Chuck assembly, machine tool and clamping method

Abstract

A chuck device, machine tool, and clamping method are disclosed. The chuck device initially uses a servo motor to move a lever forward and backward, causing a clamping mechanism to hold a workpiece. Then, a torque-adjusting disc spring extends and retracts to adjust the torque relative to the workpiece. When the servo motor rotates according to a predetermined amount indicated by torque data, the servo motor stops, and a clutch mechanism disengages. This ensures that the torque of the clamping mechanism holding the workpiece remains optimal, maintaining the torque of the clamping mechanism at an appropriate value without the need for constant pressure.

Description

Technical Field

[0001] This invention relates to a chuck device for clamping a workpiece as a machining object in various machine tools such as lathes, and improvements to machine tools having the chuck device, particularly a chuck device, machine tool and clamping method. Prior Technology

[0002] Regarding existing chuck devices, there is the "electric chuck device" described in Japanese Patent Application Publication No. 62-34708. This device uses a load cell to adjust the optimal clamping force in real time and automatically. The output of the induction motor is transmitted to the bolt shaft via a reducer and an electromagnetic clutch, causing the nut to rotate. The direction of this rotation determines whether the chuck is tightened or loosened. When the chuck jaws clamp the workpiece, the induction motor applies torque, causing the disc spring to deform. The load cell detects the reaction force generated at this time, and the central processing unit (CPU) controls the clamping force to match the reference value.

[0003] However, conventional chuck devices typically use hydraulic or pneumatic pressure, which must be applied continuously. In contrast, this chuck device is an electric chuck device that uses an induction motor to control the clamping force to a predetermined value. During workpiece machining, the clamping force of the chuck jaws is maintained while the induction motor is disengaged from the spindle via an electromagnetic clutch. That is, it does not rely on hydraulic pressure to continuously drive the induction motor. However, because it uses a load cell to adjust the optimal clamping force in real time and automatically, the control of the clamping force is more complex. Summary of the Invention

[0004] Therefore, the object of the present invention is to provide a chuck device, machine tool, and clamping method that can maintain the torque of the clamp at an appropriate value without the need for constant pressure.

[0005] Therefore, the chuck device of the present invention is used to clamp a workpiece. The chuck device includes a clamping mechanism, a drag rod, a rotary drive unit, a torque setting kit, a drag rod advance / retract unit, a housing, and a torque adjustment unit. The drag rod can advance and retract along a main axis direction to cause the clamping mechanism to clamp the workpiece. The torque setting kit is driven to rotate by the rotary drive unit. The drag rod advance / retract unit is disposed between the torque setting kit and the drag rod, and the rotation of the torque setting kit causes the drag rod to advance and retract. The torque adjustment unit is disposed between the torque setting kit and the housing, and the advance and retract of the drag rod adjusts the torque of the clamping mechanism clamping the workpiece.

[0006] The clamping method of the present invention uses the aforementioned chuck device to clamp the workpiece, wherein the rotary drive unit is used to move the drag bar forward and backward to clamp the workpiece, and after the workpiece is clamped, the torque adjustment unit is used to adjust the torque for the workpiece.

[0007] The machine tool of the present invention includes the aforementioned chuck device and clamps the workpiece using the aforementioned clamping method.

[0008] The advantage of this invention is that after the rotary drive unit drives the torque setting kit, the drag rod advance and retreat unit drives the drag rod to advance and retreat in the main shaft direction, and after clamping the workpiece, it cuts away from the rotary drive unit. Therefore, it is not necessary to apply pressure at all times to maintain the torque of the clamping mechanism at an appropriate value. Simple Explanation of the Diagram

[0009] Other features and effects of the present invention will be clearly presented in the embodiments with reference to the drawings, wherein: Figure 1 is a partial cross-sectional view of an embodiment of a chuck device of the present invention, showing that a drag bar of the chuck device moves toward the front end and releases a clamping mechanism; Figure 2 is a view similar to Figure 1, showing the tow bar moving towards the rear and clamping the clamping mechanism; Figures (A-1) and (B-1) in Figure 3 are enlarged views of the torque setting kit in Figures 1 and 2, while Figures (A-2) and (B-2) are front views of the clamping mechanism; and Figure 4 shows a flowchart of how a workpiece is clamped in this embodiment. Implementation

[0010] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0011] Referring to Figures 1 and 2, an embodiment of a chuck device 100 of the present invention is shown, illustrating a partial cross-section of the chuck device 100 along a main axis direction X (left-right direction in the figures). The chuck device 100 is applicable to a lathe (not shown).

[0012] The chuck device 100 includes a clamping mechanism 110, a drag bar 200, a housing 300, a torque setting mechanism 400, a drag bar advance / retreat unit 45, and a rotary drive unit 50. In the following description, one end of the clamping mechanism 110 is referred to as the "front end" and the other end as the "rear end".

[0013] Referring to Figure 3, the clamping mechanism 110 has multiple jaws 110A, 110B, 110C, and 110D, which clamp or hold a workpiece W by opening and closing the jaws 110A, 110B, 110C, and 110D. These structures are known technologies.

[0014] The drag bar 200 extends along the main shaft direction X and is disposed at the center of the chuck device 100. By moving the drag bar 200 forward and backward in the main shaft direction X, the jaws 110A, 110B, 110C, and 110D in the clamping mechanism 110 are opened and closed. When the drag bar 200 moves backward in the main shaft direction X, the distance between the jaws 110A, 110B, 110C, and 110D in the clamping mechanism 110 decreases and they close. When the drag bar 200 moves forward in the main shaft direction X, the distance between the jaws 110A, 110B, 110C, and 110D in the clamping mechanism 110 increases and they open.

[0015] Referring to Figures 1 to 3, the clamping mechanism 110 is disposed at the front end of the housing 300 and is used to clamp the workpiece W. The housing 300 is rotatably supported on a support housing 122 via a plurality of bearings 120. The housing 300 is disposed on the outer periphery of the drag rod 200 and supports the drag rod 200. The bearings 120 are disposed between the front of the housing 300 (right side in Figures 1 and 2) and the support housing 122. The bearings 120 are supported at predetermined positions between themselves and the housing 300 by a fixture or a stop 124. When machining the workpiece W, the housing 300 and the drag rod 200 rotate together. A space 310 is formed at the rear of the housing 300 (left side in Figures 1 and 2). Specifically, the space 310 is formed between the drag rod 200 and the housing 300. The outer periphery of the drag rod 200 is provided with two keyways 210 and 220. A key support 320 is fixed on the inner side of the housing 300.

[0016] The torque setting mechanism 400 is disposed in the space 310 and is used to clamp the workpiece W in the clamping mechanism 110. The torque setting mechanism 400 includes a torque setting kit 410 disposed on the outer periphery of the drag rod 200. A key 416 is provided on the inner side of the torque setting kit 410, and a key 418 is provided on the key support 320. The keyways 210 and 220 respectively engage with the keys 416 and 418. The keyways 210 and 220 and the keys 416 and 418 ensure the connection between the torque setting kit 410 and the drag rod 200.

[0017] The torque setting kit 410 has two bearings 412 and 414 at its two ends along the main shaft direction X. One bearing 412 is located between the key support 320 and the torque setting kit 410, and the other bearing 414 is located between the torque setting kit 410 and the housing 300. This allows the torque setting kit 410 to be supported so that it can rotate freely relative to the housing 300 and move forward and backward along the main shaft direction X. In the space 310 of the housing 300, a torque adjustment unit 42 is provided between the key support 320 and the side of the housing 300. This torque adjustment unit 42 is a torque adjusting disc spring 420 used to adjust the torque.

[0018] The torque setting kit 410 has two spring pressing portions 430 and 432 on its outer periphery, and two flange-shaped locking portions 440 and 442. The torque adjusting disc spring 420 is located between and faces the spring pressing portions 430 and 432. The spring pressing portions 430 and 432 are located between and abut against the locking portions 440 and 442. Through these structures, the spacing of the spring pressing portions 430 and 432 changes with the movement of the torque setting kit 410 to compress or release the torque adjusting disc spring 420, thereby changing the elastic force of the torque adjusting disc spring 420 and adjusting the torque of the clamping mechanism 110 in clamping the workpiece W.

[0019] The tow bar advance / retract unit 45 is an advance / retract threaded portion 450 located on the outer periphery of the tow bar 200 and the inner periphery of the torque setting kit 410. The advance / retract threaded portion 450 is formed by the engagement of a thread 452 on the outer peripheral surface of the tow bar 200 and a thread 454 on the inner peripheral surface of the torque setting kit 410. The advance / retract threaded portion 450 is spaced between the keyways 210 and 220.

[0020] The rotary drive unit 50 includes a control panel (control device) 500, a servo motor 510, a transmission gear 520, and a clutch mechanism 530. The control panel 500 has a memory 502. The torque setting kit 410 is used to set the torque transmitted from the rotation of the servo motor 510 to the clamping mechanism 110. In this embodiment, the servo motor 510 is used as a drive element capable of high-precision positioning, but a stepper motor can also be used. In this invention, the two are not distinguished, and are collectively referred to as "servo motor".

[0021] The torque setting mechanism 400 rotates the servo motor 510 according to a drive signal from the control panel 500, and this rotation is transmitted via the transmission gear 520 and the clutch mechanism 530. The clutch mechanism 530 has the function of sliding along with the torque setting assembly 410. The clutch mechanism 530 can be activated (ON) or deactivated (OFF) by receiving signals from the control panel 500.

[0022] The rotation of the servo motor 510 is transmitted to the torque setting kit 410 via the transmission gear 520 and the clutch mechanism 530. When the torque setting kit 410 rotates, the drag bar 200 moves forward and backward relative to the torque setting kit 410 in the spindle direction X by the action of the retractable thread 450. In particular, when the drag bar 200 moves forward and backward to clamp the workpiece W, the torque setting kit 410 moves forward and backward in the opposite direction.

[0023] Next, the torque used to clamp the workpiece W in the clamping mechanism 110 is controlled by the control panel 500. The memory 502 of the control panel 500 pre-calculates the relationship between the workpiece W and the optimal clamping torque and stores it as torque data 504. This torque data 504 includes: a. the material of the workpiece W; b. the shape of the workpiece W (diameter or whether it is hollow); and c. the processing state of the workpiece W (such as roughing or finishing, or the clamping opening / closing distance, etc.). The torque is individually determined based on the clamping conditions and state (clamping mode), whether only roughing or finishing is performed, or from roughing to finishing.

[0024] The torque data 504 indicated by the operator on the control panel 500 is output to the servo motor 510, and the servo motor 510 rotates according to the input data.

[0025] In the state shown in Figures 1 to 3(A1) and Figure 3(A-2) before clamping the workpiece W, the drag bar 200 is located on the side of the clamping mechanism 110 (right side of Figure 1), and the jaws 110A, 110B, 110C, and 110D of the clamping mechanism 110 are open. In the torque adjusting disc spring 420, the spring pressing part 432 abuts against the side away from the torque adjusting disc spring 420 (left side of Figure 1), so that the torque adjusting disc spring 420 is in an open state.

[0026] Referring to Figures 1 to 4, in this state, the method of clamping the workpiece W using the chuck device 100 includes the following steps:

[0027] Step SA: The operator mounts the workpiece W to be processed onto the clamping mechanism 110.

[0028] Step SB: Select the clamping mode of the workpiece W using the control panel 500.

[0029] Step SC: After the operation is started, the torque data 504 of the clamping mode selected by the control panel 500 is read from the memory 502 and output to the servo motor 510.

[0030] Step SD: The control panel 500 outputs an ON signal to the clutch mechanism 530.

[0031] Step SE: The servo motor 510 starts driving after the torque data 504 is input, and rotates according to the torque indicated by the torque data 504. This rotation is transmitted via the transmission gear 520 and the clutch mechanism 530 to the torque setting kit 410 of the torque setting mechanism 400, causing the torque setting kit 410 to rotate.

[0032] Step SF: The drag bar 200 is moved backward by the action of the threaded section 450 (left side in Figure 2, see the first arrow F1 pointing to the left in Figure 3 (AI)). Thereby, the jaws 110A, 110B, 110C, and 110D of the clamping mechanism 110 close and clamp the workpiece W with a predetermined torque (see Figure 3 (B-2)).

[0033] On the other hand, when the workpiece W is being clamped, if the servo motor 510 rotates more, the torque will increase dramatically. At this time, in the torque setting mechanism 400, the torque setting kit 410 will rotate relative to the drag rod 200 under the guidance of the feed thread 450. As a result, the torque setting kit 410 will move in the opposite direction relative to the drag rod 200 (see the second arrow F2 pointing to the right in Figure 3(B-1)).

[0034] When the torque setting kit 410 moves in the direction of the second arrow F2 toward the clamping mechanism 110, the locking portions 440 and 442 also move in the direction of the second arrow F2. Thereby, the spring pressing portion 430, located between the torque adjusting disc spring 420 and the key support portion 320, abuts against the key support portion 320 and stops moving. Conversely, the spring pressing portion 432, located on the opposite side of the torque adjusting disc spring 420, pushes the torque adjusting disc spring 420, causing the torque adjusting disc spring 420 to change from the open state (see Figures 1 and 3(A1)) to a closed state (see Figures 2 and 3(B-1)).

[0035] Therefore, the spring force of the torque adjusting disc spring 420 is applied from the torque setting kit 410 to the drag bar 200. In this way, the torque applied to the workpiece W by the rotation of the servo motor 510 can be adjusted to suppress a sharp increase in torque.

[0036] In other words, the servo motor 510 initially clamps the workpiece W by moving the drag bar 200 forward and backward, and then the torque adjustment disc spring 420 adjusts the torque on the workpiece W by extending (or opening and closing).

[0037] Step SG: After the servo motor 510 rotates according to the predetermined amount indicated by the torque data 504, the servo motor 510 stops.

[0038] Step SH: The clutch mechanism 530 is closed (OFF). However, the torque holding the workpiece W in the clamping mechanism 110 remains good.

[0039] As described above, after the workpiece W is clamped, the clutch mechanism 530 closes and is driven to rotate by a spindle motor (not shown). That is, by closing the clutch mechanism 530, the drive mechanism from the servo motor 510 to the clutch mechanism 530 is disengaged. The portion surrounded by the dashed line RW in Figure 2 rotates relative to the support housing 122 due to the bearings 120 to process the workpiece W. After the workpiece W is processed, the clutch mechanism 530 is activated, and the servo motor 510 rotates in the opposite direction, driving the torque setting kit 410 to rotate. The feed thread 450 moves the drag bar 200 forward, opening the jaws 110A, 110B, 110C, and 110D in the clamping mechanism 110, so that the workpiece W can be removed from the clamping mechanism 110.

[0040] As described above, the following effects can be obtained based on this embodiment.

[0041] a. Using the servo motor 510, the forward and backward threaded portion 450 of the torque setting kit 410 causes the drag bar 200 to move forward and backward to clamp the workpiece W, while the torque is adjusted by the extension and retraction of the torque adjusting disc spring 420. Therefore, the workpiece W can be clamped with appropriate torque.

[0042] b. After the workpiece W is clamped, the clutch mechanism 530 disengages from the servo motor 510 and the servo motor 510 stops. The threads 452 and 454 are screwed together to fix the position of the drag rod 200. The torque of the clamping mechanism 110 is maintained by the elastic force applied to the drag rod 200 by the torque adjustment disc spring 420 via the torque setting kit 410. Therefore, no electricity is required to maintain the torque when the workpiece W is being processed.

[0043] c. Even in the event of a power outage, the threads 452 and 454 are screwed together to fix the position of the drag rod 200, and the torque of the clamping mechanism 110 is maintained by the elastic force applied to the drag rod 200 by the torque adjusting disc spring 420 through the torque setting kit 410. The workpiece W can still be clamped, so there is no need to worry about the workpiece W falling.

[0044] d. When the workpiece W is being machined, the bearings 412 and 414 that cause the clamping mechanism 110 to rotate do not bear the load and reaction force of the spindle rotation, thus improving durability.

[0045] e. When the workpiece W is being processed, the entire chuck assembly 100 will rotate, thus suppressing heat generation.

[0046] f. As for the clutch mechanism 530, by adopting a ball clutch that can move in a straight line (sliding), hydraulic pulsation and resonance can be avoided.

[0047] g. The torque, chuck opening and closing distance, clamping mode, etc. can be selected on the control panel 500, so the operability is also good.

[0048] However, the present invention should not be limited to the embodiments described above. Various modifications or alterations can be made without departing from the spirit of the present invention, including, for example, the following.

[0049] 1. The shapes and dimensions of the various parts shown in this embodiment are examples, and the design can be changed to achieve the same function.

[0050] 2. The clamping mechanism 110 uses the opening and closing of the jaws 110A, 110B, 110C, and 110D to clamp the workpiece W, which can grip inward or outward.

[0051] 3. In this embodiment, although a servo motor is used, any drive element that can be positioned with high precision, such as a stepper motor, can be used.

[0052] 4. In this embodiment, when the drag bar 200 slides in the direction of the first arrow F1, the torque setting kit 410 slides in the direction of the second arrow F2. Depending on the direction in which the drag bar 200 drives the clamping mechanism 110 to open and close, the drag bar 200 and the torque setting kit 410 can also be configured to slide in opposite directions.

[0053] 5. In addition to lathes, the chuck device 100 of the present invention can also be applied to various machine tools such as machining centers, numerical control (NC) machines, computer numerical control (CNC) machines, milling machines, and laser cutting machines.

[0054] In summary, the chuck device 100 of the present invention, after the rotary drive unit 50 drives the torque setting kit 410, uses the trailing rod advance / retreat unit 45 to drive the trailing rod 200 forward and backward in the spindle direction X. After clamping the workpiece W, the clutch mechanism 530 disengages from the rotary drive unit 50, and the torque of the clamping mechanism 110 is maintained by the elastic force applied to the trailing rod 200 via the torque setting kit 410 by the torque adjustment unit 42. Therefore, the torque of the clamping mechanism 110 can be maintained at an appropriate value without constant pressure application, making it suitable for various working machines such as lathes, and thus effectively achieving the purpose of the present invention.

[0055] However, the above description is merely an embodiment of the present invention and should not be construed as limiting the scope of the present invention. Any simple equivalent changes and modifications made in accordance with the scope of the patent application and the contents of the patent specification of the present invention shall still fall within the scope of the patent of the present invention.

[0056] 100: Chuck device 110: Clamping mechanism 110A, 110B, 110C, 110D: Claw 120, 412, 414: Bearings 122: Support shell 124: Stop 200: Tow bar 210, 220: Keyway 300: Outer shell 310: Space 320: Key support section 400: Torque setting mechanism 410: Torque Setting Kit 416,418: Keys 42: Torque Adjustment Unit 420: Torque Adjusting Disc Spring 430, 432: Spring compression section 440, 442: Locking part 45: Tow bar forward / reverse unit 450: Infeed / Retract Thread Section 452, 454: Threaded threads 50: Rotary drive unit 500: Control Panel 502: Memory 504: Torque Data 510: Servo Motor 520: Transmission Gear Section 530: Clutch mechanism X: Main axis direction W: Workpiece RW: Dashed line F1: First Arrow F2: Second Arrow

Claims

1. A chuck device for clamping a workpiece, the chuck device comprising: a clamping mechanism; a drag rod capable of moving forward and backward along a spindle direction to clamp the workpiece by the clamping mechanism; a rotary drive unit including a servo motor and a clutch mechanism; a torque setting kit driven to rotate by the rotary drive unit, the rotation of the servo motor being transmitted to the torque setting kit via the clutch mechanism; a drag rod advance / retreat unit disposed between the torque setting kit and the drag rod, the drag rod advance / retreat unit being a threaded mechanism disposed at the outer periphery of the drag rod and the inner periphery of the torque setting kit, the drag rod being advanced / retreat by the rotation of the torque setting kit; a housing; and a torque adjustment unit disposed between the outer periphery of the torque setting kit and the housing, the torque of the clamping mechanism clamping the workpiece being adjusted by the advance / retreat of the drag rod, wherein during workpiece processing, the clutch mechanism can interrupt the rotational transmission of the servo motor to the torque setting kit.

2. The chuck device as claimed in claim 1, wherein, The torque adjustment unit is a disc spring that extends and retracts in response to the forward and backward movement of the torque setting kit in the spindle direction.

3. The chuck device as claimed in claim 1, wherein, The torque setting kit is located on the outer periphery of the tow bar.

4. The chuck device as claimed in claim 1, wherein, The rotary drive unit rotates the torque setting kit based on a pre-obtained torque data required by the workpiece.

5. A clamping method, wherein the workpiece is clamped using a chuck device described in any one of claims 1 to 4, wherein, The rotary drive unit is used to move the drag bar forward and backward to clamp the workpiece. After clamping the workpiece, the torque adjustment unit is used to adjust the torque for the workpiece.

6. A machine tool comprising a chuck device as described in any one of claims 1 to 4, and clamping the workpiece using the clamping method described in claim 5.

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