fig. 1 is a perspective view of the machine tool of this embodiment, particularly showing the internal structure of the machine body. The machine tool 1 of this embodiment is a small NC lathe in which various processing devices for processing a workpiece are assembled on a slant-type bed 6. The forward-inclined upper surface of the bed 6 is an assembly surface 60 of the device, on which are assembled a first workpiece spindle unit 3 that rotatably grips a workpiece, a second workpiece spindle unit 4 that is disposed opposite the first workpiece spindle unit 3 and also rotatably grips a workpiece, and a turret unit 5 that has a plurality of turret tools T.

[0010] First, the first work spindle device 3 is installed in the front left portion of the bed 6. The first work spindle device 3 is assembled so that the center line of its spindle is in the width direction of the machine body and is horizontal, and the second work spindle device 4 is arranged so that its spindle and the first work spindle device 3 are coaxial. In this embodiment, the direction parallel to the spindle of this first work spindle device 3 (the width direction from side to side of the bed 6) will be described as the Z axis. The second work spindle device 4, which is coaxial with the first work spindle device 3, is configured to move in the width direction of the machine body, which is parallel to this Z axis.

[0011] The first work spindle device 3 has a spindle rotatably mounted in a casing 11, and a chuck mechanism 12 integrated with the spindle is rotated by a spindle motor to impart rotation to the gripped workpiece. The second work spindle device 4 is similarly configured to have a rotatable spindle mounted in a casing 15, and a chuck mechanism 16 integrated with the spindle is rotated by a spindle motor. In the first work spindle device 3, the casing 11 that rotatably holds the spindle is integrated with a headstock 13, and the headstock 13 is fixed to the bed 6, but the second work spindle device 4 has a casing 15 mounted on a slidable headstock 14 and is configured to move in the Z-axis direction.

[0012] Two guide rails 18 parallel to the Z-axis are fixed to the front right portion of the mounting surface 60 of the bed 6. The headstock 14 is mounted integrally on a spindle table 17, and a guide block fixed to the underside of the spindle table 17 is configured to mesh with the guide rails 18 and slide. A screw shaft 19 parallel to the Z-axis is journaled between the two guide rails 18, and the rotation shaft of a Z-axis servo motor 20 is connected to the screw shaft 19. A nut member through which the screw shaft 19 passes is fixed to the underside of the spindle table 17, and a ball screw mechanism is configured so that the rotation output of the Z-axis servo motor 20 causes the spindle table 17 to move linearly in the Z-axis direction.

[0013] Next, a turret device 5 is disposed behind the second workpiece spindle device 4. The turret device 5 has a plurality of turret tools T attached at equal intervals in the circumferential direction to a disk-shaped tool rest 21, and the turret tool T to be used for machining can be selected by rotation indexing. The turret device 5 is configured so that the tool rest 21 moves in the Z-axis direction, a vertical direction perpendicular to the Z-axis, and a 45-degree direction that coincides with the inclination of the assembly surface 60. In this embodiment, the vertical direction is referred to as the Y-axis, and the inclination direction of the assembly surface 60 is referred to as the X-axis.

[0014] Two guide rails 23 parallel to the Z axis are fixed to the rear right part of the assembly surface 60, and the turret device 5 has a guide block fixed to the underside of a turret table 24 that slidably engages with the guide rails 23, allowing movement in the Z axis direction by a ball screw mechanism. A screw shaft 25 parallel to the Z axis is supported between the two guide rails 23 via bearings, and the screw shaft 25 passes through a nut member fixed to the underside of the turret table 24. The rotating shaft of a Z axis servo motor 26 is connected to the screw shaft 25, and the rotation output of the screw shaft 25 causes linear movement of the turret table 24 in the Z axis direction.

[0015] A turret X-axis slide 27 is attached to the turret table 24 so as to slide on an X-axis guide rail formed on the upper surface of the turret table 24. A Y-axis guide rail is formed on the vertical front surface of the turret X-axis slide 27, and a turret main body 28, including the tool post 21 and the indexing servo motor 22, is attached to slide on the Y-axis guide rail. A screw shaft (not shown) connected to an X-axis servo motor 29 is supported on the turret table 24 via a bearing, and the screw shaft passes through a nut member fixed to the turret X-axis slide 27. Similarly, a screw shaft (not shown) connected to a Y-axis servo motor 30 is supported on the turret X-axis slide 27 via a bearing, and the screw shaft passes through a nut member fixed to the turret main body 28. Therefore, the rotational outputs of the X-axis servo motor 29 and the Y-axis servo motor 30 cause the turret X-axis slide 27 to move linearly in the X-axis direction, and the turret main body 28 to move linearly in the Y-axis direction.

[0016] The machine tool 1 configured as described above is capable of a first machining operation on a workpiece on the first workpiece spindle device 3 side and a second machining operation on a workpiece on the second workpiece spindle device 4 side. In the first machining operation, the turret tool T, which is swiveled and indexed by the turret device 5, moves relative to the workpiece gripped by the chuck mechanism 12 under control in each axial direction. That is, the turret body 28 moves from right to left across the bed 6 along the Z-axis (the width direction of the machine body) under drive control of the Z-axis servo motor 26, and further moves along the X-axis and Y-axis combinations in the longitudinal and vertical directions of the machine body under drive control of the X-axis servo motor 29 and the Y-axis servo motor 30. Then, outer diameter machining of the rotating workpiece using a cutting tool and drilling of a phased workpiece using a drill are performed.

[0017] In the second machining, the second workpiece spindle device 4 is driven and controlled by the Z-axis servo motor 20 to move from right to left on the bed 6, and the chuck mechanism 16 receives the workpiece gripped by the chuck mechanism 12 of the first workpiece spindle device 3. At this time, the gripping state of the workpiece is reversed, and backside machining of the workpiece becomes possible in the second machining. The second workpiece spindle device 4, which has gripped the workpiece, is again driven and controlled by the Z-axis servo motor 20 to move from left to right in the machine body width direction and return to its original position. Then, as in the first machining, the turret body 28 is driven and controlled by the Z-axis servo motor 26 to move to the right side of the bed 6, and is also driven and controlled by the X-axis servo motor 29 and the Y-axis servo motor 30 to move in the machine body forward-backward and upward-downward directions. There, the workpiece is subjected to a predetermined machining operation, such as turning.

[0018] In the machine tool 1, the turret tool T performs the second machining on the workpiece as the turret unit 5 approaches the second workpiece spindle unit 4, but at this time, the approach of the turret tool T becomes an issue. Here, approach refers to the distance between the turret tool T and the spindle of the second workpiece spindle unit 4, and by reducing this distance and improving the approach, the turret tool T can be brought closer to the spindle, thereby expanding the machining range of the workpiece. Therefore, in this embodiment, a configuration is adopted that improves the approach of the turret unit 5 to the second workpiece spindle unit 4 when it moves in the X-axis direction.

[0019] Fig. 2 is a perspective view of the internal structure of the machine tool 1 shown in Fig. 1 , showing the second work spindle unit 4 and turret unit 5 assembled in the machining chamber. Fig. 3 is a side view of the second work spindle unit 4 and turret unit 5, seen from inside the machining chamber. The machining chamber 35, where the workpiece is machined, is configured as a closed space surrounded by a cover member to prevent coolant and other liquids sprayed therein from leaking out. The second work spindle unit 4, which moves within the machining chamber 35, is entirely covered by a spindle cover 41, with the chuck portion exposed, and the turret unit 5 has the turret body 28 and other parts, excluding the tool rest 21, covered by a turret cover 42. Note that the cover structure on the side of the first work spindle unit 3 is omitted from Fig. 2 .

[0020] The approach of the turret tool T in the machine tool 1 is a problem of whether the spindle cover 41 and the turret cover 42 can be brought close to each other without interference. Therefore, in this embodiment, as shown in Figure 4, the headstock 14 is configured as a straight type in which, when viewed in the Z-axis direction, the width dimension H in the X-axis direction is approximately constant in the height direction. Here, Figure 4 is a side view showing the second workpiece spindle device 4 and the turret device 5 from inside the machining chamber 35 with the covers shown in Figure 3 removed.

[0021] For example, the headstock 13 of the first workpiece spindle unit 3 has a trapezoidal width to enhance rigidity, and its wider base is fixed to the bed 6 with bolts. The headstock must have high rigidity because it supports the load during workpiece machining. Therefore, ideally, the headstock 14 should also be trapezoidal, as shown by the dashed-dotted line in FIG. 4 , to enhance its rigidity. However, this would increase the width of the headstock 14, including the spindle cover 41, making it difficult to bring the turret body 28 close, resulting in poor accessibility. Therefore, the headstock 14 is designed as a straight type to reduce its width.

[0022] Next, the second workpiece spindle unit 4 is designed so that the structural rigidity of the headstock 14 is increased by increasing the width of the integrally formed spindle table 17 and the spacing between the two guide rails 18 that slidably support the spindle table 17. In this case, if the spindle table 17 is simplified as a doubly supported beam, the wider the spacing between the guide rails 18 that support both ends, the greater the strength required for the spindle table 17. Since slide tables are generally made of cast iron, achieving high strength requires a thick wall, which takes up space for assembling other components. Therefore, the spindle table 17 of this embodiment is made of steel such as S50C, which can ensure sufficient strength while also being thin-walled.

[0023] The machine tool 1 is small and employs a slanted bed 6, so there is not enough space on the assembly surface 60 on which the main machining devices, such as the first workpiece spindle device 3, are mounted. Therefore, to ensure a large gap between the two guide rails 18, 18, the two parallel guide rails 18, 18, 23, 23 for the spindle and the turret are arranged so as to occupy the entire front-to-rear area of ​​the narrow assembly surface 60. Therefore, the gap between the adjacent middle guide rails 18, 23 is extremely narrow. While this is beneficial for the proximity of the turret tool T, it makes it difficult to install the cover member that constitutes the floor of the machining chamber 35.

[0024] 2, the machining chamber 35 forms a closed space including the floor on which the guide rails 18, 23 are located, and the machining equipment and the like are further covered by a spindle cover 41 or the like to provide a seal against coolant. The floor of the machining chamber 35 is configured by a combination of fixed and movable covers because the spindle table 17 and turret table 24 move in the Z-axis direction. Specifically, a first movable cover 51, a second fixed cover 52, a second movable cover 53, and a second fixed cover 54 are arranged from the rear to the front of the machine body, and are configured so that coolant and chips flow down to the front side of the machine body.

[0025] Fig. 5 is a perspective view showing machine tool 1 in a cross section perpendicular to the Z axis. Fig. 6 is a side view showing first and second movable covers 51, 53 and first and second fixed covers 52, 54 in that cross section. First and second fixed covers 52, 54 are fixed to bed 6, and first and second movable covers 51, 53 are configured to move in the Z axis direction within machining chamber 35 integrally with spindle table 17 and turret table 24, respectively.

[0026] The first and second movable covers 51, 53 and the first and second fixed covers 52, 54, which are each separate members, have their ends overlapped one above the other to prevent coolant from leaking from inside the machining chamber 35 and reaching the back side. Specifically, the first overlapping portion 61 is overlapped flatly with the lower end of the rear cover 55 standing at the back of the machining chamber 35 so that the upper end of the bent first movable cover 51 is located on the back side.

[0027] In the portion forming the inclined floor surface, the second overlapping portion 62 between the first movable cover 51 and the first fixed cover 52, the third overlapping portion 63 between the first fixed cover 52 and the second movable cover 53, and the fourth overlapping portion 62 between the second movable cover 53 and the second fixed cover 54 are configured in the same shape. That is, as shown in the enlarged view of the second overlapping portion 62, a downward bent portion 57 is formed at the end of the cover located at the upper rear side, and a wound portion 58 is formed at the end of the cover located at the lower front side, which is wound upward, and is arranged so that the wound portion 58 wraps around from below the bent portion 57 to the back side. In this way, in the first to fourth overlapping portions 61, 62, 63, and 64, the coolant sprayed into the machining chamber 35 flows down to the bottom without entering the back side.

[0028] Incidentally, the machine tool 1 is designed with a wide gap between the guide rails 18, 18 despite the narrow assembly surface 60, so the space available for arranging the first and second fixed covers 52, 54 located on both sides thereof is reduced, making it impossible to obtain the required width dimension. Therefore, in this embodiment, the first and second fixed covers 52, 54 are attached so as to overlap with the spindle table 17. As shown in Figure 6, first and second brackets 67, 68 are fixed to the bed 6 on the outsides of the guide rails 18, 18, and the first and second fixed covers 52, 54 are attached to the upright ends of the brackets.

[0029] In particular, the distance between the guide rails 18, 23 located in the middle section is narrow, leaving only a small gap between the adjacent spindle table 17 and turret table 24. The first bracket 67 is fixed so as to pass through that small gap, and the first fixed cover 52 is attached to it. Therefore, there is no space to attach the first fixed cover 52, which would normally be present, and in this embodiment, the first fixed cover 52 is provided so as to cover the end of the spindle table 17. Furthermore, because the second bracket 68 is fixed to the front end of the bed 6 so as to be located near the guide rail 18, there is also no sufficient space to attach the second fixed cover 54 attached to the second bracket 68, so the second fixed cover 54 is provided so as to cover the end of the spindle table 17. Therefore, in the machine tool 1, the second movable cover 53 and the first and second fixed covers 52, 54 are assembled on the spindle table 17, which is designed to be wide.

[0030] Therefore, in this embodiment, the headstock 14 has a straight width, allowing the spindle cover 41 and the turret cover 42 to approach each other without interference, improving the proximity of the turret tool T. Even though the headstock 14 is straight, the width of the spindle table 17 and the spacing between the two guide rails 18 are designed to be large, thereby enhancing the structural rigidity of the second workpiece spindle device 4. Furthermore, because the spindle table 17 is made of steel such as S50C, strength can be ensured even with a thin wall. Furthermore, by assembling the first and second fixed covers 52, 54 with the second movable cover 53 so that they cover the spindle table 17, it is possible to provide a wide spacing between the guide rails 18, 18 even with a narrow assembly surface 60.

[0031] Although one embodiment of the present invention has been described, the present invention is not limited to this embodiment, and various modifications are possible without departing from the spirit of the present invention.

[0032] REFERENCE SIGNS LIST 1...machine tool 3...first workpiece spindle device 4...second workpiece spindle device 5...turret device 6...bed 13, 14...headstock 17...spindle table 18, 23...guide rail 24...turret table 35...machining chamber 51...first movable cover 52...first fixed cover 53...second movable cover 54...second fixed cover 60...assembly surface T...turret tool

Claims

1. A machine tool comprising: a slanted bed with a forward-inclined upper surface as an installation surface for the equipment; a first work spindle device fixed to the installation surface of the bed and with the center line of the spindle set in the width direction of the machine body; a second work spindle device disposed opposite the first work spindle device in the width direction of the machine body on the installation surface of the bed and assembled so as to be movable in the width direction of the machine body; and a turret device disposed behind the second work spindle device on the installation surface of the bed and assembled so as to be movable in the width direction of the machine body and in a direction along the slant of the installation surface, wherein the second work spindle device is a straight type in which the width dimension of a headstock which rotatably supports a spindle is approximately constant in the height direction.

2. The machine tool according to claim 1, wherein the turret device has a turret table carrying a tool rest that slides on two guide rails in the width direction of the machine provided on the mounting surface of the bed, and the second work spindle device has a spindle table carrying the headstock that slides on two guide rails in the width direction of the machine provided on the mounting surface of the bed, and the two guide rails for the spindle and the turret, which are arranged in parallel, are arranged to occupy the entire fore-aft direction of the mounting surface.

3. A machine tool according to claim 2, wherein said spindle table is made of steel.

4. A machining chamber surrounded by cover members in which workpiece machining is carried out is configured with cover members which cover the guide rails for the spindle and turret and form the floor of the machining chamber, the cover members being composed of a first movable cover integral with the turret table, a second movable cover integral with the spindle table, a first fixed cover located between the first movable cover and the second movable cover, and a second fixed cover located on the front side of the machine body relative to the second movable cover, the first fixed cover being positioned so as to cover the spindle table via a first bracket fixed to the assembly surface between adjacent guide rails of the turret device and the second workpiece spindle device. A machine tool as described in claim 2 or claim 3.

5. A machine tool according to claim 4, wherein said second fixed cover is disposed so as to cover said spindle table via a second bracket fixed to the front end of said bed.

Images