Machine tool

Abstract

Provided is a machine tool including: a machine body cover covering various machining devices that perform machining of workpieces; an opening which is formed in the front face of the machine body cover and which connects to a machining chamber where workpiece machining is performed by the machining devices; and a slide structure allowing a slide door that closes the opening to move in both the left and right directions of the opening in the front face of the machine body. For example, the slide structure moves the slide door in both the left and right directions at the front face of the machine body cover while displacing the slide door in the machine body front-back direction at the position to close the opening, and includes a rail structure that supports and moves the slide door in a straight line in both the left and right directions of the machine body and a front-back displacement structure that displaces the slide door in the machine body front-back direction.

Description

machine tool

[0001] The present invention relates to a machine tool in which an opening formed in the front surface of a machine body cover is closed by a single sliding door, and the sliding door can be opened by sliding it in both directions from the opening to the left and right.

[0002] Machine tools such as lathes have a closed space called a machining chamber where workpieces are machined using tools, and the entire machine is covered with a machine cover. For example, in the case of a lathe, the machining chamber contains a spindle device that grips the workpiece and a turret device with multiple tools attached to a tool rest, and workers must access these devices to remove workpieces, change tools, and check the operation of each device. For this reason, machine tools have a machining chamber opening formed on the front of the machine cover, and by opening and closing a front door that closes this opening, workpieces can be machined inside the sealed machining chamber and workers can access each device.

[0003] In a first conventional machine tool described in Patent Document 1 below, horizontal guide rails are formed above and below the front of the machine body cover, and a single sliding door is attached as a front door so that it can be opened and closed. A step is formed in the guide rail at the boundary between the machining chamber cover and the drive mechanism cover, and the sliding door is slidably attached to this step. When the sliding door is closed, its inner surface is in close contact with the opening frame, preventing coolant, which is discharged in large quantities onto the workpiece or tool being cut, from leaking out of the machining chamber. When the opening is opened, the sliding door is lifted outward by the step in the guide rail, allowing it to move.

[0004] JP 5-138491 A JP 2014-73553 A

[0005] The machine tool of the first conventional example described above opens and closes by moving its sliding door to one side (to the left as seen by an operator standing in front of the machine body), but depending on the configuration of the devices in the machining chamber, it may be preferable to be able to open and close the sliding door in both directions. In this regard, the machine tool of the second conventional example described in Patent Document 2 below is a front-facing two-spindle lathe in which a spindle and a tool rest are mounted on two beds, one on the left and one on the right, and two sliding doors provided corresponding to each machining chamber are configured to open in both directions. Note that this machine tool has long rail members fixed to the left and right below an opening in the front of the machine body, and a pair of left and right sliding doors that can move along the rail members.

[0006] However, the second conventional example has a two-door structure with two sliding doors on the left and right, compared to the first conventional example, which had only one sliding door. Therefore, the configuration in which the left and right sliding doors are butted together requires high sealing performance in the center, but it is difficult to ensure sufficient airtightness, and there is a risk that the large amount of coolant discharged during workpiece machining will leak out of the machining chamber. Furthermore, because the sliding doors are opened and closed dozens of times a day, the deterioration of the sealing material in the center will progress quickly, potentially resulting in problems with sealing performance.

[0007] SUMMARY OF THE INVENTION In order to solve the above problems, an object of the present invention is to provide a machine tool equipped with a single front door that can slide both left and right.

[0008] In one aspect of the present invention, a machine tool has a body cover that covers various processing devices that perform workpiece processing, an opening formed on the front of the body cover that communicates with a processing chamber where workpiece processing is performed by the processing devices, and a sliding structure that allows a sliding door that covers the opening to be moved in both directions to the left and right of the opening on the front of the body.

[0009] According to the above configuration, the sliding door provided on the front of the machine body can be opened in both the left and right directions, which improves workability for devices located in the processing chamber on the opposite side from the direction in which the sliding door is opened.

[0010] 9 is a perspective view of an internal structure of a machine body showing an embodiment of a machine tool. FIG. 10 is an external perspective view of an embodiment of a machine tool. FIG. 11 is an external perspective view of an embodiment of a machine tool with the sliding door open. FIG. 12 is a perspective view of a machine body cover showing an upper sliding structure and a lower sliding structure of the sliding door. FIG. 13 is a cross-sectional view of the upper sliding structure of the sliding door as seen in the direction of movement. FIG. 14 is a cross-sectional view of the lower sliding structure of the sliding door as seen in the direction of movement. FIG. 15 is a plan view of the upper sliding structure within the area surrounded by part C in FIG. 4. FIG. 16 is a plan view of the lower sliding structure within the area surrounded by part D in FIG. 15. FIG. 17 is a partial cross-sectional view of the handle of the sliding door. FIG. 18 is a cross-section taken along the arrows E-E in FIG. 9, showing a switch on the handle.

[0011] 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 an opposed twin-spindle 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 workpiece spindle unit 3 that rotatably grips the workpiece, a second workpiece spindle unit 4 disposed opposite the first workpiece spindle unit 3, and a turret unit 5 having a plurality of tools.

[0012] The first work spindle device 3 is designed so that its center line is in the width direction of the machine body and is horizontal, while the second work spindle device 4 and the first work spindle device 3 have their spindles arranged coaxially. In this embodiment, the direction parallel to the spindle of the first work spindle device 3 (the width direction of the bed 6) will be described as the Z axis. In this embodiment, the second work spindle device 4, which is coaxial with the first work spindle device 3, is assembled on the bed 6 so as to move in the left-right direction parallel to the Z axis. Note that "left-right" in this embodiment refers to the width direction of the machine body as viewed from the front of the machine body.

[0013] The first workpiece spindle device 3 has a spindle rotatably mounted on a cylindrical headstock 11, to which is attached a chuck mechanism 12 for gripping and releasing a workpiece. 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 chuck mechanism 12 to determine the phase during machining of the gripped workpiece and to rotate it at a predetermined speed. The first workpiece spindle device 3 has the headstock 11 integrated with a pedestal 13, which is firmly fixed to the left side of the bed 6 with bolts.

[0014] Like the first workpiece spindle device 3, the second workpiece 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 the workpiece by opening and closing the chuck jaws through 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 at a predetermined speed.

[0015] The second workpiece spindle device 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 workpiece spindle device 4 is movable in the Z-axis direction 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.

[0016] Next, a turret device 5 is disposed behind the second workpiece spindle device 4, and its tool rest 21 is configured to move in the Z-axis direction and in the Y-axis and X-axis directions perpendicular to the Z-axis. Furthermore, in the turret device 4, a plurality of tools T are attached to the disk-shaped tool rest 21 at equal intervals in the circumferential direction, so that the tool T to be used for machining can be selected by rotation indexing. A guide rail 23 is provided on the front inclined surface of the bed 6 of the turret device 5, and a guide block fixed to the underside of a turret Z-axis slide 24 slidably engages with the guide rail 23, enabling movement in the Z-axis direction by a ball screw mechanism.

[0017] 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 rotating shaft of a Z axis servo motor 26 is connected to the screw shaft 25, and the turret Z axis slide 24 is configured to move linearly in the Z axis direction by the rotation output of the motor. The upper surface of the turret Z axis slide 24 is inclined forward at 45 degrees, the same as the inclination of the bed 6, and in this embodiment, this inclination will be described as the X axis.

[0018] A turret X-axis slide 27 is attached to the turret Z-axis slide 24 so as to slide 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 this vertical surface will be described as the Y-axis. Therefore, a Y-axis guide rail is formed on the front surface of the turret X-axis slide 27, and a turret main body 28 comprising the tool post 21, indexing servo motor 22, etc. is attached to slide on the Y-axis guide rail.

[0019] A screw shaft (not shown) connected to an 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 a 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 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.

[0020] The machine tool 1 configured as described above is capable of first machining of a workpiece held by the first workpiece spindle device 3, and second machining of a workpiece held by the second workpiece spindle device 4. Specifically, a workpiece is held by the chuck mechanism 12 of the first workpiece spindle device 3, and predetermined machining is performed on the workpiece by the turret device 5. The turret device 5 controls the drive of an indexing servo motor 22, and a predetermined tool T to perform machining is swiveled and indexed from a plurality of tools T attached to the tool rest 21.

[0021] 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 28 moves from the right side to the left side of the bed 6 in the Z-axis, which is the width direction of the machine body, by drive control of the Z-axis servo motor 26, and further moves 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 in combination with the X-axis and Y-axis. The tool T, which has been swiveled and indexed, is positioned by such movement, and the workpiece is subjected to external machining using a cutting tool or hole drilling using a drill.

[0022] Furthermore, in the machine tool 1, a second machining operation is performed using the second workpiece spindle device 4. In the second machining operation, the second workpiece spindle device 4 is moved from the left side to the right side of the bed 6 along the Z axis, which is the width direction of the machine body, by drive control of the Z-axis servo motor 20. The chuck mechanism 16 of the second workpiece spindle device 4 receives the workpiece held by the chuck mechanism 12 of the first workpiece spindle device 3. At this time, the workpiece is turned over, making it possible to perform back machining on the workpiece by the second machining operation. Having gripped the workpiece, the second workpiece spindle device 4 is again moved from the left side to the right side along the width direction of the machine body 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 workpiece spindle device 4, the tool T 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 28 is moved to the right side of the bed 6 by drive control of the Z-axis servo motor 26, and is 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 cutting machining, such as internal diameter machining, is performed on the workpiece.

[0024] While the machine tool 1 performs the above-described automatic workpiece machining, an operator also performs other tasks inside the machine by opening the front door. These tasks include the attachment and detachment of workpieces to the first and second workpiece spindle units 3 and 4, as well as the replacement of tools T in the turret unit 5. For these tasks, an operator standing outside the machine body must be able to easily reach each device without being obstructed by an open door. In this regard, the machine tool 1 preferably has a single sliding door that can be opened in both directions, rather than sliding doors on both sides as in the second conventional example. Therefore, FIG. 2 is an external perspective view of the machine tool 1 equipped with a sliding door, and FIG. 3 is an external perspective view showing the sliding door in an open state.

[0025] In machine tool 1, the various processing devices shown in Fig. 1 are covered by a machine body cover 7, and a processing chamber 10 can be opened and closed by a sliding door 8 provided in an opening 70 on the front. Within processing chamber 10, a chuck mechanism 12 for first work spindle device 3 is located on the left side, and a chuck mechanism 16 for second work spindle device 4 and a tool rest 21 for turret device 5 are located on the right side. The sliding door 8 in this embodiment can slide in both left and right directions from opening 70, and can be opened to the right as shown by the solid line in Fig. 3, or to the left as shown by the dashed dotted line.

[0026] The front surface of the machine cover 7, including the sliding door 8, is formed so that a vertical flat portion rising from the bottom edge is connected to a curved portion that curves from the flat portion to the top edge toward the rear of the machine. Therefore, the top and bottom edges of the sliding door 8 do not overlap vertically, and therefore sliding structures are provided at the top and bottom edges to ensure stable opening and closing. Figure 4 is a perspective view of the machine cover 7, showing the upper and lower sliding structures 31 and 32 of the sliding door 8. Figure 5 is a cross-sectional view of the upper sliding structure 31 as seen in the direction of movement of the sliding door 8 (cross-section taken along arrows A-A in Figure 6 , which will be described later), and Figure 6 is a cross-sectional view of the lower sliding structure 32 as seen in the direction of movement of the sliding door 8 (cross-section taken along arrows B-B in Figure 7 , which will be described later).

[0027] A linear guide is used in the upper sliding structure 31, and a guide rail 41 is fixed to a support plate 43 attached to the machine frame side that supports the machine cover 7. A guide block 42 is fixed to a bracket 44 connected to the sliding door 8 side, and a rail structure is provided in which the guide block 42 slidably engages with the guide rail 41. On the other hand, the lower sliding structure 32 is provided with a rail 45 fixed to a support base 47 attached to the machine frame side, and a rail structure in which grooved wheels 46 journaled on the sliding door 8 side roll on the rail 45.

[0028] The upper and lower sliding structures 31, 32 are also provided with a longitudinal displacement structure that displaces the sliding door 8, which moves in both left and right directions on the front surface of the machine body cover 7, in the longitudinal direction of the machine body. This is because the gaskets 48 of the sliding door 8 need to move over the gaskets 49 on the machine body cover 7 side. As shown in Figures 5 and 6, strip-shaped gaskets 48 are provided continuously in the vertical direction on the back surface of both the left and right sides of the sliding door 8, and similar strip-shaped gaskets 49 are also provided on the machine body cover 7 side at positions indicated by dashed dotted lines corresponding to both left and right sides of the opening 70. These gaskets 48, 49 overlap on both left and right sides of the opening 70 in the left and right direction of the machine body, thereby sealing the processing chamber 10.

[0029] Therefore, to improve the sealing performance of the machining chamber 10, it is desirable for the overlap width H of the packings 48, 49 to be wide. However, in a machine tool 1 in which the sliding door 8 moves in both left and right directions, the packings 48, 49 come into contact with each other when opening and closing, creating resistance. Furthermore, interference between the packings 48, 49 can damage the sealing structure and accelerate deterioration. Therefore, the upper and lower sliding structures 31, 32 are provided with a forward / backward displacement structure that displaces the sliding door 8 in the forward / backward direction of the machine body to prevent interference between the packings 48, 49. Specifically, the sliding door 8 moves away from the machine body cover 7 when opening and closing, but moves closer to the machine body cover 7 when closing the opening 70.

[0030] Therefore, in the upper sliding structure 31, a shaft 51 is fixed to the bracket 44, and the shaft 51 is slidably inserted into a shaft guide (bush) 52 fixed to the sliding door 8. In addition, in the lower sliding structure 32, a shaft 53 is fixed to the sliding door 8, and is slidably inserted into a shaft guide (bush) 54 fixed to the machine frame. As shown in Figure 4, the shaft guides 52, 54 etc. are provided on the top and bottom and both the left and right sides of the sliding door 8, and the shafts 51, 53 are provided so that their center lines are parallel in the fore-and-aft direction of the machine body.

[0031] Here, Figure 7 is a plan view showing the upper sliding structure 31 in the area enclosed by part C in Figure 4, and Figure 8 is a plan view showing the lower sliding structure 32 in the area enclosed by part D in Figure 4, with the bottom of both figures being the front of the aircraft. As shown in these figures, the forward / backward displacement structure further has guide surfaces 55, 56 formed by a strip-shaped plate fixed to the aircraft frame so as to stand upright. These guide surfaces 55, 56 are arranged parallel to the guide rails 41 and 45. Cam followers 57, 58 are supported by vertical shafts on the sliding door 8 side and are abutted against the guide surfaces 55, 56 from the front of the aircraft, so as to roll as the sliding door 8 moves in both the left and right directions.

[0032] The guide surfaces 55, 56 are formed with guide portions that align with the positions of the cam followers 57, 58 when the sliding door 8 closes the opening 70. At the guide portions, the guide surfaces 55, 56 are separated from each other, and at their ends, bent portions 551, 561 that bend toward the rear of the machine body (upper side in the drawing) are formed symmetrically across a gap. Therefore, the guide surfaces 55, 56, which are continuous in the left-right direction of the machine body, allow the rolling cam followers 57, 58 to displace toward the rear of the machine body at the guide portions. Therefore, guide blocks 61, 62 are provided at positions corresponding to the guide portions to guide the cam followers 57, 58 toward the rear of the machine body along the bent portions 551, 561.

[0033] The guide blocks 61, 62 have mountain-shaped guide surfaces formed to follow the bent portions 551, 561 of the guide surfaces 55, 56, and the cam followers 57, 58 roll on these guide surfaces. Such structures for displacing the sliding door 8 back and forth using the guide blocks 61, 62 are provided on both the left and right sides of the sliding door 8 and the opening 70. As shown in Figures 7 and 8, the sliding door 8 is closed when the cam followers 57, 58 are positioned in the center of the guide blocks 61, 62 (displaced toward the rear of the machine body). Furthermore, a positioning mechanism is provided on the upper sliding structure 31 side to stabilize this closed state.

[0034] As shown in Figure 7, the positioning mechanism has a positioning plate 63 fixed to the upper end of the sliding door 8, and a restraining means for restraining the movement of the positioning plate 63 is provided on the machine frame side. The positioning plate 63 protrudes horizontally toward the rear of the machine body, and its rear end is M-shaped. The restraining means has one end of a swing bar 65 pivotally supported by a swingable shaft, the other end of which is supported by a cam follower 66, the other end of which is supported so as to be biased toward the positioning plate 63 by a spring 67. Therefore, when the sliding door 8 is closed, the cam follower 66 abuts against the M-shaped portion of the positioning plate 63 and moves relatively, climbing over either the left or right peak and fitting into the valley as shown.

[0035] The sliding door 8 of the machine tool 1 is composed of a single door, which makes it heavier than the sliding door 8 composed of two doors as in the second conventional example. Therefore, in this embodiment, an auxiliary system is provided to assist the operator in opening and closing the door. The auxiliary system, which is provided on the machine frame, has an air motor 68 fixed as a rotation drive device in the position shown in FIG. 4 , and a pulley 72 journaled on the opposite side of the air motor 68. A timing belt 73, which connects both ends of the sliding door 8 to form a loop, is stretched between pulleys 71 and 72, which are fixed to the rotation shaft of the air motor 68. Thus, in this auxiliary system, the rotational output of the air motor 68 in a predetermined direction is transmitted via the timing belt 73 as a force pulling the sliding door 8 to either the left or right.

[0036] Next, the auxiliary system has a switch for operating the air motor 68 provided on the handle of the sliding door 8. The sliding door 8 has a pair of handles 75 provided at symmetrical positions on either side of the central window to make it easier for the operator to open it in both directions. Figure 9 is a partial cross-sectional view showing the handle 75 of the sliding door 8. The handle 75 has two support parts 752, one above and one below, that are perpendicular to a vertical grip part 751, and the same structure is provided for tilting the handle 75 left and right relative to the support parts 752 located above and below.

[0037] A protrusion 80 is formed on the surface of the sliding door 8, and a support portion 752 fits into a hole drilled in the protrusion 80 with a gap therebetween. A mounting block 76 is screwed to the tip of the support portion 752 within the protrusion 80, and the mounting block 76 is pivotally supported by a fixed block 78 on the sliding door 8 side via a vertical pin 77. Figure 10 is a cross-section taken along the arrows E-E in Figure 9, showing a switch for the handle 75. The handle 75 tilts a certain angle left or right around the vertical pin 77 when the operator opens or closes the door, and is normally returned to a center position by the biasing force of a spring. The auxiliary system detects the tilt of the handle 75 and controls the supply of air to the air motor 68.

[0038] The air motor 68 has two input ports for outputting clockwise and counterclockwise rotation, and the auxiliary system is configured with an air circuit for supplying air to a predetermined input port depending on the opening or closing direction of the sliding door 8. Furthermore, because the handle 75 tilts in a predetermined direction depending on the opening or closing action of the operator, the auxiliary system uses a pair of limit switches 79 (79R, 79L) that detect the tilt of the support part 752 at that time. The limit switch 79R detects the operator's action when opening the sliding door 8 to the right, and the limit switch 79L detects the operator's action when opening it to the left. Based on the detection signal from these limit switches 79, the auxiliary system controls the switching of valves that make up the air circuit, and air is supplied to the air motor 68 via a predetermined input port.

[0039] Next, the opening and closing operation of the sliding door 8 in the machine tool 1 will be described. For example, when an operator opens the sliding door 8 to the right as shown by the solid line in FIG. 3 , the operator grips the left handle 75 and applies force to the right. The operator's force tilts the grip portion 751 of the handle 75 to the right, pressing the limit switch 79R and activating the assist system. That is, a valve is switched in accordance with a detection signal from the limit switch 79R, and air is supplied to the air motor 68, which outputs rotation in a predetermined direction. The rotation output of the air motor 68 is transmitted to the timing belt 73, which pulls the connected sliding door 8 to the right. Therefore, this output of the air motor 68 assists the operator in opening the sliding door 8. Note that the assist system operates in the same way even when the operator grips the right handle 75 to open the sliding door 8 to the right. Furthermore, whether the sliding door 8 is opened to the left or closed in either the left or right direction, the assist system applies an assist force in the same direction as the operator applies to the handle 75.

[0040] When the sliding door 8 covering the opening 70 is opened by an operator, the cam followers 57, 58 shown in Figures 7 and 8 roll on the slopes from the centers of the guide blocks 61, 62 as the door starts to move. This movement causes the shafts 51, 53 and the shaft guides 52, 54 to slide relatively forward and backward, and the sliding door 8 moves laterally and is displaced away from the machine cover 7 toward the front of the machine. This causes the gasket 48 of the sliding door 8 to climb over the gasket 49 on the machine cover 7 side. Furthermore, the start of movement of the sliding door 8 also causes the positioning plate 63 to move, and the cam follower 66, which had been fitted into the M-shaped recess, disengages against the biasing force of the spring 67.

[0041] When the sliding door 8 moves to the right or left from the opening 70, the guide block 42 slides along the guide rail 41 in the upper sliding structure 31, and the grooved wheel 46 rolls along the rail 45 in the lower sliding structure 32. Also, the cam followers 57, 58 roll along the guide surfaces 55, 56 in each. Then, by moving the sliding door 8 to the right or left of the machine body as shown by the solid line or the dashed dotted line in Figure 3, the opening 70 is opened, and an operator can work in the processing chamber 10.

[0042] When closing the sliding door 8 after work, the auxiliary system similarly assists the operator's action on the handle 75 with the output of the air motor 68. Similarly, in the upper and lower sliding structures 31, 32, the cam followers 57, 58 roll along the guide surfaces 55, 56, and when in the closed position, the cam followers 57, 58 ride up onto the guide blocks 61, 62 and move into the gaps between the bent portions 551, 561. This moves the sliding door 8 closer to the machine cover 7, and the packings 48, 49 overlap in the left-right direction of the machine, creating a sealed state. The cam follower 66 then moves relatively to fit into the valley of the positioning plate 63.

[0043] As described above, according to this embodiment, the sliding door 8 provided on the front of the machine body can be opened in both the left and right directions. This shortens the distance to the devices arranged in the machining chamber 10 on the opposite side to the direction in which the sliding door 8 is opened, improving workability for the operator. That is, if the width of the machining chamber 10 is large relative to the width of the machine tool 1, the sliding door 8 that blocks the opening 70 also becomes large. When the sliding door 8 is opened, it may not be completely removed from the opening 70 and its end may overlap with the machining chamber 10. This increases the distance between the device and the operator working from outside the machine. However, in this embodiment, for example, by moving the sliding door 8 to the right as shown in FIG. 3, the operator can work closer to the first workpiece spindle device 3 (particularly the chuck mechanism 12) (not shown) located on the left side of the machining chamber 10.

[0044] Furthermore, the sliding door 8, which can be opened and closed to the left and right, moves away from the machine cover 7 as the cam followers 57, 58 roll on the guide surfaces 55, 56, allowing for smooth opening and closing movements without resistance from the packings 48, 49. When the sliding door 8 is closed, the sliding door 8 approaches the machine cover 7 under the guidance of the guide blocks 61, 62, improving the sealing performance between the packings 48, 49 provided on the left and right sides of the opening 70. Furthermore, this embodiment is provided with an auxiliary system in which an air motor 68 assists in opening and closing the large sliding door 8, making the opening and closing operations easy even for workers with weak strength.

[0045] Although an embodiment of the present invention has been described, the present invention is not limited thereto, and various modifications are possible without departing from the spirit and scope of the present invention. For example, in the above embodiment, a twin-spindle lathe equipped with first and second workpiece spindle devices 3, 4 was used as an example of the machine tool. However, a machine tool with a different configuration, such as the second conventional example, may also be used. Furthermore, in the above embodiment, the air motor 68 is activated by detection of the limit switch 79. However, instead of the limit switches 79R, 79L, an air mechanical valve that opens and closes depending on the tilt of the handle 75 may be provided to control the air supply to the air motor 68. Furthermore, in the above embodiment, the air motor 68 was used as an example of a rotation drive device for the auxiliary system that assists in opening and closing the sliding door 8. However, an electric motor may be used instead.

[0046] DESCRIPTION OF SYMBOLS 1...machine tool 3...first workpiece spindle device 4...second workpiece spindle device 5...turret device 7...machine body cover 8...sliding door 10...machining chamber 31...upper slide structure 32...lower slide structure 51, 53...shaft 52, 54...shaft guide 55, 56...guide surface 57, 58...cam follower 61, 62...guiding block 63...positioning plate 65...oscillating bar 66...cam follower 67...spring 68...air motor 73...timing belt 70...opening 75...handle 79 (79R, 79L)...limit switch

Claims

1. A machine tool having a body cover which covers various processing devices which process workpieces, an opening formed on the front surface of the body cover which communicates with a processing chamber in which workpiece processing is performed by the processing devices, and a sliding structure which enables a sliding door which covers the opening to be moved in both left and right directions on the front surface of the body of the machine.

2. A machine tool as described in claim 1, wherein the sliding structure moves the sliding door in both left and right directions on the front surface of the machine body cover, and displaces the sliding door in the fore-and-aft direction of the machine body when it is in a position to close the opening.

3. A machine tool as described in claim 2, wherein the sliding structure comprises a rail structure which supports the sliding door and moves it linearly in both the left and right directions of the machine body, and a forward / backward displacement structure which displaces the sliding door in the forward / backward direction of the machine body.

4. A machine tool as described in claim 3, wherein the forward / backward displacement structure supports the sliding door so as to be displaceable in the forward / backward direction of the machine body relative to the rail structure, a guide surface parallel to the rails that constitute the rail structure is formed on the machine body cover side, a cam follower that rolls on the guide surface is provided on the sliding door, a guide portion is formed on the guide surface corresponding to the position of the cam follower when the sliding door closes the opening, and a guide block is provided on the machine body cover side at a position corresponding to the guide portion for displacing the cam follower toward the rear of the machine body.

5. A machine tool as claimed in any one of claims 1 to 4, further comprising a motion detection unit provided on the sliding door for detecting the opening and closing action of an operator, and an assistance system for assisting the operator in opening and closing the sliding door based on detection by the motion detection unit.

6. The machine tool according to claim 5, wherein said auxiliary system transmits the rotational output of a rotary drive device to said sliding door by a belt.

7. A machine tool as described in claim 6, wherein the sliding door is formed with a handle that tilts in the direction in which force is applied in response to an operator's opening or closing action, and the auxiliary system operates the rotary drive device in response to a detection signal from a detection switch that detects the tilt of the handle.

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