Machine tool

Abstract

The invention provides a machine tool capable of precisely determining poor clamping. The (NC) lathe (1) is provided with a first main shaft (4) having a collet chuck (48) for clamping a rod-shaped raw material (W1), and the NC lathe (1) processes the raw material (W1) clamped by the collet chuck (48) by repeatedly executing a processing operation to manufacture a plurality of products of the same shape, and is provided with a determination element (23). The determination element (23) determines at least one of machining time point information indicating which time point the machining operation is at and clamping force history information which is clamping force information when the collet chuck (48) clamps the raw material (W1) in the machining operation up to the last time, and the clamping of the raw material (W1) by the collet chuck (48) in the machining operation of this time on the basis of the clamping force history information, i.e., machining time point information indicating which time point the machining operation is at and the clamping force information when the collet chuck (48) clamps the raw material (W1) in the machining operation up to the last time. The current clamping force information is the current clamping force information, and the clamping failure of the first main shaft (4) is determined.

Description

Technical Field

[0001] This invention relates to a machine tool for processing raw materials held by a spindle. Background Technology

[0002] Machine tools are known for processing rod-shaped raw materials held by a spindle (see, for example, reference 1). The spindle is rotatably supported by a spindle table. A clamping part is provided on the spindle, which can change between a clamping state holding the raw material and a clamping-release state releasing the raw material. Furthermore, a safety monitoring system has been proposed that determines clamping failure by installing a sensor on the clamping part (see, for example, reference 2).

[0003] [Existing technical documents]

[0004] [Professional Literature]

[0005] [Professional Document 1] JP 2020-97075

[0006] [Professional Document 2] JP 2011-121148 Summary of the Invention

[0007] [The problem the invention aims to solve]

[0008] However, in the safety monitoring system of professional literature 2, only the output of the sensor installed on the clamping part is used to determine the abnormality. Therefore, there is a problem that it can only make a uniform judgment, but it is difficult to accurately determine the clamping failure of the clamping part.

[0009] The present invention was made in view of the above-mentioned problems, and its object is to provide a machine tool that can accurately determine clamping defects.

[0010] [Technical means to solve the problem]

[0011] The machine tool of the present invention that solves the aforementioned problem

[0012] A machine tool equipped with a spindle having a clamping section for holding rod-shaped raw materials, which repeatedly performs machining operations to process the raw materials held by the clamping section, thereby manufacturing multiple products of the same shape.

[0013] The device includes a determination element that performs a determination on the spindle clamping failure based on at least one of the following: processing time point information indicating which time point the processing action is at; clamping force history information when the clamping part clamps the raw material in the previous processing action; and current clamping force information when the clamping part clamps the raw material in the current processing action.

[0014] According to the machine tool, the determination element performs a determination on clamping defects based on at least one of the processing time point information and the clamping force history information, as well as the current clamping force information, and thus can accurately determine clamping defects.

[0015] Here, the machine tool can perform multiple cycles of the machining action that produces one product as one cycle. The determination element can also classify and determine the type of clamping defect. Moreover, the determination element can also classify and determine clamping defects according to various causes.

[0016] In this machine tool,

[0017] The determination element can determine that poor clamping occurred due to preparation error when the processing time information is information representing the initial processing action, and if the clamping force in the current clamping force information is outside the specified range.

[0018] According to the machine tool, poor clamping force is caused by errors in preparation, and therefore, the problem is easy to handle.

[0019] In this machine tool,

[0020] A feeder is connected to the main shaft, which stores multiple raw materials and sequentially supplies the stored raw materials to the main shaft.

[0021] When the processing time information indicates the processing action after the feeder has just re-supplied the raw material to the spindle, if the clamping force in the current clamping force information is outside the specified range, the determination element determines that the raw material supplied by the feeder has a poor diameter, resulting in poor clamping.

[0022] According to the machine tool, poor clamping force is caused by poor diameter of raw materials, so the problem is easy to handle.

[0023] In this machine tool,

[0024] The determination element can determine that a clamping failure has occurred when the change in the clamping force in the current clamping force information relative to the clamping force in the clamping force history information exceeds a threshold.

[0025] Therefore, for example, the entry of a small foreign object into the clamping part can be determined as a poor clamping condition.

[0026] Moreover, in this machine tool,

[0027] The determination element can classify the types of clamping defects based on whether the clamping force in the current clamping force information increases or decreases relative to the clamping force in the clamping force history information when the change exceeds the threshold.

[0028] This allows for the accurate classification of different types of clamping defects.

[0029] Moreover, in this machine tool,

[0030] It may include a control device that, when the change exceeds the threshold, and the clamping force in the current clamping force information increases relative to the clamping force in the clamping force history information, performs a removal action to remove foreign objects that have entered the clamping part.

[0031] When the change exceeds the threshold, and the clamping force in the current clamping force information increases relative to the clamping force in the clamping force history information, foreign objects such as debris are likely to enter the clamping part. This removal action reduces the possibility of damage to the raw material caused by foreign objects entering the clamping part. Furthermore, it reduces the possibility of the processing action stopping due to poor clamping.

[0032] Here, the removal action includes releasing the clamping part from the raw material. Furthermore, the removal action may include moving the spindle after releasing the clamping part from the raw material. Moreover, the removal action may include spraying fluid into the clamping part after releasing the clamping part from the raw material.

[0033] Moreover, in this machine tool,

[0034] The determination element can classify the types of clamping failures based on a combination of whether the clamping force in the current clamping force information is outside a specified range and whether the change in the clamping force in the current clamping force information relative to the clamping force in the clamping force history information exceeds a threshold.

[0035] This machine tool allows for more precise determination of the types of clamping defects.

[0036] Moreover, this machine tool may include:

[0037] A tool holder, on which a tool for processing the raw material is mounted, and which moves together with the tool;

[0038] Storage element, storing movement correction values ​​used to correct a specified movement position specified in the machining program; and

[0039] The correction value rewriting element rewrites the shift correction value stored in the storage element;

[0040] When the determination element determines that the clamping force in the current clamping force information is outside the specified range and the change in the clamping force in the current clamping force information relative to the clamping force in the clamping force history information does not exceed a threshold, the correction value rewriting element rewrites the movement correction value stored in the storage element.

[0041] When the clamping force of the clamping part gradually changes due to thermal displacement or other reasons, the correction value rewriting element will rewrite the movement correction value to a suitable value accordingly, thereby improving the machining accuracy.

[0042] [Invention Effects]

[0043] According to the present invention, a machine tool capable of accurately determining clamping defects can be provided. Attached Figure Description

[0044] Figure 1 This is a top view that simply shows the internal structure of the NC lathe in this embodiment.

[0045] Figure 2 It is Figure 1 The cross-sectional view shown is taken from above after the first spindle table and the first spindle are cut along the horizontal plane passing through the axis of the first spindle.

[0046] Figure 3 It is Figure 1 The diagram shows a three-dimensional cross-sectional view of the first spindle stage and the first spindle, cut off from a portion of the first spindle stage.

[0047] Figure 4 yes Figure 1 The control block diagram of the NC lathe is shown.

[0048] Figure 5 It means to adopt Figure 1 The flowchart of the first machining action of the first spindle is shown.

[0049] Figure 6 It means to adopt Figure 1 The flowchart of the first machining action of the first spindle is shown.

[0050] Figure 7 This is a diagram showing an example of the clamping force of each clamping action of the first spindle 4 from the initial machining action to the final machining action.

[0051] Figure 8 It means to adopt Figure 1 The flowchart of the second machining action of the second spindle is shown.

[0052] Figure 9 It means to adopt Figure 1 The flowchart of the second machining action of the second spindle is shown. Detailed Implementation

[0053] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In this embodiment, an example of applying the present invention to a Swiss-type Numerical Control (NC) lathe will be used for illustration. That is, the NC lathe described below is equivalent to an example of a machine tool.

[0054] Figure 1 This is a top view simply illustrating the internal structure of the NC lathe 1 according to this embodiment. Figure 1 The text only indicates the 10 feeders.

[0055] like Figure 1 As shown, the NC lathe 1 internally includes a control device 2, a first spindle head 3, a first spindle 4, a guide sleeve 5, a first tool post 6, a second spindle head 7, a second spindle 8, and a second tool post 9. Furthermore, a feeder 10 is connected to the NC lathe 1. These NC lathe 1 and feeder 10 form an NC lathe system. This NC lathe system is an example of a machine tool system. The control device 2 is a computer that operates the first spindle head 3, first spindle 4, first tool post 6, second spindle head 7, second spindle 8, and second tool post 9 according to an NC program. In addition to operations using the NC program, the operation can also be controlled from the operation unit 11 (see reference 11). Figure 4 The NC lathe 1 can be operated by directly inputting commands into the control device 2.

[0056] The first spindle stage 3 moves along the Z1 axis, together with the first spindle 4, according to a signal from the control device 2. The Z1 axis is horizontal. Figure 1 The center represents the left-right direction. The first spindle 4 is rotatably supported by the first spindle table 3. Furthermore, a first rotating shaft motor 31 is provided on the first spindle table 3, and the first rotating shaft motor 31 is located between the first spindle table 3 and the first spindle 4 (see reference). Figure 2 The first shaft motor 31 rotates after receiving a signal from the control device 2, thereby causing the first main shaft 4 to rotate around the first axis CL1. The direction of the first axis CL1 is consistent with the direction of the Z1 axis.

[0057] The first spindle 4 can change between a clamping state holding a long rod-shaped raw material W1 inserted therein and a clamping-free state releasing the clamp on the raw material W1. This first spindle 4 is equivalent to an example of a spindle. The raw material W1 held by the first spindle 4 rotates together with the first spindle 4 around the first axis CL1 by rotating the first spindle 4. The structure of the first spindle table 3 and the first spindle 4 will be described in detail below. At the front end of the first spindle 4, a collet chuck 48, which will be described in detail below, is provided. This collet chuck 48 is equivalent to an example of a clamping part.

[0058] The guide sleeve 5 is fixed inside the NC lathe 1. The guide sleeve 5 supports the front end of the raw material W1 protruding from the first spindle 4, and this front end can slide freely in the Z1 axis direction. The unsupported portion of the raw material W1 in the guide sleeve 5 can rotate synchronously with the first spindle 4 around the first axis CL1. That is, the first axis CL1 is also the axis of rotation of the portion of the raw material W1 supported by the guide sleeve 5. Because of the guide sleeve 5, bending of the raw material W1 during machining can be suppressed; therefore, particularly slender raw materials W1 can be machined with high precision.

[0059] The first tool post 6 can move along the X1 axis (orthogonal to the Z1 axis and oriented horizontally) and the Y1 axis (oriented vertically). This first tool post 6 is an example of a tool post. After receiving a signal from the control device 2, the first tool post 6 moves along the X1 axis and the Y1 axis. Figure 1 In the center, the vertical direction is the X1 axis, and the direction orthogonal to the paper is the Y1 axis. The first spindle tool T1 for machining the raw material W1 is mounted on the first tool holder 6. Figure 1 The diagram shows the first spindle tool T1 mounted on the first tool post 6. Various first spindle tools T1, including turning tools for external diameter machining and parting-off machining, are mounted side-by-side along the Y1 axis on the first tool post 6. By moving the first tool post 6 along the Y1 axis, any one of these first spindle tools T1 can be selected. Furthermore, by moving the first tool post 6 along the X1 axis, the selected first spindle tool T1 is inserted into the raw material W1 held by the first spindle 4 to machine the raw material W1. Moreover, the first tool post 6 is provided with a first coolant discharge section 61 that discharges coolant toward the first spindle tool T1 or the raw material W1.

[0060] The second spindle stage 7 moves along with the second spindle 8 in the X2 and Z2 axes directions according to a signal from the control device 2. The X2 axis direction is the same as the X1 axis direction described above, and the Z2 axis direction is the same as the Z1 axis direction described above. A second rotating shaft motor (not shown) or similar built-in motor is provided on the second spindle stage 7. By rotating this second rotating shaft motor after receiving a signal from the control device 2, the second spindle 8 rotates around the second axis CL2. The direction of the second axis CL2 is consistent with the Z2 axis direction.

[0061] The cut-off raw material W2, processed by the first spindle 4 and cut by the cutting tool, is transferred to the second spindle 8. The second spindle 8 can switch between a clamping state holding the cut-off raw material W2 transferred from the first spindle 4 and a released state, whereby the clamping of the cut-off raw material W2 is released. This second spindle 8 is equivalent to an example of a spindle. By rotating the second spindle 8, the cut-off raw material W2 held by the second spindle 8 rotates together with the second spindle 8 around the second axis CL2. A second collet 81 is provided on the front end side of the second spindle 8. When the second spindle 8 is a spindle, this second collet 81 is equivalent to an example of a clamping part.

[0062] The second tool holder 9 moves in the Y2 axis direction according to the signal from the control device 2. This Y2 axis direction is the same as the Y1 axis direction mentioned above, that is, the perpendicular direction. Multiple second spindle tools T2 are mounted on the second tool holder 9 to process the cut raw material W2 held by the second spindle 8. Figure 1 The diagram shows the second spindle tool T2 mounted on the second tool post 9. Various second spindle tools T2, such as drills and end mills, are mounted on the second tool post 9. The second spindle tools T2 are mounted side-by-side not only along the X2 axis but also along the Y2 axis. By moving the second spindle head 7 along the X2 axis and the second tool post 9 along the Y2 axis, any one of these second spindle tools T2 can be selected. Furthermore, by moving the second spindle head 7 along the Z2 axis, the cut-off end portion of the raw material W2, held by the second spindle 8, is machined. The second tool post 9 is also provided with a second coolant discharge section 91 that discharges coolant to the second spindle tool T2, the cut-off raw material W2, or the second spindle 8.

[0063] The feeder 10 is a device that supplies long, rod-shaped raw materials W1 to the NC lathe 1. The feeder 10 is positioned side-by-side with the NC lathe 1, further rearward than the first spindle 4. The feeder 10 stores multiple raw materials W1. The feeder 10 has a built-in feed control device 101 (see reference 101) for controlling the feeder 10. Figure 4 The feeding control device 101 operates the feeder 10 according to instructions from the control device 2 of the NC lathe 1. Furthermore, it appropriately sends status information of the feeder 10 to the control device 2. According to instructions from the control device 2, the feeder 10 extracts and discharges the residual material (which has shortened due to the machining operation of the NC lathe 1) that serves as raw material W1 from the NC lathe 1. After discharging the residual material, the feeder 10 sequentially feeds new raw material W1 to the NC lathe 1. The action of extracting and discharging the residual material from the NC lathe 1 and then feeding new raw material W1 to the NC lathe 1 is equivalent to a raw material W1 replacement action.

[0064] Figure 2 It is Figure 1 The diagram shows a cross-sectional view of the first spindle stage 3 and the first spindle 4 as seen from above, cut along a horizontal plane passing through the first axis CL1. Note that the shading used in this description does not indicate the cross-section in the accompanying drawings.

[0065] like Figure 2 As shown, the first spindle 4 is generally cylindrical with an axis in the direction of the first axis CL1. The first spindle 4 is rotatably supported on the first spindle table 3 by bearing 39. The first spindle 4 has a spindle body 41, a shifter 42, a jaw assembly 43, an adjusting nut 44, a push sleeve 45, a collet sleeve 46, a coil spring 47, a collet chuck 48, and a shaft cover 49.

[0066] The main spindle body 41 serves as the base for the first main spindle 4 and is a cylindrical body extending along the Z1 axis. The gear shifter 42 is located on the rear end side of the first main spindle 4. Additionally, Figure 2 In the diagram, the left side shows the rear end of the first spindle 4, and the right side shows the front end of the first spindle 4. The shifter 42 is generally cylindrical and is mounted on the spindle body 41 in a way that allows it to slide along the Z1 axis by sliding its inner circumferential surface against the outer circumferential surface of the spindle body 41. Figure 2 As shown, a cam surface 42a is formed on the outer peripheral surface of the shifter 42. The cam surface 42a, starting from the rear end side of the first main shaft 4, sequentially includes a small-diameter surface with a certain outer diameter, a changing surface with a gradually increasing outer diameter, and a large-diameter surface with a certain outer diameter. The shifter 42 slides along the Z1 axis direction by driving the cylinder 32. Figure 2 The diagram shows the shifter 42 located on the front end side closest to the first spindle 4.

[0067] Two claw components 43 are mounted on the main shaft body 41 in a manner that allows them to swing around a claw shaft 431. At the front end of each claw component 43, a claw front end portion 43b is formed, which engages with the cam surface 42a of the shifter 42 and functions as a cam follower. The claw front end portion 43b moves closer to or further away from the first axis CL1 along the cam surface 42a depending on the sliding of the shifter 42, thereby causing the claw component 43 to swing around the claw shaft 431. A sleeve pushing portion 43a is formed on the claw component 43, which contacts the rear end of a pushing sleeve 45.

[0068] The adjusting nut 44 is screwed into the spindle body 41 at the rearmost part of the first spindle 4. A female thread is formed on the inner side of the adjusting nut 44, which engages with the male thread formed at the rear end of the spindle body 41. By rotating the adjusting nut 44 in the tightening direction, the claw member 43, the push sleeve 45, and the collet sleeve 46 move together with the adjusting nut 44 toward the front end of the first spindle 4. As a result, the inner diameter of the collet 48 in the clamping state becomes relatively smaller, and the raw material W1 of the first spindle 4 (refer to...) Figure 1 The clamping force of the material W1 on the first spindle 41 increases. Conversely, by rotating the adjusting nut 44 in the loosening direction, the claw component 43, the push sleeve 45, and the collet sleeve 46 move together with the adjusting nut 44 toward the rear end of the first spindle 4. As a result, the inner diameter of the collet 48 in the clamping state becomes relatively larger, and the clamping force of the material W1 on the first spindle 4 decreases. In other words, the clamping force of the material W1 in the clamping state on the first spindle 4 is adjusted by adjusting the adjusting nut 44. The adjusting nut 44 is C-shaped with a radial notch when viewed from the rear end to the front end of the first spindle 4. The width of the notch can be changed by a screw (not shown). After the clamping force is adjusted using the adjusting nut 44, the width of the notch is reduced using the screw, thereby fixing the adjusting nut 44 to the spindle body 41 in the adjusted position.

[0069] The push sleeve 45 is a cylinder disposed inside the main spindle body 41, with its front end contacting the rear end of the collet sleeve 46. The push sleeve 45 and the collet sleeve 46 move in the opposite direction to the shifter 42 by the movement of the shifter 42 in the Z1 axis direction. Specifically, the shifter 42 slides towards the rear end of the first main spindle 4, thereby causing the front end portion 43b of the jaw member 43 to push against the cam surface 42a of the shifter 42 and move away from the first axis CL1. As a result, the push sleeve 45 and the collet sleeve 46 push against the sleeve pushing portion 43a of the jaw member 43 and move towards the front end of the first main spindle 4, thereby reducing the diameter of the collet chuck 48, and the first main spindle 4 is in a clamping state for holding the raw material W1.

[0070] Conversely, by sliding the shifter 42 toward the front end of the first spindle 4, the front end portion 43b of the claw component 43 moves along the cam surface 42a of the shifter 42 toward the first axis CL1. As a result, the push sleeve 45 and the chuck sleeve 46 move toward the rear end of the first spindle 4, thereby expanding the diameter of the collet chuck 48, and the first spindle 4 is in a released state, freeing it from clamping the raw material W1.

[0071] The helical spring 47 constantly pushes the collet sleeve 46 toward the rear end and constantly pushes the collet 48 toward the front end. As a result, the pressing sleeve 45 is also pushed toward the rear end via the collet sleeve 46, and the pressing sleeve 45 pushes the sleeve pressing part 43a toward the rear end.

[0072] The inner circumferential surface of the front end of the collet sleeve 46 is an inclined surface with a diameter that increases towards the front end. The outer circumferential surface of the front end of the collet 48 is also an inclined surface with a diameter that increases towards the front end. In the collet 48, a total of three slits are formed at 120° intervals along the circumference, extending continuously from the front end to a hole formed near the center in the Z1 axis direction. These holes and slits allow for radial expansion and contraction of the collet 48, particularly on the front end side. Figure 2 In the released state shown, the chuck sleeve 46 is located at the rear end, so the inner circumferential surface of the front end of the chuck sleeve 46 exerts almost no pushing force on the outer circumferential surface of the front end of the collet 48 in a radially inward direction, and the collet 48 expands its diameter using its own elasticity. Conversely, in the clamping state, the chuck sleeve 46 is located at the front end, and the inner circumferential surface of the front end of the chuck sleeve 46 pushes the outer circumferential surface of the front end of the collet 48 in a radially inward direction, causing the collet 48 to shrink in diameter.

[0073] The spindle cover 49 is bowl-shaped, with a circular through-hole extending along the Z1 axis in its center. The front end face of the collet 48 contacts the bottom portion of the spindle cover 49, which corresponds to the bowl shape, thereby restricting the movement of the collet 48 towards the front end. The collet 48 is pressed by a helical spring 47, thus being continuously pressed towards the spindle cover 49. The spindle cover 49 is fixed to the spindle body 41 by engaging a female thread formed on the inner side of its bowl-shaped edge with a male thread formed on the front end portion of the spindle body 41.

[0074] The first spindle stage 3 has a first rotating shaft motor 31, a cylinder 32, and a shift lever 33. The first rotating shaft motor 31 is a built-in motor located on the first spindle stage 3. As described above, by rotating the first rotating shaft motor 31, the first spindle 4, supported by the first spindle stage 3 via the bearing 39, rotates around the first axis CL1.

[0075] Cylinder 32 includes cylinder tube 321, piston 322, and piston rod 323. Cylinder tube 321 is the housing of cylinder 32 and is cylindrical. Piston 322 is disposed within cylinder tube 321 such that it is in contact with the inner circumferential surface of cylinder tube 321 and can move to one side or the other. Piston rod 323 is rod-shaped with one end fixed to piston 322. The other end of piston rod 323 is connected to shift lever 33. By supplying air to cylinder 32, piston 322 moves, and piston rod 323 moves in or out of cylinder tube 321. Figure 2 The image shows the piston 322 moving to the farthest side while the piston rod 323 is in its maximum position.

[0076] The shift lever 33 swings freely around the pivot 331. One end of the shift lever 33 is rotatably connected to the other end of the piston rod 323 via a connecting pin 332. The other end of the shift lever 33 is connected to the shifter 42. The shift lever 33 is oscillated by the drive cylinder 32, which causes the shifter 42 to slide along the Z1 axis. The cylinder 32, shift lever 33, shifter 42, pawl assembly 43, push sleeve 45, collet sleeve 46, and coil spring 47 described above form a sleeve expansion and contraction mechanism that causes the collet chuck 48 to expand and contract.

[0077] Figure 3 It is Figure 1 The diagram shows a three-dimensional cross-sectional view of the first spindle stage 3 and the first spindle 4, obtained by cutting off a portion of the first spindle stage 3.

[0078] like Figure 3 As shown, the shift lever 33 is roughly U-shaped when viewed from the rear end to the front end. A strain sensing element 333 is mounted on the side of the rear end of the shift lever 33. The strain sensing element 333 is a strain gauge, which transmits the driving force of the cylinder 32 from the cylinder 32 to the collet chuck 48 (see reference). Figure 2 The strain generated on the shift lever 33 is detected during operation. Signal line 334 is connected to the strain detection element 333. The strain signal detected by the strain detection element 333 is sent to the control device 2 (see reference 2) via signal line 334. Figure 1 The strain detection element 333 detects the strain of the shift lever 33 at its mounting location.

[0079] right Figure 1 The structure of the second spindle 8, which clamps and releases the cut raw material W2, is the same as that of the first spindle table 3 and the first spindle 4, therefore detailed description is omitted. Additionally, the second spindle table 7 has a second shift lever (not shown), on which a second strain detection element (not shown) is mounted to detect the strain generated by the second shift lever. Furthermore, a known blower device is provided on the second spindle 8, which blows air from the rear end to the front end of the second spindle 8 along the outer peripheral surface of the cut raw material W2 inside the second spindle 8. The operation of the blower device is controlled by the control device 2. The cut raw material W2 on the second spindle 8 corresponds to an example of a raw material.

[0080] Figure 4 yes Figure 1 The control block diagram of NC lathe 1 is shown below. Additionally... Figure 4 Only control structures that are particularly relevant to this embodiment are shown.

[0081] like Figure 4As shown, the NC lathe 1 includes an operation unit 11 and a display unit 12, which serve as the interface with the operator. The operation unit 11 is an input device for operating the NC lathe 1. The operation unit 11 consists of multiple buttons or keys that accept input operations from the operator for the NC lathe 1. Alternatively, the operation unit 11 can be a touch panel integrated with the display unit 12. The display unit 12 is a display that shows various information related to the NC lathe 1, such as the NC program, various settings, and error messages.

[0082] The control device 2 includes a storage element 21, a clamping force output element 22, a judgment element 23, and a correction value rewriting element 24. The storage element 21 stores the control program, NC program, and various information, including non-volatile memory and volatile memory. Furthermore, the storage element 21 includes a machining time point information storage unit 211, a first clamping force information storage unit 212, a second clamping force information storage unit 213, a movement correction value storage unit 214, and a counter 215.

[0083] NC lathe 1 repeatedly executes one cycle of machining operations according to the NC program, thereby producing multiple products of the same shape. Each execution of this one-cycle machining operation produces one product. In most cases, one cycle of machining operations includes a first machining operation using the first spindle 4 and a second machining operation using the second spindle. However, depending on the product shape, sometimes the product can be produced using only the first machining operation. At the beginning of the first machining operation, a clamping instruction is executed to hold the raw material W1. Furthermore, at the beginning of the second machining operation, a clamping instruction is also executed to hold and cut the raw material W2.

[0084] The processing time point information storage unit 211 stores information about the current processing action, from the start of the initial processing action to the completion of the final processing action. This information about the current processing action is equivalent to processing time point information. Specifically, the processing time point information storage unit 211 stores information indicating the initial processing action, or information indicating the processing action after the replacement of raw material W1 and the resupply of new raw material W1 to the first spindle 4.

[0085] In the first clamping force information storage unit 212, clamping force information of the raw material W1 is stored each time the collet chuck 48 clamps the raw material W1, starting from the initial machining operation. The clamping force output element 22, described later, outputs the clamping force of the collet chuck 48 on the raw material W1. The clamping force information stored in the first clamping force information storage unit 212 also includes information about the time when the clamping force was stored. In addition, the information accompanying the clamping force information can be other time information or sequential information such as the storage order, as long as the clamping order can be clearly defined. In the following description, the clamping force information of the collet chuck 48 when clamping the raw material W1 in the previous machining operation from the clamping force information stored in the first clamping force information storage unit 212 is referred to as the first clamping force history information. This first clamping force history information is equivalent to an example of clamping force history information. Furthermore, in the following description, the clamping force information stored in the first clamping force information storage unit 212 when the collet chuck 48 clamps the raw material W1 in the current machining operation is referred to as the first current clamping force information. This first current clamping force information is equivalent to an example of the current clamping force information. Alternatively, the information in the clamping force information stored in the first clamping force information storage unit 212, such as the average value of the clamping force when the collet chuck 48 clamps the raw material W1 in multiple previous machining operations (for example, a total of 2 operations including the previous and the one before that), can also be used as the first clamping force history information.

[0086] In the second clamping force information storage unit 213, from the start of the initial processing operation, each time the second collet chuck 81 has finished clamping and cutting the raw material W2, the clamping force information of the cut raw material W2 is saved. The clamping force output element 22 also outputs the clamping force of the second collet chuck 81 on the cut raw material W2. The clamping force information stored in the second clamping force information storage unit 213 also includes information on the time when the clamping force was saved. As long as the clamping order can be clearly defined, the information accompanying the clamping force information can be information from other times, or it can be sequential information such as the saving order. In the following description, the clamping force information in the second clamping force information storage unit 213 at the time when the second collet chuck 81 finished clamping and cutting the raw material W2 in the last processing operation is referred to as the second clamping force history information. This second clamping force history information is equivalent to an example of clamping force history information. Furthermore, in the following description, the clamping force information stored in the second clamping force information storage unit 213 at the time when the second collet chuck 81 has finished clamping and cutting the raw material W2 in the current processing operation is referred to as the second current clamping force information. This second current clamping force information is equivalent to an example of the current clamping force information. In addition, the information such as the average value of the clamping force at the time when the second collet chuck 81 has finished clamping and cutting the raw material W2 in multiple processing operations before the last time, stored in the second clamping force information storage unit 213, can also be used as the second clamping force history information.

[0087] The movement correction value storage unit 214 stores movement correction values ​​used to correct the movement position of the first tool post 6. The NC control device 2 moves the first tool post 6 to the position specified by the NC program plus the movement correction value, thereby correcting errors caused by wear of the first spindle tool T1, wear of structural components of the NC lathe 1, thermal displacement of various components, etc. This improves machining accuracy during the first machining operation. Furthermore, the movement correction value storage unit 214 also stores a second movement correction value used to correct the movement position of the second spindle table 7. The NC control device 2 moves the second spindle table 7 or the second tool post 9 to the position obtained by adding the second movement correction value, thereby improving machining accuracy during the second machining operation.

[0088] Counter 215 stores the number of specific actions of the NC lathe 1. These specific actions include the number of processed products (i.e., the number of processing actions), the number of foreign object removal actions in the first spindle 4, the number of foreign object removal actions in the second spindle 8, and the number of reprocessing actions. The details of these removal and reprocessing actions will be described below. Hereinafter, the counter representing the number of processing actions will be called the production count counter, the counter representing the number of removal actions in the first spindle 4 will be called the first removal count counter, the counter representing the number of removal actions in the second spindle 8 will be called the second removal count counter, and the counter representing the number of reprocessing actions will be called the reprocessing counter.

[0089] The clamping force output element 22 outputs the clamping force of the collet 48 on the raw material W1 based on the strain of the shift lever 33 detected by the strain detection element 333 during the period from the start of the clamping action of the first spindle 4 to the clamping of the raw material W1. The clamping force output element 22 has data relating the maximum value of the strain generated by the strain detection element 333 when the shift lever 33 swings to the clamping force of the collet 48 on the raw material W1. Moreover, using this data, the clamping force of the collet 48 on the raw material W1 is output each time the collet 48 clamps the raw material W1. Similarly, the clamping force output element 22 outputs the clamping force of the cut raw material W2 on the second spindle 8 each time the second spindle 8 has finished clamping and cutting the raw material W2.

[0090] The determination element 23 performs a determination for poor clamping of the collet 48 based on at least one of the processing time point information stored in the processing time point information storage unit 211 and the first clamping force history information stored in the first clamping force information storage unit 212, as well as the first current clamping force information stored in the first clamping force information storage unit 212. Furthermore, the determination element 23 performs a determination for poor clamping of the second collet 81 based on at least one of the processing time point information stored in the processing time point information storage unit 211 and the second clamping force history information stored in the second clamping force information storage unit 213, as well as the second current clamping force information stored in the second clamping force information storage unit 213. The actions of these determinations are explained in detail below using flowcharts.

[0091] The correction value rewriting element 24 rewrites the movement correction value stored in the movement correction value storage unit 214 when a predetermined condition is met. This predetermined condition refers to the following situation: the determination element 23 determines that the clamping force in the second current clamping force information is outside a predetermined range and the change in the clamping force in the second current clamping force information relative to the clamping force in the second clamping force history information does not exceed a predetermined threshold. Details regarding this predetermined condition will be provided below. Figure 8 and Figure 9 Further explanation.

[0092] Figure 5 and Figure 6 It means to use Figure 1 The flowchart shows the first machining action of the first spindle. The actions shown in these flowcharts are performed under the control of the control device 2. Furthermore, Figure 7 This is a diagram showing an example of the clamping force of each clamping action of the first spindle 4 from the initial machining action to the final machining action.

[0093] Before starting machining operations, the operator of NC lathe 1 performs preparatory work such as adjusting the various components of NC lathe 1. Furthermore, after selecting the NC program to be executed and specifying the number of products to be machined (cycle number) using the operation unit 11, the operator inputs the machining start command. Thus, NC lathe 1 begins continuous machining, that is, it repeatedly executes machining operations according to the selected NC program a number of times corresponding to the number of products. In addition, the description of the machining operations follows the same sequence as the actual machining operations performed, describing the first machining operation first, followed by the second machining operation.

[0094] like Figure 5As shown, after the first processing operation begins, the control device 2 determines whether the length of the raw material W1 is greater than or equal to the length of the manufactured product (step S11). When the length of the raw material W1 is shorter than the length of the manufactured product (no in step S11), the control device 2 issues a command to the feeder 10 and performs the aforementioned raw material W1 replacement operation (step S12).

[0095] When the length of raw material W1 exceeds the length of the manufactured product (yes in step S11) or after the replacement of raw material W1 in step S12 is completed, the control device 2 reads the manufacturing count counter set in counter 215 to determine whether the processing of the specified number of products has been completed (step S13). The manufacturing count counter is zero in the initial processing action and increments each time a processing action is completed. When the processing of the specified number of products is completed (yes in step S13), the first processing action ends.

[0096] When it is determined that the processing of the specified number of products has not been completed (no in step S13), the control device 2 saves information indicating whether the current processing action is the initial processing action and information indicating whether it is the processing action after the replacement of raw material W1 and the supply of new raw material W1 to the first spindle 4 to the processing time point information storage unit 211 (step S14).

[0097] In step S14, when the manufacturing count counter is zero, the control device 2 stores an initial flag indicating that the current processing action is the first processing action in the processing time point information storage unit 211. When the manufacturing count counter is non-zero, the initial flag is erased from the processing time point information storage unit 211. Alternatively, other information that can distinguish whether the current processing action is the first processing action, such as the value of the manufacturing count counter itself, can be stored instead of the initial flag. Furthermore, when the control device 2 determines in step S11 that the length of the raw material W1 is shorter than the length of the manufacturable product, it stores a replacement flag in the processing time point information storage unit 211. When it determines that the length of the raw material W1 is greater than or equal to the manufacturable length, it erases the replacement flag. Alternatively, other information that can distinguish whether the current processing action is after the new raw material W1 has been re-supplied to the first spindle 4, such as whether step S12 has been executed in the current cycle, can be stored instead of the replacement flag.

[0098] Next, the NC lathe 1 executes the clamping action of the first spindle 4 according to the clamping instructions of the NC program (step S15). In this step S15, the clamping force output element 22 outputs the clamping force of the collet chuck 48 on the raw material W1 based on the strain of the shift lever 33 detected by the strain detection element 333. Moreover, the clamping force output by the clamping force output element 22 is stored in the first clamping force information storage unit 212 in association with the information of the time it was stored. The clamping force information stored at this time becomes the first current clamping force information.

[0099] After the clamping action is completed, the determination element 23 determines whether the clamping force in the first current clamping force information saved by the first clamping force information storage unit 212 is outside the specified range and whether it is outside the continuous processing range (step S16). For example... Figure 7 As shown, the upper limit of the continuous machining range is greater than the specified range, and the lower limit is less than the specified range. Furthermore, these specified ranges and continuous machining ranges are set by the manufacturer of the NC lathe 1, but can also be changed through operator input. The specified range is the range within which machining operations can continue without problems. A range outside the specified range but within the continuous machining range is a range where a warning will be issued, but machining operations can continue. Moreover, a range outside the continuous machining range is a range where machining operations will be interrupted. Alternatively, the continuous machining range can be made consistent with the specified range. When it is determined that the clamping force in the first current clamping force information is not outside the specified range (within the specified range) (no in step S16), the process proceeds to step S21, described later.

[0100] When the clamping force in the first current clamping force information is outside the specified range (yes in step S16), the determination element 23 reads the intention indicating whether the initial flag is saved in the processing time point information storage unit 211, and determines whether the current processing action is the first processing action (step S17). If the determination element 23 has saved the initial flag in the processing time point information storage unit 211, it determines that the current processing action is the first processing action; if the initial flag is not saved in the processing time point information storage unit 211, it determines that it is a processing action from the second time onwards.

[0101] When the initial machining operation is initiated (yes in step S17), the determination element 23 determines that a clamping malfunction is caused by a preparation error, and displays this intention on the display unit 12. Furthermore, in step S16, if it is determined that the clamping force in the first current clamping force information is outside the continuous machining range, the control device 2 stops the NC lathe 1 due to an error. On the other hand, in step S16, if it is determined that the clamping force in the first current clamping force information is outside the specified range but within the continuous machining range, the display unit 12 displays that a clamping malfunction is caused by a preparation error, and proceeds to step S21 described later.

[0102] When the processing action is the second or subsequent processing action (no in step S17), the determination element 23 reads whether the processing time point information storage unit 211 has saved the intention of the changed flag, and determines whether the current processing action is the processing action that just happened after the raw material W1 was re-supplied to the first spindle 4 (step S18). That is, if the determination element 23 has saved the changed flag in the processing time point information storage unit 211, it determines that the current processing action is the processing action that just happened after the feeder 10 re-supplied the raw material W1 to the first spindle 4; if the processing time point information storage unit 211 has not saved the changed flag, it determines that it is not the processing action that just happened after the supply.

[0103] When the processing operation has just resumed after the raw material W1 has been resupplyed (yes in step S18), the determination element 23 determines that the clamping failure is caused by the defective diameter of the supplied raw material W1, and displays this instruction on the display unit 12. Additionally, as... Figure 7 As illustrated, the supply of raw material W1 is executed at the point in time when raw material W1 becomes too short after multiple products have been manufactured. Figure 7 The example shown illustrates the supply of raw material W1 for every 12 products manufactured (12 cycles). Furthermore, in step S16, when it is determined that the clamping force in the first current clamping force information is outside the continuous processing range, the control device 2 causes the NC lathe 1 to stop due to an error. On the other hand, in step S16, when it is determined that the clamping force in the first current clamping force information is outside the specified range but within the continuous processing range, the display unit 12 displays a clamping defect caused by a defective raw material diameter, and proceeds to step S21 described later.

[0104] When the processing action does not occur immediately after the resupply of raw material W1 (no in step S18), such as Figure 6 As shown, the determination element 23 determines whether the change in the clamping force in the first current clamping force information relative to the clamping force in the first clamping force history information exceeds a predetermined threshold (step S19). This threshold is set by the manufacturer of the NC lathe 1, but can also be changed through operator input. Figure 7 As shown, when using this threshold for judgment, regardless of the specified range and the continuous processing range, the difference between the clamping force in the first clamping force history information and the clamping force in the first current clamping force information is compared with the threshold.

[0105] like Figure 6As shown, when the change in clamping force in the first current clamping force information relative to the clamping force in the first clamping force history information exceeds a threshold (yes in step S19), proceed to step S22. When the change in clamping force in the first current clamping force information relative to the clamping force in the first clamping force history information does not exceed the threshold (no in step S19), the determination element 23 then determines whether the clamping force in the first current clamping force information is greater than the upper limit of the specified range (step S20).

[0106] When the clamping force in the first current clamping force information is greater than the upper limit of the specified range (yes in step S20), the determination element 23 determines that the clamping failure is caused by an unexpected reason. In this case, the control device 2 displays this instruction on the display unit 12, causing the NC lathe 1 to stop erroneously. When the clamping force in the first current clamping force information is not greater than the upper limit of the specified range (no in step S20), the determination element 23 determines that the clamping failure is caused by wear of sliding parts such as the cam surface 42a of the shifter 42 and the front end portion 43b of the jaw member 43, and displays this instruction on the display unit 12. Moreover, in step S16, when it is determined that the clamping force in the first current clamping force information is outside the continuous machining range, the control device 2 causes the NC lathe 1 to stop erroneously. On the other hand, in step S16, when it is determined that the clamping force in the first current clamping force information is outside the specified range but within the continuous machining range, the display unit 12 displays that the clamping failure is caused by wear of the sliding parts, and proceeds to step S25 described later.

[0107] If, in step S16, it is determined that the clamping force in the first current clamping force information is not outside the specified range (no in step S16), the determination element 23 determines whether the change in the clamping force in the first current clamping force information relative to the clamping force in the first clamping force history information exceeds a specified threshold (step S21). Alternatively, the determination in step S21 may be performed after steps S17 or S18 as described above.

[0108] When the change in the clamping force in the first current clamping force information relative to the clamping force in the first clamping force history information exceeds the threshold (yes in step S19 or yes in step S21), the determination element 23 then determines whether the clamping force in the first current clamping force information has increased relative to the clamping force in the first clamping force history information (step S22).

[0109] When the clamping force in the first current clamping force information does not increase relative to the clamping force in the first clamping force history information (no in step S22), the determination element 23 determines that the clamping failure is caused by an unexpected reason. In this case, the control device 2 displays the instruction on the display unit 12 and stops the NC lathe 1 from error. When the clamping force in the first current clamping force information increases relative to the clamping force in the first clamping force history information (yes in step S22), the determination element 23 reads the first removal counter set in the counter 215 and determines whether the number of removal operations described later is n times or less (step S23). This n is a value set by the operator.

[0110] When the number of removal actions exceeds n (no in step S23), the determination element 23 determines that the clamping failure is caused by an unexpected reason. In this case, the control device 2 displays the instruction on the display unit 12 and stops the NC lathe 1 from error. When the number of removal actions is less than n (yes in step S23), foreign objects such as debris may enter between the collet 48 and the raw material W1. In this case, if the foreign objects are removed, processing can continue. Therefore, the control device 2 performs the removal action (step S24).

[0111] In the removal action of step S24, after the control device 2 expands the diameter of the collet 48 to release the clamping force of the first spindle 4, it moves the first spindle 4 back and forth along the Z1 axis. This causes the first spindle 4 to move relative to the raw material W1, thus sometimes removing foreign objects that have entered the collet 48. In particular, foreign objects between the collet 48 and the raw material W1 are likely to be removed by this removal action. After step S24 is completed, the control device 2 increments the first removal counter and returns to the previous state. Figure 5 The step S15 shown is executed again from the clamping action.

[0112] When it is determined in step S21 that the change in clamping force does not exceed the specified threshold (no in step S21), such as Figure 5 As shown, the NC lathe 1 executes the manufacturing operation (step S25) of the front end portion of the product using the first spindle 4 according to the NC program. Step S25 also includes the action of transferring the cut raw material W2 to the second spindle 8. Furthermore, in step S25, the control device 2 resets the first removal count counter. Additionally, the first machining operation of step S25 is executed again via step S20 as described above. The NC lathe 1 executes these steps S11 to S25 until the product count counter reaches the specified product count.

[0113] Figure 8 and Figure 9 It means to use Figure 1The flowchart shows the second machining operation of the second spindle 8. The operations shown in these flowcharts are also executed under the control of the control device 2.

[0114] like Figure 8 As shown, similar to step S13, the control device 2 reads the manufacturing count counter set in the counter 215 to determine whether the processing of the specified number of products has been completed (step S31). When the processing of the specified number of products has been completed (yes in step S31), the second processing operation using the second spindle 8 ends. When it is determined that the processing of the specified number of products has not been completed (no in step S31), the control device 2 performs a master bar measurement (step S32). In this master bar measurement, a cylindrical master bar is clamped using the second spindle 8. This master bar is pre-set in the NC lathe 1 and is manufactured with high precision using a material that is not easily deformed by heat. The clamping force at that time is derived by the clamping force deriving element 22 based on the detection result of the second strain detection element. The clamping part of the cut raw material W2 clamped by the second spindle 8 is mostly the part processed by the first spindle 4. Therefore, the clamping force of the second spindle 8 when clamping the cut raw material W2 will affect the processing accuracy using the first spindle 4. In this regard, by using a standard bar with a known outer diameter to measure the clamping force, the machining accuracy when using the first spindle 4 is not affected, and the clamping force of the second spindle 8 can be accurately measured.

[0115] After the standard bar measurement is completed, the determination element 23 determines whether the clamping force obtained from the standard bar measurement is outside the specified range and whether it is outside the continuous machining range (step S33). Although the specified range and continuous machining range of the second spindle 8 are common to the first spindle 4, the second spindle 8 can also be set with an inherent range.

[0116] When it is determined in step S32 that the measured clamping force is outside the specified range (yes in step S33), the determination element 23 then determines whether the measured clamping force is less than the lower limit of the specified range (step S34). When the measured clamping force is greater than the lower limit of the specified range (no in step S34), the determination element 23 determines that the clamping failure is caused by an unexpected reason. In this case, the control device 2 displays the instruction on the display unit 12 and stops the NC lathe 1. When the measured clamping force is less than the lower limit of the specified range (yes in step S34), the determination element 23 determines that the clamping failure is caused by wear of sliding parts such as the cam surface 42a of the shifter 42 and the front end portion 43b of the jaw member 43, and displays the instruction on the display unit 12. Moreover, when it is determined in step S33 that the measured clamping force is outside the continuous machining range, the control device 2 stops the NC lathe 1. On the other hand, when it is determined in step S33 that the measured clamping force is outside the specified range but within the continuous processing range, the display unit 12 displays that the clamping is not good due to the wear of the sliding part, and proceeds to step S42 described later.

[0117] When it is determined that the clamping force measured in step S32 is not outside the specified range (no in step S33), the NC lathe 1 executes a clamping action to clamp the cut raw material W2, which has been processed by the first machining operation, onto the second spindle 8 (step S35). In this step S35, the clamping force output element 22 outputs the clamping force of the second collet chuck 81 on the cut raw material W2. Furthermore, the clamping force output by the clamping force output element 22 is stored in the second clamping force information storage unit 213 in association with the information of the time it was stored. The clamping force information stored at this time becomes the second current clamping force information.

[0118] After the clamping action is completed, the determination element 23 determines whether the clamping force in the second current clamping force information stored in the second clamping force information storage unit 213 is outside the specified range (step S36). In this step S36, it is determined not only whether it is outside the specified range, but also whether it is outside the continuous processing range. When it is determined that the clamping force in the second current clamping force information is not outside the specified range (within the specified range) (no in step S36), the process proceeds to step S42, which will be described later.

[0119] When step S36 is true, the determination element 23 reads the intention indicating whether the initial flag is saved in the processing time point information storage unit 211, and determines whether the current processing action is the first processing action (step S37). When it is the first processing action (true in step S37), the determination element 23 determines that the clamping failure is caused by a preparation error, and displays the intention on the display unit 12. Moreover, when it is determined in step S36 that the clamping force in the second current clamping force information is outside the continuous processing range, the control device 2 stops the NC lathe 1. On the other hand, when it is determined in step S36 that the clamping force in the second current clamping force information is outside the specified range but within the continuous processing range, the display unit 12 displays that the clamping failure is caused by a preparation error, and proceeds to step S42 described later.

[0120] When it is the second or subsequent processing operation (no in step S37), the determination element 23 is as follows. Figure 9 As shown, it is determined whether the change in the clamping force in the second current clamping force information relative to the clamping force in the second clamping force history information exceeds a predetermined threshold (step S38). This threshold is common to the first spindle 4, but an inherent threshold can also be set for the second spindle 8.

[0121] When the change in clamping force in the second current clamping force information relative to the clamping force in the second clamping force history information exceeds a threshold (yes in step S38), proceed to step S43. When the change in clamping force in the second current clamping force information relative to the clamping force in the second clamping force history information does not exceed the threshold (no in step S38), the determination element 23 then reads the reprocessing counter and determines whether the reprocessing described later has been completed (step S39). The reprocessing counter is zero during the initial processing operation and increments if reprocessing is completed. In addition, in this embodiment, the upper limit of the number of reprocessing operations is set to 1, but the upper limit can also be set to multiple times. Moreover, the upper limit is set by the manufacturer of the NC lathe 1, but it can also be changed by operator input. When the upper limit is set to multiple times, in step S39, the determination element 23 determines whether the reprocessing counter has reached the upper limit.

[0122] When the reprocessing is completed (yes in step S39), the determination element 23 then determines whether the clamping force in the second current clamping force information is less than the lower limit of the specified range (step S40). If the clamping force in the second current clamping force information is greater than the upper limit of the specified range (yes in step S40), it is considered that the reason is that the diameter of the clamping part of the cut raw material W2 held by the second spindle 8 has slightly changed and is greater than the required diameter. Therefore, the determination element 23 determines that the poor clamping is caused by thermal displacement of the first tool holder 6 or wear of the first spindle tool T1, and displays this instruction on the display unit 12, causing the NC lathe 1 to stop erroneously. Conversely, if the clamping force in the second current clamping force information is not greater than the upper limit of the specified range (no in step S40), it is considered that the reason is that the diameter of the clamping part of the cut raw material W2 held by the second spindle 8 has slightly changed and is less than the required diameter. Therefore, the determination element 23 determines that the clamping failure is caused by the thermal displacement of the first tool post 6, etc., and displays the intention on the display unit 12, causing the NC lathe 1 to stop erroneously.

[0123] When reprocessing is not completed (yes in step S39), the correction value rewriting element 24 rewrites the movement correction value of the first tool holder 6 stored in the movement correction value storage unit 214. The correction value rewriting element 24 has a formula or relational data between the clamping force and the movement correction value in the second current clamping force information, and rewrites the movement correction value so that the clamping force in the second current clamping force information becomes the center value of a specified range. At the same time, the control device 2 executes control to cut off and discard the processed portion of the raw material W1 held by the first spindle 4. Moreover, after the correction value rewriting element 24 completes the rewriting, the control device 2 uses the rewritten movement correction value to re-execute the first processing operation using the first spindle 4 from step S11. Moreover, after discarding the cut-off raw material W2 held by the second spindle 8, the control device 2 increments the reprocessing counter and re-executes the second processing operation using the second spindle 8 from step S35 (the above is step S41). In step S41, the first processing action that is re-executed from step S11 and the second processing action that is re-executed from step S35 become reprocessing actions.

[0124] If, in step S36, it is determined that the clamping force in the second current clamping force information is not outside the specified range (no in step S36), the determination element 23 determines whether the change in the clamping force in the second current clamping force information relative to the clamping force in the second clamping force history information exceeds a specified threshold (step S42). Alternatively, the determination in step S42 may be performed via step S37 or step S34 as described above.

[0125] When the change in the clamping force in the second current clamping force information relative to the clamping force in the second clamping force history information exceeds the threshold (yes in step S38 or yes in step S42), the determination element 23 then determines whether the clamping force in the second current clamping force information has increased relative to the clamping force in the second clamping force history information (step S43).

[0126] When the clamping force in the second current clamping force information does not increase relative to the clamping force in the second clamping force history information (no in step S43), the determination element 23 determines that the clamping failure is caused by an unexpected reason. In this case, the control device 2 displays the instruction on the display unit 12 and stops the NC lathe 1 from error. When the clamping force in the second current clamping force information increases relative to the clamping force in the second clamping force history information (yes in step S43), the determination element 23 reads the second removal counter set in the counter 215 and determines whether the number of removal operations described later is less than n (step S44). This n is the same as the number of removal operations of the first spindle 4, i.e., n in step S23, but a fixed value can also be set for the second spindle 8.

[0127] When the number of removal actions exceeds n (no in step S44), the determination element 23 determines that the clamping failure is caused by the breakage of the tool T1 for the first spindle. In this case, the control device 2 displays the instruction on the display unit 12 and stops the NC lathe 1 from error. When the number of removal actions is less than n (yes in step S44), foreign objects such as debris may enter between the second collet 81 and the cut raw material W2. In this case, as long as the foreign objects can be removed, processing can continue. Therefore, the control device 2 performs the removal action (step S45).

[0128] In the removal action of step S45, after the control device 2 expands the diameter of the second collet 81 to release the clamping of the second spindle 8, it causes the second coolant discharge section 91 to discharge coolant into the second spindle 8. Then, the control device 2 causes the blower of the second spindle 8 to blow air from the rear end to the front end. This removes or disperses foreign objects that have entered the second collet 81. In particular, foreign objects between the second collet 81 and the cut raw material W2 are likely to be removed by this removal action. Furthermore, in this removal action, only one of the second coolant discharge section 91 and the blower can be activated, or both can be activated simultaneously. After step S45 is completed, the control device 2 increments the second removal counter and returns to the previous state. Figure 8 The step S35 shown is executed again from the clamping action.

[0129] When it is determined in step S42 that the change in clamping force does not exceed the specified threshold (no in step S42), such as Figure 8As shown, the NC lathe 1 executes the manufacturing operation (second machining operation) of the rear end portion (cut-off end portion) of the product using the second spindle 8 according to the NC program. Step S46 also includes the ejection of the product manufactured by completing one cycle of machining. Furthermore, in step S46, the control device 2 resets the second removal count counter, causing the production count counter to increment. The NC lathe 1 executes these steps S31 to S46 until the product count counter reaches the specified product count.

[0130] According to the NC lathe 1 of this embodiment described above, the determination element 23 determines the occurrence of a clamping defect on the first spindle 4 based on at least one of the following information stored in the machining time point information storage unit 211: information on the current machining operation's timing, information on the first clamping force history, and information on the first current clamping force. Depending on the situation, the determination element 23 categorizes the types of clamping defects according to their causes. Therefore, clamping defects can be accurately determined. Similarly, the determination element 23 determines the occurrence of a clamping defect on the second spindle 8 based on at least one of the following information stored in the machining time point information storage unit 211: information on the current machining operation's timing, information on the second clamping force history, and information on the second current clamping force. Depending on the situation, the determination element 23 categorizes the types of clamping defects according to their causes. Therefore, clamping defects can be accurately determined. Furthermore, since the determination element 23 categorizes clamping defects according to their causes, it is easier for the operator to handle defects.

[0131] Furthermore, the determination element 23 compares the change in clamping force with a threshold value, thus enabling it to determine that changes in clamping force caused by the entry of a small foreign object into the collet 48 or the second collet 81 constitute clamping defects. This helps to prevent the manufacture of products damaged by such foreign objects. Moreover, this determination compares the increase or decrease of the current clamping force relative to past clamping forces; when the force increases, it is determined that clamping defects are caused by the entry of foreign objects, thus accurately identifying the type of clamping defect. Furthermore, when there is a high probability of foreign object entry, a foreign object removal operation is performed, thereby reducing the possibility of processing operations stopping due to clamping defects.

[0132] Furthermore, when the clamping force in the second current clamping force information is outside the specified range and the change in the clamping force on the second spindle 8 does not exceed the threshold, the correction value rewriting element 24 rewrites the movement correction value to a suitable value and performs reprocessing. Therefore, the machining accuracy is improved and the possibility of machining action stopping due to poor clamping is reduced.

[0133] This invention is not limited to the embodiments described above, and various modifications can be made within the scope of the claims. For example, the description of this embodiment shows an example of applying the invention to a so-called Swiss-type NC lathe 1 equipped with guide sleeve 5, but the invention can also be applied to other machine tools such as lathes or machining centers that do not have guide sleeve 5. Furthermore, the second spindle head 7, the second spindle 8, and the second tool post 9 can be omitted.

[0134] Alternatively, the constituent elements contained only in the descriptions of the above-described variations can be applied to other variations.

[0135] [Symbol Explanation]

[0136] 1: NC lathe (machine tool)

[0137] 4: First spindle (main spindle)

[0138] 8: Second spindle (main spindle)

[0139] 23: Decision Component

[0140] 48: Collet chuck (clamping part)

[0141] 81: Second collet chuck (clamping part)

[0142] W1: Raw Materials

[0143] W2: Raw materials have been cut.

Claims

1. A machine tool comprising a spindle having a clamping portion for holding rod-shaped raw materials, wherein multiple products of the same shape are manufactured by repeatedly performing machining operations on the raw materials held by the clamping portion, characterized in that... The device is equipped with a determination element that performs a determination on the spindle for poor clamping based on at least one of the following: processing time point information indicating which time point the processing action is in, clamping force history information when the clamping part clamps the raw material in the previous processing action, and clamping force information when the clamping part clamps the raw material in the current processing action, i.e., current clamping force information.

2. The machine tool according to claim 1, characterized in that, When the processing time information is information representing the initial processing action, if the clamping force in the current clamping force information is outside the specified range, the determination element determines that the poor clamping is caused by a mistake in the preparation work.

3. The machine tool according to claim 1, characterized in that, A feeder is connected to the spindle, which stores multiple raw materials and sequentially supplies the stored raw materials to the spindle. When the processing time information indicates the processing action after the feeder has just re-supplied the raw material to the spindle, if the clamping force in the current clamping force information is outside the specified range, the determination element determines that the diameter of the raw material supplied by the feeder is defective, resulting in poor clamping.

4. The machine tool according to claim 1, characterized in that, When the change in the clamping force in the current clamping force information relative to the clamping force in the clamping force history information exceeds a threshold, the determination element determines that a clamping failure has occurred.

5. The machine tool according to claim 4, characterized in that, When the change exceeds the threshold, the determination element classifies the type of clamping failure based on whether the clamping force in the current clamping force information increases or decreases relative to the clamping force in the clamping force history information.

6. The machine tool according to claim 4, characterized in that, The device includes a control unit that performs a removal action to remove foreign objects that have entered the clamping part when the change exceeds the threshold and the clamping force in the current clamping force information increases relative to the clamping force in the clamping force history information.

7. The machine tool according to claim 1, characterized in that, The determination element classifies the types of clamping defects based on a combination of whether the clamping force in the current clamping force information is outside the specified range and whether the change in the clamping force in the current clamping force information relative to the clamping force in the clamping force history information exceeds a threshold.

8. The machine tool according to claim 1, characterized in that, have: A tool holder, on which a tool for processing the raw material is mounted, and which moves together with the tool; The storage element stores the movement correction value used to correct the specified movement position specified in the machining program; and The correction value rewriting element rewrites the shift correction value stored in the storage element; When the determination element determines that the clamping force in the current clamping force information is outside the specified range and the change in the clamping force in the current clamping force information relative to the clamping force in the clamping force history information does not exceed a threshold, the correction value rewriting element rewrites the movement correction value stored in the storage element.

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