Machine tool

Abstract

Provided is a machine tool in which a bar material workpiece that is fed to a spindle device is gripped by a spindle chuck and is subjected to specific machining, the machine tool comprising a workpiece box that projects to the front side of a front door that opens and closes a machining chamber, an opening / closing shutter that is configured to be closed by being urged upward by an urging member, at a discharge port formed in the front door, a workpiece moving device that moves a bucket for accepting the workpiece falling from the position of the spindle chuck, between an accepting position at which the workpiece is accepted and a discharging position at which the workpiece is discharged from the discharge port, and an orientation switching mechanism that causes the bucket moving to the discharging position to rock to change the orientation thereof from a workpiece accepting orientation to a discharge orientation blocking the discharge port, wherein the opening / closing shutter is formed with an engaging protuberance that protrudes into the machining chamber so as to hook onto an engagement claw of the bucket that is changing to the discharge orientation, and the engaging protuberance is configured such that the amount of protrusion thereof is reduced by an external force.

Description

machine tools

[0001] The present invention relates to a machine tool that receives a machined workpiece at the position of a spindle chuck and discharges it into a workpiece box provided on a front door.

[0002] Some machine tools are provided with a workpiece moving device for discharging the machined workpiece outside the machine after it has been cut off by a cut-off bit. A conventional example of this is disclosed in Patent Document 1 listed below. The workpiece moving device described in this document is configured such that a rotary actuator rotates an arm, causing a bucket to receive the workpiece that has fallen from the spindle chuck, and then the bucket moves to a discharge port and discharges the machined workpiece from a chute to a recovery section.

[0003] More specifically, a bucket is swingably supported at the tip of the arm, and a cam follower is attached to the bucket. When the arm swings, the bucket moves to the discharge position, and the cam follower engages with the cam member, causing the bucket to swing around a support shaft and block the discharge port. This tilt of the bucket causes the workpieces stored in it to roll from the discharge port to a collection section. The machine tool is also provided with a front door on the front side that opens and closes the machining chamber. The collection section that discharges the workpieces is formed integrally with the front door, and the front door is formed with the discharge port for sending the workpieces to the collection section. The workpiece collection section moves together with the front door, and during turning or other operations using a tool, the front door of the machining chamber is closed and the discharge port is blocked by the bucket.

[0004] Japanese Patent Application Laid-Open No. 2004-114226

[0005] In the conventional machine tool, when receiving a machined workpiece, the bucket moves from a discharge position to a receiving position by rotating the arm. Specifically, the bucket blocks the discharge port formed in the front door, preventing coolant, chips, and other debris from scattering outside the machining area. However, if the bucket presses against the discharge port, it is conceivable that the pressed bucket will create resistance when moving the front door. Therefore, a front door with an integrated collection unit can create resistance that hinders opening and closing, potentially making it difficult for the operator to open and close the door smoothly.

[0006] SUMMARY OF THE INVENTION In order to solve this problem, an object of the present invention is to provide a machine tool in which the front door can be opened and closed smoothly.

[0007] In one aspect of the present invention, a machine tool is one in which a bar material workpiece fed into a spindle device is gripped by a spindle chuck in a machining chamber, and a predetermined machining operation is performed on the rotated workpiece using a tool, and the machine tool comprises a work box protruding from the front side of a front door that opens and closes the machining chamber, an opening and closing shutter configured to close a discharge port formed in the front door that leads from the machining chamber to the work box by being biased upward by a biasing member, a work moving device that moves a bucket that receives the workpiece dropping from the position of the spindle chuck between its receiving position and a discharge position where the workpiece is discharged from the discharge port, and a posture switching mechanism that swings the bucket moving to the discharge position, changing it from a workpiece receiving posture to a discharge posture that blocks the discharge port, and the opening and closing shutter is formed with an engaging protrusion that protrudes into the machining chamber so as to be hooked onto the engaging claws of the bucket as it changes to the discharge position, and the engaging protrusion is configured so that the amount of protrusion is reduced by an external force.

[0008] According to this configuration, after being machined, the workpiece held by the spindle chuck is cut off by a cut-off tool or the like and dropped into the bucket. The workpiece is then moved by the workpiece moving device to the discharge position while still contained in the bucket. The bucket is then swung by the position switching mechanism from a workpiece receiving position to a discharge position that blocks the discharge port. The engaging claws are hooked onto the engaging protrusions, which push the opening / closing shutter down against the biasing force of the biasing member, opening the discharge port. This allows the machined workpiece in the bucket to be discharged into a work box attached to the front door. While the engaging protrusions on the opening / closing shutter could collide with other components when the front door is opened or closed, the design minimizes the amount of protrusion caused by external forces, thereby minimizing the impact.

[0009] FIG. 1 is a front view showing one embodiment of a machine tool. FIG. 2 is a perspective view showing a part of a machining chamber with the front door of the machine tool open. FIG. 3 is a perspective view showing a spindle chuck portion that constitutes a spindle device, viewed from inside the machining chamber. FIG. 4 is a perspective view showing a workpiece discharge mechanism. FIG. 5 is a view showing a state immediately before a bucket reaches a discharge position. FIG. 6 is a perspective view showing an attachment structure of an open / close shutter. FIG. 7 is a view taken along arrows A-A in FIG. 7 showing a retraction mechanism for the open / close shutter. FIG. 8 is a cross-sectional view taken along arrow B in FIG. 4 showing a bucket retraction mechanism. FIG. 9 is a cross-sectional view showing a situation in which a machined workpiece is discharged from a bucket to a work box.

[0010] An embodiment of a machine tool according to the present invention will be described below with reference to the drawings. Fig. 1 is a front view of the machine tool according to this embodiment. The machine tool 1 is a lathe equipped with machining devices such as a spindle device and a turret device, and is particularly connected to a bar feeder 2 so that workpieces, such as bar material, are fed into a machining chamber 10 (see Fig. 2) inside the machine. Therefore, the machine tool 1 has a workpiece insertion section formed on the left side of the machine body when viewed from the front, and the bar feeder 2 is installed so that the workpieces can be fed from there.

[0011] The entire machine tool 1 is covered by a machine body cover 11, and a front door 12 is provided at the top center of the front of the machine, with an input operation device 12 provided to the right of the front door 12. The front door 12 is a sliding door that opens to the left along the front of the machine body when viewed from the front. A lathe is configured inside a machining chamber 10 when the front door 12 is open. Although not specifically shown in its entirety, the lathe incorporates a spindle device that rotatably grips a workpiece, a turret device equipped with tools for performing predetermined machining on the rotating workpiece, and the like.

[0012] 2 is a perspective view showing a portion of the inside of the machining chamber 10 with the front door 12 open, and FIG. 3 is a perspective view showing a spindle chuck portion of the spindle unit from inside the machining chamber 10. The spindle unit is supported for rotation by a spindle chuck 15 protruding from a side surface 101 of the machining chamber 10, which is integrally supported by a spindle provided inside the chamber across the side surface 101. A workpiece W fed from the bar feeder 2 is inserted into the spindle, and as shown in FIG. 3, the tip of the workpiece W protrudes from the spindle chuck 15 by a predetermined length. Note that the machine tool 1 is configured so that the center of rotation of the spindle in the spindle unit is horizontal to the width direction of the machine body. In this embodiment, the direction parallel to the center of rotation is defined as the Z-axis, the fore-and-aft direction of the machine body perpendicular to the Z-axis is defined as the X-axis, and the up-and-down direction of the machine body is defined as the Y-axis.

[0013] A turret device is also disposed on the opposite side of the spindle device within the machining chamber 10. The turret device is configured so that a tool table, on which multiple tools are mounted, can be rotated about a central axis parallel to the Z axis, and a tool for machining the workpiece W held by the spindle chuck 15 is selected by rotational indexing. The turret device is also equipped with a drive unit that enables the tool table to move in the Z axis direction and in a direction parallel to the XY plane perpendicular to the Z axis.

[0014] In the machine tool 1, a predetermined machining operation is performed on the tip portion of the workpiece W delivered from the bar feeder 2. Then, a cut-off tool T1 is selected by the rotational indexing of the turret device, and a machined workpiece W1 of a certain length is cut off from the long workpiece W, which is a bar material. The machine tool 1 discharges the machined workpiece W1 (hereinafter simply referred to as workpiece W1) to the outside of the machining chamber 10, thereby enabling continuous machining of the workpiece W delivered from the bar feeder 2. To discharge the workpiece W1 to the outside of the machining chamber 10, the machine tool 1 is provided with a work box 16 that protrudes from the front side of the front door 12, and a discharge port 30 is formed in the front door 12 to communicate between the inside of the work box 16 and the machining chamber 10. In addition, a work moving device 17 is provided in the machining chamber 10 to feed the cut-off workpiece W1 from the discharge port 30 into the work box 16.

[0015] The workpiece moving device 17 is configured such that a bucket 21 for receiving the workpiece W1 is supported by an L-shaped arm 22, and the arm 22 rotates to transport the workpiece W1 received by the bucket 21 within the processing chamber 10. The range of movement of the bucket 21 is between the receiving position for the workpiece W1 shown in Figure 3 and a discharge position (see Figure 5) where the bucket 21 is placed over the discharge port 30 of the workpiece box 16 formed in the front door 12. Here, Figure 4 is a perspective view showing the workpiece discharge mechanism 17, particularly showing the state in which the bucket 21 has been moved to the discharge position.

[0016] The L-shaped arm 22 has a swivel section 223 that is perpendicular to a horizontal section 221 that is parallel to the Z-axis. A support frame 23 is fixed to the tip of the swivel section 223, and a bucket 21 is attached to the support frame 23 so that it can swing. The bucket 21 has a rectangular opening 211 that is large enough to surround the discharge port 30 and is formed so that the spacing narrows toward the bottom. The workpiece W, which is a bar material, has a center line parallel to the Z-axis when held by the spindle chuck, and the rectangular opening 211 has a longitudinal direction parallel to the Z-axis so that the bucket 21 can receive the workpiece W1 that falls in this state. Both longitudinal sides of the bucket 21 are pivotally supported by the support frame 23 by rotation shafts 231 that are parallel to the Z-axis, and the bucket 21 is attached so that it can swing back and forth. The rotation axis 231 is located close to the opening 211, and the center of gravity of the bucket 21 is located below the rotation axis 231. Therefore, in the normal state, the bucket 21 is in an open position with the opening 211 facing upward, as shown in Figure 3.

[0017] Next, the workpiece moving device 17 has a horizontal portion 221 of an arm 22 that penetrates a side surface 101 (see FIG. 3 ) of the machining chamber 10 and is rotatably supported by a bearing 24. Outside the machining chamber 10, a pinion gear 25 is fixed to the horizontal portion 221 and meshes with a rack gear 26 that is displaceable in the vertical direction (Y-axis direction). An operating cylinder 28 that is extendable in the Y-axis direction is fixed to a three-dimensionally assembled support block 27, and the rack gear 26 is connected to a piston rod 281 that extends downward. The operating cylinder 28 is a hydraulic cylinder that receives hydraulic oil from an oil tank inside the machine tool 1 via a pump and is extended and retracted by switching control of an electromagnetic switching valve. The bucket 21 is moved to the discharge position by extending the operating cylinder 28 shown in FIG. 4 , and conversely, moved to the receiving position by retracting the operating cylinder 28.

[0018] The bucket 21 at the discharge position shown in Figure 4 swings about 90 degrees from the receiving position shown in Figure 3 for receiving the workpiece W1 to a discharge position for discharging the workpiece W1. In the discharge position, the rectangular edge of the bucket 21 constituting the opening 211 is pressed against the wall panel 31 on the workbox 16 side, covering the discharge port 30. Therefore, the machine tool 1 is provided with a position switching mechanism that changes the position of the bucket 21 sent to the discharge position from the receiving position to the discharge position. Figure 5 is a diagram showing the state of the bucket 21 just before it reaches the discharge position.

[0019] The posture switching mechanism has a cam follower 29 that protrudes in the Z-axis direction attached to one of the shorter side surfaces of the bucket 21, and a cam member 19 that guides the movement of the cam follower 29 is provided on the back surface of the front door 12 next to the discharge port 30. The cam member 19 has a guide surface against which the abutted cam follower 29 rolls, and is shaped to swing the bucket 21 so that the opening 211 faces the discharge port 30. As shown in Figure 3, the cam member 19 is attached to the tip of a support bracket 39 that is fixed to the outside of the front opening 18 through which the front door 12 opens and closes.

[0020] When the front door 12 is closed, the discharge port 30 of the work box 16 formed therein faces the inside of the machining chamber 10, where coolant and chips are scattered. Therefore, an opening / closing shutter 32 is provided to close the discharge port 30 so that coolant and the like do not enter the work box 16. On the other hand, in order to send the workpiece W1 into the work box 16, it is necessary to open the opening / closing shutter 32. Therefore, in this embodiment, the opening / closing shutter 32 is configured to open in accordance with the swinging motion of the bucket 21 that discharges the workpiece W1.

[0021] The opening / closing shutter 32 is biased upward by a spring as described below, and is in a closed state as shown in FIG. 5. The opening / closing shutter 32 has an engagement protrusion 33 formed in the center of the upper part on the processing chamber 10 side. As shown in FIG. 3, the engagement protrusion 33 is elongated in the left-right direction, which is the opening and closing direction of the front door 12, and has a mountain-shaped inclined surface 331 formed so that the amount of protrusion from the opening / closing shutter 32 is large at the center and decreases toward both left and right sides in the opening and closing direction. Meanwhile, the bucket 21 has an engagement claw 34 formed thereon that can be hooked onto the engagement protrusion 33. The engagement claw 34 is attached to a longitudinal side of the bucket 21 so as to protrude toward the opening / closing shutter 32 along the open surface of the opening 211.

[0022] Next, Fig. 6 is a perspective view showing the mounting structure of the opening / closing shutter 32 from the inside of the work box 16 (outside the processing chamber 10), and Fig. 7 is a perspective view showing the opening / closing shutter 32. The work box 16 has a wall panel 31 on the processing chamber 10 side fixed to the front door 12. A discharge port 30 is formed in the wall panel 31, and a frame 35 is fixed so as to surround the discharge port 30. The opening / closing shutter 32 is assembled within the frame 35 so as to slide up and down.

[0023] The opening / closing shutter 32 has a shutter plate 41 facing the processing chamber 10 and a support plate 42 on the work box 16 side, which are arranged in parallel and are integrated by a connecting bar 43 at the upper end, etc. The work box 16 is blocked off from the inside of the processing chamber 10 by the shutter plate 41, to which connecting metal fittings 44 are fixed on both the left and right sides. Slide members 45 are fixed to the outside left and right sides of the connecting metal fittings 44, and are assembled so as to be slidable on vertical guide rails 36 fixed to the inside left and right sides of the frame 35. Thus, the opening / closing shutter 32 has the shutter plate 41 sliding up and down along the guide rails 36, closing the discharge port 30 in the raised position and opening it in the lowered position.

[0024] The opening / closing shutter 32 is maintained in a closed state by a coil spring 38 connected between the left and right connecting fittings 44 and the frame 35, and a constant upward biasing force is applied to the opening / closing shutter 32. Therefore, in order to open the opening / closing shutter 32, it is necessary to push it down against the biasing force of the coil spring 38. In this embodiment, the swinging motion of the bucket 21 described above is used to push down (open) the opening / closing shutter 32. Note that the coil spring 38 shown in the figure is simplified by its cylindrical shape (the same applies to the other coil springs shown below).

[0025] The opening / closing shutter 32 has an engagement protrusion 33 that protrudes into the machining chamber 10 so that the engagement claws 34 of the bucket 21 can be caught thereon. On the other hand, in the machine tool 1 of this embodiment, the work box 16 is formed integrally with the front door 12. Therefore, when the front door 12 is opened or closed, the protruding engagement protrusion 33 hits the edge of the front opening 18 (machine body cover 11), etc., creating resistance during opening and closing and hindering smooth sliding movement. In some cases, the engagement protrusion 33 may get caught, making it impossible to open the front door 12, or the engagement protrusion 33 may be damaged by a collision. Therefore, a retraction mechanism is provided in the opening / closing shutter 32 so that the front door 12 can be opened and closed smoothly.

[0026] 8 is a view taken along the arrows A-A in FIG. 7 showing the retraction mechanism of the opening / closing shutter 32, illustrating a normal state when the front door 12 is closed and a retracted state when the front door 12 is open. The opening / closing shutter 32 has a gate-shaped swing plate 46 in contact with the back surface of the shutter plate 41. An engagement protrusion 33 is integrally formed with the swing plate 46, and the engagement protrusion 33 protrudes toward the processing chamber 10 through a through-hole 411 formed in the shutter plate 41. A support block 47 is fixed to the lower center of the back surface of the shutter plate 41, and swing blocks 48 are pivotally supported on both the left and right sides of the support block 47 by horizontal support pins. The swing plate 46 is swingable, with the ends of its two parallel-extending forks fixed to the swing blocks 48 at two locations.

[0027] In the opening / closing shutter 32, a fixed distance is maintained between the shutter plate 41 and the support plate 42 by spacers 51, 52, and the swing plate 46 has a coil spring 53 attached between its fork and the support plate 42. Therefore, the swing plate 46 is supported by the support plate 42 and pressed against the shutter plate 41 by the biasing force of the coil spring 53, and as shown in the normal state in Figure 8, the engagement protrusion 33 protrudes significantly from the through-hole 411. On the other hand, as shown in the retracted state in Figure 8, when an external force F acts on the engagement protrusion 33, the swing plate 46 swings around the fulcrum 481, and the protrusion amount of the engagement protrusion 33 becomes smaller. The engagement protrusion 33 with the inclined surface 331 is subjected to the external force F when it comes into contact with another member when the front door 12 is opened or closed.

[0028] The retraction mechanism for the opening / closing shutter 32 is one solution to the problem that arises when the work box 16 is configured integrally with the front door 12. A similar problem can also arise when the bucket 21 is pressed against the wall panel 31 of the work box 16 at the discharge position. In other words, the bucket 21 pressed against the wall panel 31 creates resistance when the front door 12 is opened or closed. Therefore, a retraction mechanism is also provided in the workpiece moving device 17 as a solution to this problem. As shown by the dashed-dotted line in FIG. 4, the retraction mechanism for the bucket 21 is attached to a support plate 61 that extends below the support block 27. FIG. 9 is a cross-sectional view taken along arrow B in FIG. 4, showing the retraction mechanism for the bucket 21.

[0029] A holding plate 62 is fixed to the lower end of the support plate 61 at right angles. A guide pipe 63 is fixed to the center of the holding plate 62 from above, and a shaft 64 is inserted from below into the guide pipe 63, which penetrates vertically. A flange portion 641 formed in the middle of the shaft 64 abuts the underside of the holding plate 62, and a stopper 65 is screwed onto the upper end of the shaft 64 that protrudes from the guide pipe 63. A coil spring 67 is incorporated below the flange portion 641 so that the stopper 65 abuts against an abutment member 66 fixed to the lower end of the rack gear 26.

[0030] Rod members 68 are fixed to the holding plate 62 at positions on both sides of the shaft 64, and a lower plate 69 is supported by head portions 681 located at the lower ends of the rod members 68. A coil spring 67 is incorporated between the lower plate 69 and a flange portion 641 of the shaft 64, and the shaft 64 is biased upward (toward the rack gear 26). In addition, a restricting member 70 that restricts the downward movement of the shaft 64 is fixed to the lower plate 69, and the lowest position of the rack gear 26 can be adjusted by the amount that a stopper 65 is screwed onto the shaft 64.

[0031] Next, the operation of the machine tool 1 in this embodiment will be described. In workpiece machining, a bar material workpiece is inserted into the spindle of the spindle device from the bar feeder 2 outside the machine, and the tip portion protruding into the machining chamber 10 is gripped by the spindle chuck 15. The workpiece W is subjected to a predetermined machining process using the tools of the turret device. During workpiece machining, the bucket 21 in the position shown in Figure 4 covers the discharge port 30 in the machining chamber 10 (see Figure 10). Then, as the machined workpiece W1 is cut off by the cut-off bit of the turret device and falls, the bucket 21 moves to the receiving position as shown in Figure 3 and assumes a receiving position with the opening 211 facing up.

[0032] The movement of the bucket 21 from the discharge position to the receiving position is achieved by the contraction of the operating cylinder 28, which lifts the rack gear 26, causing the associated rotation of the pinion gear 25 and the pivoting of the arm 22. At this time, the bucket 21 swings within the support frame 23 due to its own weight, with the opening 211 facing upward. The cut-off workpiece W1 enters through the opening 211 and is received within the bucket 21. Next, the extension of the operating cylinder 28 pushes down the rack gear 26, causing the rotation of the pinion gear 25 and the pivoting of the arm 22, moving the bucket 21 from the receiving position to the discharge position.

[0033] As the bucket 11 moves toward the discharge position, the cam follower 29 comes into contact with the cam member 19 just before the discharge port 30, and in this state the arm 22 further pivots, causing the bucket 21 itself to swing relative to the support frame 23 due to the reaction force from the cam follower 29. As the bucket 21 swings in accordance with the cam member 19, the front portion thereof toward the discharge port 30 tilts downward, and the engaging claw 34 formed at the front portion in the direction of movement comes into contact from above with the engaging protrusion 33 of the opening / closing shutter 32. Then, as the operating cylinder 28 continues to extend, the bucket 21 continues to swing, and the opening / closing shutter 32 is pushed down.

[0034] 10 is a cross-sectional view showing the situation in which the workpiece W1 is discharged from the bucket 21 to the work box 16. The bucket 21 has its opening / closing shutter 32 opened, and the edge of its opening 211 is pressed against the wall panel 31 of the work box 16 so as to surround the discharge port 30. Therefore, the workpiece W1 in the bucket 21 is reliably placed in the work box W1 through the discharge port 30. The worker can open the lid of the work box 16 as needed and remove the machined workpiece W1 from the machine tool 1.

[0035] In the machining chamber 10, a predetermined amount of workpiece W is fed from the bar feeder 2, and the portion protruding from the spindle chuck 15 is machined. At this time, coolant is sprayed forcefully into the machining chamber 10, scattering chips and the like. If the discharge port 30 were open at that time, the coolant would leak out of the machine, and the chips and coolant that enter the work box 16 could damage the machined workpiece W1. In this regard, when the workpiece is machined, the discharge port 30 is blocked by the bucket 21 in the discharge position pressed against the wall panel 31, preventing coolant and the like from entering the work box 16.

[0036] Subsequently, when changing the stage of the machine tool 1, such as changing tools, an operator can perform work in the machining chamber 10 by opening the front door 12. However, because the front door 12, on which the work box 16 is mounted, is pressed against the bucket 21 by the wall panel 31, this pressing force creates resistance when opening the front door 12. At this time, hydraulic oil is supplied to the head side of the operating cylinder 28, which is in an extended state. Therefore, when the operator opens the front door 12, an electromagnetic switching valve provided in the hydraulic circuit is switched, and the piston of the operating cylinder 28 is pushed by the spring force of the coil spring 67, returning the hydraulic oil to the oil tank. Note that the electromagnetic switching valve is preferably controlled by, for example, a switch provided on the handle 121 of the front door 12.

[0037] The hydraulic oil pushed back by the operating cylinder 28 pushes up the rack gear 26 by a certain amount. That is, when the bucket 21 is pressed against the wall plate 31, the operating cylinder 28 is extended by the hydraulic pressure, the abutment member 66 of the rack gear 26 comes into contact with the stopper 65, the shaft 64 is pushed down, and the coil spring 67 is compressed. On the other hand, if no hydraulic pressure is applied to the operating cylinder 28, the coil spring 67 will extend, and the spring force will push up the rack gear 26 until the flange portion 641 comes into contact with the underside of the holding plate 62. The pinion gear 25 then rotates by the amount of this return stroke, and the bucket 21 moves away from the wall plate 31.

[0038] At this time, the amount of rotation of the pinion gear 25 in response to the return is small, but it corresponds to the distance the bucket 21 moves from the position where it blocks the discharge port 30 shown in FIG. 10 to the position where the engagement claws 34 are separated from the engagement protrusions 33 as shown in FIG. 5. Therefore, the bucket 21 avoids interference with the front door 12, allowing the worker to open and close the front door 12 smoothly without resistance from the bucket 21. Furthermore, the engagement protrusions 33 of the opening / closing shutter 32 are formed with mountain-shaped inclined surfaces 331 and are configured to be retractable so that the amount of protrusion from the shutter plate 41 is small. Therefore, even if the engagement protrusions 33 collide with something, the impact can be reduced. Furthermore, there is no significant resistance for the worker operating the opening / closing shutter 32 to open or close.

[0039] 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. For example, in the above embodiment, the swing plate 46 is used as a configuration in which the protrusion amount of the engagement protrusion 33 is reduced by an external force, but the engagement protrusion 33 itself may be supported by a biasing member. Also, in the above embodiment, the swing plate 46 integrated with the engagement protrusion 33 is biased by the coil spring 53, but a leaf spring or the like may be used as the biasing member.

[0040] DESCRIPTION OF SYMBOLS 1...machine tool 2...bar feeder 10...machining chamber 12...front door 15...spindle chuck 16...work box 17...work moving device 19...cam member 21...bucket 22...arm 25...pinion gear 26...rack gear 28...operating cylinder 29...cam follower 30...discharge port 32...opening / closing shutter 33...engaging protrusion 34...engaging claw 36...guide rail 38...coil spring 41...shutter plate 42...support plate 46...oscillating plate 53...coil spring 64...shaft 67...coil spring W (W1)...work

Claims

1. A machine tool in which a bar material workpiece fed into a spindle device is gripped by a spindle chuck in a processing chamber, and the workpiece is rotated and subjected to a specified processing operation using a tool, comprising: a work box protruding from the front side of a front door that opens and closes the processing chamber; an opening and closing shutter configured to close a discharge port formed in the front door that leads from the processing chamber to the workbox by being urged upward by a biasing member; a work moving device that moves a bucket that receives workpieces that drop from the position of the spindle chuck between its receiving position and a discharge position where the workpiece is discharged from the discharge port; and a position switching mechanism that swings the bucket as it moves to the discharge position, changing it from a workpiece receiving position to a discharge position that blocks the discharge port; the opening and closing shutter is formed with an engaging protrusion that protrudes into the processing chamber so as to be hooked onto the engaging claws of the bucket as it changes to the discharge position, and the engaging protrusion is configured so that the amount of protrusion becomes smaller when an external force is applied.

2. A machine tool as described in claim 1, wherein the opening / closing shutter is placed on a shutter plate facing the machining chamber and closing the discharge outlet, with a swinging plate on which the engaging protrusions are formed being in contact with the shutter plate, and the swinging plate is attached so as to be swingable relative to the shutter plate.

3. A machine tool as described in claim 2, wherein the opening / closing shutter has a shutter plate that is slidably mounted in the vertical direction and is urged upward by the urging member, a support plate that is parallel to the shutter plate and is integrally formed with the shutter plate, and the oscillating plate is urged toward the shutter plate by a urging member provided between the support plate and the oscillating plate.

4. A machine tool as described in claim 1, wherein the radial projection is elongated in the opening and closing direction of the opening and closing shutter, and has a mountain-shaped inclined surface formed so that the protrusion amount is large in the central part and decreases toward both sides.

5. A machine tool according to claim 1, wherein the edge of the opening of the bucket that receives the workpiece is pressed against the periphery of the discharge port, and the open / close shutter closes the open discharge port.

6. A machine tool as described in claim 5, wherein the workpiece moving device has a pinion gear meshing with a rack gear connected to a hydraulic cylinder, a support frame fixed to a rotating member which rotates integrally with the pinion gear, and the bucket is pivotally supported on the support frame so as to be able to swing freely, and the posture switching mechanism has a cam follower attached to the bucket and a cam member attached next to the discharge port to guide the movement of the cam follower.

7. A machine tool as described in claim 6, further comprising a retraction mechanism for returning the rack gear by a fixed stroke in the direction of contraction of the hydraulic cylinder by a biasing member compressed by the extension of the hydraulic cylinder, in relation to the workpiece moving device which presses the edge of the opening of the bucket against the area around the discharge port by the extension of the hydraulic cylinder.

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