Machine tool

Abstract

In order to enable suitable addressing of the diversification of user needs, this machine tool having two main shaft devices disposed facing one another comprises: a first main shaft device which rotates a workpiece gripped by a first chuck mechanism; a second main shaft device which is disposed facing the first main shaft device in the machine body width direction and rotates a workpiece gripped by a second chuck mechanism; and a turret device which is disposed so as to overlap with the second main shaft device in the machine body front-rear direction and uses a movement mechanism to move a tool attached to the turret main body with respect to the workpiece held by the first chuck mechanism or the second chuck mechanism. The turret main body comprises a tool holder to which a plurality of tools for machining the workpiece are attached with the blade edges thereof toward the first main shaft device side and the second main shaft device side, a fixing part which is integrated with the movement mechanism, and an adjustment part which can be exchanged between the tool holder and the fixing part.

Description

machine tool

[0001] The present invention relates to a machine tool having two spindle units arranged opposite each other and a turret unit equipped with tools for workpieces held by each spindle unit.

[0002] Patent Document 1 describes a twin-opposed spindle lathe equipped with two spindle units for gripping a workpiece. In such a machine tool, a turret body to which a tool is fixed uses a movement mechanism to move the tool relative to a workpiece gripped by one of the spindle units. This allows the machine tool to perform continuous machining on the same workpiece by machining a workpiece with one spindle unit and then gripping and machining the workpiece with the other spindle unit.

[0003] Japanese Patent Application Publication No. 1-289603

[0004] In the machine tool described above, a turret unit is provided on each of the pair of spindle units, and tools for machining workpieces are attached to the tool rests with their cutting edges facing the respective spindle units. Moreover, because the cutting edges of the tools are attached to the respective turret units, there is a risk of interference during operation of the machine tool. Therefore, to avoid this interference, the maximum length of the tools is limited, which places constraints on machining applications. On the other hand, if the goal is to ensure the maximum length of the tools, the dimensions of the corresponding parts will be long, and depending on the hardness of the workpiece and the machining conditions, the rigidity of the turret body cannot be ensured, which could result in adverse effects such as vibration during machining.

[0005] In order to solve the above problem, an object of the present invention is to provide a machine tool having two spindle units arranged opposite each other, which can suitably respond to the diversifying usage needs of users.

[0006] In one aspect of the present invention, a machine tool comprises a first spindle unit that rotates a workpiece gripped by a first chuck mechanism, a second spindle unit that is arranged opposite the first spindle unit in the width direction of the machine body and that rotates a workpiece gripped by a second chuck mechanism, and a turret unit that is arranged so as to overlap the second spindle unit in the front-to-rear direction of the machine body and that moves tools attached to a turret body relative to the workpiece gripped by the first chuck mechanism or the second chuck mechanism using a movement mechanism, and the turret body comprises a tool post on which a plurality of tools for machining the workpiece are attached with their cutting edges facing toward the first spindle unit and the second spindle unit, a fixed unit assembled to the movement mechanism, and an adjustment unit that is interchangeable between the tool post and the fixed unit.

[0007] According to the machine tool having the above configuration, the turret body can have its cutting edge facing the first and second spindle units, respectively, and multiple tools can be attached to the tool rest. Furthermore, the adjustment unit between the fixed unit and the tool rest, which is attached to the moving mechanism, is replaceable. Therefore, by replacing the adjustment unit with one of a different length, the distance from the tool rest to the fixed unit can be changed, and when machining using the second spindle unit, tools of the desired length can be attached regardless of the tool length. In addition, the adjustment unit can be replaced with one of an optimal length depending on the application, for example, to ensure the rigidity of the turret body. As a result, the machine tool can be effectively adapted to the diverse needs of users of the machine tool.

[0008] It is an external perspective view showing one embodiment of a machine tool. It is an enlarged perspective view showing a turret body. It is a diagram for explaining the distance from the tool rest to a fixed part. It is a sectional view of the turret body. It is an enlarged perspective view showing the turret body after replacing the adjustment part.

[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, showing the internal structure of the machine body. The machine tool 1 of this embodiment is an NC lathe, and various machining devices for machining a workpiece are assembled on a bed 6. The machine tool 1 is a two-spindle opposed lathe configured with a slant-type bed that is inclined so that the front side is lower, and is provided with, as machining devices for machining the workpiece, a first spindle unit 3 that rotatably grips the workpiece, a second spindle unit 4 disposed opposite the first spindle unit 3, and a turret unit 5 to which a plurality of tools are attached.

[0010] The first spindle unit 3 is designed to be horizontal with its spindle aligned in the width direction of the machine body, and the second spindle unit 4 is arranged coaxially with the first spindle unit 3. In this embodiment, the direction parallel to the spindles of the first and second spindle units 3, 4 is described as the Z-axis. In this embodiment, the second spindle unit 4, which is coaxial with the first spindle unit 3, is mounted on the bed 6 so as to move in the left-right direction of the machine body along the Z-axis.

[0011] The first spindle unit 3 has a spindle, which is rotatably mounted on a cylindrical headstock 11, and a chuck mechanism 12, which grips and releases a workpiece, is attached to it so that it can rotate around the spindle. The chuck mechanism 12 grips and releases the workpiece by opening and closing chuck jaws via the extension and contraction of a cylinder. The spindle is configured so that the rotation shaft of a motor is transmitted to the spindle, allowing the phasing of the workpiece gripped by the chuck mechanism 12 during machining and rotation around the spindle at a predetermined speed. The first spindle unit 3 has the headstock 11 integrated with a pedestal 13, which is firmly fixed to the left side of the bed 6 with bolts.

[0012] Like the first spindle device 3, the second spindle device 4 has a rotatable spindle mounted on a headstock 15, on which a coaxial chuck mechanism 16 is mounted opposite the chuck mechanism 12. Like the chuck mechanism 12, the chuck mechanism 16 grips and releases a workpiece by opening and closing chuck jaws via the extension and contraction of a cylinder. The spindle is configured so that the rotation shaft of a motor is transmitted, and the workpiece gripped by the chuck mechanism 16 is allowed to be phased during machining and to rotate about the spindle at a predetermined speed.

[0013] The second spindle unit 4 is mounted on a spindle slide 14 and is configured to move in the Z-axis direction on the front inclined surface of the bed 6. Two guide rails 18 parallel to the Z-axis are fixed to the front inclined surface of the bed 6, and a guide block fixed to the underside of the spindle slide 14 is slidably engaged with them. The second spindle unit 4 is capable of moving in the direction of extension of the Z-axis by a ball screw mechanism, and 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 spindle slide 14, and the rotation output of the Z-axis servo motor 20 causes the spindle slide 14 to move linearly in the Z-axis direction.

[0014] The turret device 5 is disposed behind the second spindle device 4 and includes a turret body 51 to which a tool T is fixed, and a movement mechanism 52 that moves the turret body 51 in the Z-axis direction and in a direction perpendicular to the Z-axis. The turret device 5 is configured so that the movement mechanism 52 moves a tool post 40 (described later) of the turret body 51 in the Z-axis direction and in the Y-axis direction and the X-axis direction perpendicular to the Z-axis.

[0015] 2 is an enlarged view of the turret body 51. The turret body 51 has a tool rest 40, a fixing portion 41, and an adjustment portion 42. The tool rest 40 is, for example, a regular dodecagon, and a tool T can be attached and detached to each side via a tool holder 43. A rotary tool such as an end mill or a drill, or a cutting tool such as a cutting tool, is detachably fixed to the tool holder 43. The tool holder 43 has a threaded portion that threadably engages with a threaded member such as a bolt or a screw. The rotary tool or cutting tool is attached to the tool holder 43 by the threaded member.

[0016] On the tool rest 40, the tool T for machining a workpiece held by the first spindle unit 3 is attached with its cutting edge facing the first spindle unit 3, and the tool T for machining a workpiece held by the second spindle unit 4 is attached with its cutting edge facing the second spindle unit 4. Hereinafter, when distinguishing between the tool T for machining a workpiece held by the first spindle unit 3 and the tool T for machining a workpiece held by the second spindle unit 4, the tool T will be distinguished by adding "1" or "2" to the end of the reference numeral.

[0017] The fixed part 41 is located to the right of the tool post 40, where the second spindle unit 4 is located, when viewed from the front of the machine body, and is fixed to a movement mechanism 52 (more specifically, the turret X-axis slide 27, which will be described later). An indexing servo motor 22 is attached to the fixed part 41. The turret unit 5 is configured so that the tool post 40 rotates by controlling the rotational operation of the indexing servo motor 22, and the tool T to be used for machining can be selected by rotation indexing. In addition, a detachable adjustment part 42 is incorporated into the turret body 51 between the tool post 40 and the fixed part 41. The detailed configuration of the adjustment part 42 will be described later.

[0018] As shown in FIG. 1 , the movement mechanism 52 includes a turret Z-axis slide 24 that slides (moves) the turret body 51 in the Z-axis direction and a turret X-axis slide 27 that moves the turret body 51 in the X-axis direction, which is perpendicular to the Z-axis. The turret Z-axis slide 24 has a guide block on its underside that slidably engages with a guide rail 23 formed on the front inclined surface of the bed 6, enabling it to move in the Z-axis direction. Furthermore, 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 turret Z-axis slide 24. The screw shaft 25 is connected to the rotation shaft of a Z-axis servo motor 26, and the rotation output of the screw shaft 25 causes the turret Z-axis slide 24 to slide in the Z-axis direction. The top surface of the turret Z-axis slide 24 is tilted forward by 45 degrees, the same as the inclination of the bed 6. In this embodiment, this inclination will be described as the X-axis.

[0019] The turret X-axis slide 27 is slidably mounted on an X-axis guide rail formed on the upper surface of the turret Z-axis slide 24. The front surface of the turret X-axis slide 27 is a vertical surface, and in this embodiment, the direction parallel to the vertical surface of the turret X-axis slide 27 is described as the Y-axis. A Y-axis guide rail is formed on the front surface of the turret X-axis slide 27, and a fixed portion 41 of the turret main body 51 is slidably mounted on the Y-axis guide rail. Specifically, a screw shaft (not shown) connected to the X-axis servo motor 29 is supported via a bearing on the turret Z-axis slide 24, 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 the Y-axis servo motor 30 is supported via a bearing on the turret X-axis slide 27, and the screw shaft passes through a nut member fixed to the fixed portion 41. As a result, the rotational outputs of the X-axis servo motor 29 and the Y-axis servo motor 30 allow the turret X-axis slide 27 to move linearly in the X-axis direction and the turret main body 51 to move linearly in the Y-axis direction.

[0020] The machine tool 1 configured as described above is capable of performing a first machining operation on a workpiece held by the first spindle device 3, and a second machining operation on a workpiece held by the second spindle device 4. Specifically, the workpiece is held by the chuck mechanism 12 of the first spindle device 3. The turret device 5 controls the drive of the indexing servo motor 22, and the tool T1 for the first machining operation is swiveled and indexed from the multiple tools T attached to the tool rest 40.

[0021] Next, the turret device 5 controls movement in each axis direction to position the tool T at a machining position relative to the workpiece. That is, the turret body 51 moves from the right side to the left side of the bed 6 by drive control of the Z-axis servo motor 26, and further moves in the longitudinal direction and vertical direction of the machine body by a combination of the X-axis and Y-axis by drive control of the X-axis servo motor 29 and the Y-axis servo motor 30. The positioning of the first machining tool T1, which has been swivel-indexed by such movement, is performed on the workpiece, and external diameter machining and internal diameter machining using a cutting tool, or hole drilling using a drill, etc., is performed.

[0022] Furthermore, in the machine tool 1, after the first machining operation, the second machining operation using the second spindle unit 4 can be performed consecutively. In the second machining operation, the second spindle unit 4 is moved from the right side to the left side of the bed 6 by drive control of the Z-axis servo motor 20. The chuck mechanism 16 of the second spindle unit 4 receives the workpiece gripped by the chuck mechanism 12 of the first spindle unit 3. At this time, the workpiece is turned over, and the back side of the workpiece can be machined by the tool T2 for the second machining operation attached to the tool rest 40. After gripping the workpiece, the second spindle unit 4 is again moved from the left side to the right side in the machine body width direction by drive control of the Z-axis servo motor 20 and returns to its original position.

[0023] Then, to perform the second machining on the workpiece gripped by the second spindle device 4, the tool T2 in the turret device 5 is rotated and indexed and moved to the machining position. As in the first machining described above, the turret body 51 is moved to the right side of the bed 6 by drive control of the Z-axis servo motor 26, and is also moved in the front-to-rear and up-to-down directions of the machine body by drive control of the X-axis servo motor 29 and the Y-axis servo motor 30. There, predetermined machining, such as internal diameter machining, is performed on the workpiece.

[0024] In the machine tool 1 configured as described above, the second spindle unit 4 and the turret body 51 are arranged to overlap in the fore-and-aft direction of the machine body. Therefore, the tool T2 that machines the workpiece held by the chuck mechanism 16 is attached to the tool rest 40 with its cutting edge facing inward toward the fixed portion 41, as shown in Figure 2. However, the tool T2 attached in this manner may interfere with the components that make up the turret body 51 when the machine tool 1 is in operation.

[0025] In the turret body 51 shown in FIG. 3 , the size of the internal space of the tool rest 40, i.e., the distance from the tool holder 43 to which the tool T2 is attached, to the fixed part 41 is L1. To prevent the tool T2 attached to the tool rest 40 from interfering with the fixed part 41, the length of the tool T2 must be at least shorter than L1. As a result, for example, when machining an inner diameter of a workpiece in the second machining, the depth of the inner diameter that can be formed in the second machining may be shallower than the depth of the inner diameter that can be formed in the first machining. This places restrictions on the machining applications that can be performed in the second machining in the machine tool 1, which may make it impossible to meet the diversifying needs of users.

[0026] On the other hand, simply increasing the distance from the tool rest 40 to the fixed part 41 may make it impossible to ensure the rigidity of the turret body 51 depending on the hardness of the workpiece to be machined, and may cause adverse effects such as vibrations on the turret body 51 during machining. Therefore, in the machine tool 1 according to this embodiment, the turret body 51 is configured so that the adjustment part 42, which has a different length depending on the machining application, can be replaced, thereby making it possible to suit the diversifying needs of users.

[0027] Next, the detailed configuration of the turret body 51 will be described with reference to Fig. 4. Fig. 4 is a cross-sectional view showing the inside of the turret body 51. The turret body 51 is configured so that the rotation output of the indexing servo motor 22 is transmitted to the tool post 40, and rotation indexing is performed for the tool post 40 to which a plurality of tools are attached.

[0028] The fixed portion 41 of the turret body 51 accommodates a drive shaft 60 that is rotated by the indexing servo motor 22 and a gear reduction mechanism 62 that transmits the driving force from the indexing servo motor 22 to the drive shaft 60. The drive shaft 60 is held by a bearing inside the fixed portion 41 so that it can rotate about a center line a. The gear reduction mechanism 62 is made up of a small-diameter motor gear attached to the motor shaft of the indexing servo motor 22, a large-diameter drive shaft gear fixed to the drive shaft 60, and a plurality of intermediate gears that mesh with each other between a motor gear 63 and a drive shaft gear 64.

[0029] The adjustment unit 42 is a cylindrical member having openings at a first end 42A fixed to the tool post 40 and a second end 42B fixed to the fixed unit 41. A cylindrical rotation transmission shaft 61 is rotatably held within the adjustment unit 42 via a bearing. With the adjustment unit 42 fixed to the fixed unit 41 at the second end 42B with a bolt, the rotation transmission shaft 61 is fixed coaxially to the drive shaft 60, allowing the rotation transmission shaft 61 and the drive shaft 60 to rotate about the center line a.

[0030] The first end 42A of the adjustment portion 42 has a small-diameter portion whose outer diameter is smaller than that of other portions, and can be press-fitted into the inner hole of the bearing. An opening 40A is formed at the end of the tool post 40 facing the adjustment portion 42, into which the first end 42A of the adjustment portion 42 can be inserted, and the small-diameter portion 44 is inserted into this opening 40A while holding the bearing. In addition, the end of the rotation transmission shaft 61 facing the tool post 40 is coaxially fixed to the tool post 40 with a bolt. This allows the tool post 40 to rotate in accordance with the rotation of the adjustment portion 42, and is held rotatably relative to the adjustment portion 42.

[0031] When rotation is output by drive control of the indexing servo motor 22, a reduced rotation is imparted to the drive shaft 60 via a series of meshing gears. Then, the rotation transmission shaft 61 rotates in response to the rotation of the drive shaft 60, and a predetermined angle of rotation is imparted to the tool post 40, which is rotatably held relative to the adjustment unit 42, and one of the multiple tools T attached to the tool post 40 is turned and indexed to be used for machining.

[0032] Furthermore, by replacing the adjustment portion 42 of the turret body 51 with one of a different length, it becomes possible to adjust the length from the tool post 40 to the fixed portion 41, which is the internal space of the tool post 40. Figure 5 is a diagram showing a case in which the adjustment portion 42 of the turret body 51 shown in Figure 2, in which the length from the first end 42A to the second end 42B is a first length, is replaced with an adjustment portion 42 having a second length that is shorter than the first length. The adjustment portion 42 of the turret body 51 shown in Figure 5 has the same configuration as the adjustment portion 42 already described using Figure 2, except that the length from the first end 42A to the second end 42B is different.

[0033] When replacing the adjustment unit 42 of the turret body 51, first, the bolts securing the tool rest 40 to the rotation transmission shaft 61 are released, and the tool rest 40 is removed from the rotation transmission shaft 61. Next, the bolts securing the second end 42B of the adjustment unit 42 to the fixed portion 41 are released, and the adjustment unit 42 is removed together with the rotation transmission shaft 61 from the fixed portion 41. Then, as shown in FIG. 5 , an adjustment unit 42 of a different length is secured to the fixed portion 41 at the second end 42B with a bolt. Then, the first end 42A of the adjustment unit 42 is pressed into the bearing and inserted into the opening 41A of the tool rest 40, and the tool rest 40 is positioned relative to the adjustment unit 42. Finally, the tool rest 40 is secured to the rotation transmission shaft 61 with a bolt.

[0034] According to the machine tool 1 according to the present embodiment described above, in the machine tool 1 in which the first spindle unit 3 and the second spindle unit 4 are arranged opposite each other, the turret body 51 is provided with the adjustment unit 42 that enables adjustment of the distance between the tool post 40 and the fixed unit 41 (the size of the internal space of the tool post 40). As a result, by replacing the adjustment unit 42 in the turret body 51 with one of a different length, it becomes possible to attach a tool T of a length desired by the user to the tool post 40 depending on the application in the second machining. As a result, it is possible to suitably respond to the diversifying needs of users who use the machine tool.

[0035] The adjustment unit 42 rotatably holds the tool post 40 via a bearing at a first end 42A, and is fixed to the fixed unit 41 with a bolt at a second end 42B. This makes it possible to provide a replaceable adjustment unit 42 without interfering with the rotation and indexing of the tool post 40.

[0036] The drive shaft 60 is rotatably housed in the fixed portion 41, and a rotation transmission shaft 61 coaxially connected to the drive shaft 60 is rotatably housed in the adjustment portion 42. The end of the rotation transmission shaft 61 facing the tool post 40 is fixed to the tool post 40 with a bolt, and the adjustment portion 42 rotatably holds the tool post 40 at its first end 42A by the rotation transmission shaft 61 via a bearing. This makes it possible to provide a replaceable adjustment portion 42 while enabling the power from the indexing servo motor 22 to be smoothly transmitted to the tool post 40 by the drive shaft 60 and the rotation transmission shaft 61.

[0037] Although one embodiment of the present invention has been described, the present invention is not limited to this, and various modifications are possible without departing from the spirit of the present invention. In the above embodiment, the turret body 50 is disposed on the right side when viewed from the front of the machine tool 1, i.e., above the second spindle unit 4. Alternatively, the turret body 50 may be disposed on the left side when viewed from the front of the machine tool 1.

[0038] REFERENCE SIGNS LIST 1 machine tool 3 first spindle device 4 second spindle device 5 turret device 51 turret body 52 moving mechanism 40 tool rest 41 fixed portion 42 adjustment portion

Claims

1. A machine tool comprising: a first spindle unit that rotates a workpiece gripped by a first chuck mechanism; a second spindle unit that is arranged opposite the first spindle unit in the width direction of the machine body and rotates a workpiece gripped by a second chuck mechanism; and a turret unit that is arranged to overlap the second spindle unit in the front-to-rear direction of the machine body and moves tools attached to a turret body using a moving mechanism relative to a workpiece gripped by the first chuck mechanism or the second chuck mechanism, wherein the turret body comprises: a tool post to which a plurality of tools for machining a workpiece are attached with their cutting edges facing toward the first spindle unit and the second spindle unit; a fixed unit assembled to the moving mechanism; and an adjustment unit that is interchangeable between the tool post and the fixed unit.

2. A machine tool as set forth in claim 1, wherein said turret body is provided with a plurality of adjustment sections of different lengths for adjusting the distance from said tool rest to said fixed section.

3. A machine tool as claimed in claim 1 or claim 2, wherein the turret body has a rotation transmission mechanism housed in the fixed section which transmits the rotation of the motor to a drive shaft, a rotation transmission shaft which can be connected to the drive shaft rotatably housed in the adjustment section, and the tool rest is connected to the rotation transmission shaft.

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