MACHINE TOOL AND METHOD OF MACHINING A WORKPIECE

A machine tool capable of preventing production of a defective product. The processing unit determines whether the workpiece exists in the predetermined area. In the event that the workpiece exist in the area, the processing unit execute the top cut process. In the event that the workpiece does not exist in the area, the processing unit determines that the workpiece is in the abnormal position.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority of Japanese Patent Application No. 2022-096663 filed on Jun. 15, 2022. The contents of this application are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

The present invention relates to a machine tool and a method of machining a workpiece.

Japanese Unexamined Patent Application Publications No. 2021-53713 discloses an NC (numerically control) lathe provided with a bar feeder capable of supplying a bar material or a workpiece to a spindle of the lathe. Machining accuracy of the workpiece depends on positioning accuracy of the tip or the end of the workpiece.

Conventionally, the end of every brand new workpiece supplied to the spindle is cut off with a cut-off tool (an operation called “top-cut”) to position the end surface of the workpiece with precision.

SUMMARY OF THE INVENTION

When a supply error occurs, cutting off the end of the workpiece will fail, thus deteriorating positioning accuracy of the end surface of the workpiece.

The present invention provides a machine tool capable of solving the problem.

1. A machine tool includes a spindle capable of rotating a bar workpiece around its axis; a cutter capable of cutting the workpiece at a surface perpendicular to the axis; a sensor capable of detecting an object existing in an area where the cutter is located to cut the workpiece; and a controller adapted to execute an abnormality detection process prior to a top cut process of the workpiece. The abnormality detection process includes an abnormality determination process capable of determining that the object does not exist in the area according to a detection value of the sensor and thereby determining that the machine tool is not ready for the top cut process.

The top cut process can be executed only in the event that the workpiece exists in the predetermined area. The controller may determine, prior to the top cut process, whether the workpiece exists in the area in the abnormality detection process according to a detection value of the sensor. If abnormality is detected, the controller may stop the top cut process happening, thus preventing production of a defective product.

The “prior to the top cut process” may include “during the top cut process”.

2. In the machine tool according to 1 as described above, the controller is adapted to execute a retry process in the event that the abnormality detection process reveals occurrence of abnormality. The retry process includes a process of displacing the workpiece in a predetermined direction by a predetermined amount. The predetermined direction is a direction that the workpiece approaches the area where the cutter is located to cut the workpiece. The abnormality detection process further includes another abnormality determination process capable of determining whether the object exists in the area after the retry process according to a detection value of the sensor.

The retry process can modify the position of the workpiece to an appropriate position for the top cut process. Especially during nighttime unmanned continuous operation, the retry process could allow the whole process to continue without suspension.

3. In the machine tool according to 2 as described above, the controller is adapted to execute a number of retries setting process. The number of retries setting process includes a process of receiving a user instruction of the number of retries through an interface. The number of retries is an upper limit of the number of retries of the abnormal detection process and the retry process. The controller is adapted to repeat the retry process within the upper limit until the abnormality detection process reveals no occurrence of abnormality.

The number of retries setting process allows the user to set a desired value for the number of retries.

4. In the machine tool according to 2 or 3 as described above, the controller is adapted to execute a displacement amount setting process. The displacement amount setting process includes a process of receiving a user instruction of a displacement amount of the workpiece through an interface. The retry process includes a process of displacing the workpiece by the displacement amount received in the displacement amount setting process.

The displacement amount setting process allows the user to set a desired value for the displacement amount.

5. In the machine tool according to any of 2 to 4 as described above, the controller is adapted to execute an abnormality measures process in the event that the abnormality detection process reveals occurrence of abnormality after the retry process. The abnormality measures process includes a process of outputting an alarm and shutting off a working machine comprising the cutter and the spindle.

The abnormality measures process after the retry process allows the user to be notified of abnormality and prevents execution of subsequent processes.

6. In the machine tool according to any of 1 to 5 as described above, the cutter includes a cut-off tool and a sensor capable of detecting the object existing in the area where the cut-off tool is located to cut the workpiece. The controller is adapted to execute a cut-off tool breakage detection process after a cut-off process to determine that the cut-off tool is broken in the event that the sensor detects the object exists in the area.

The sensor for use in the cut-off tool breakage detection process is available for the workpiece position abnormality detection process, thus eliminating the need for a separate sensor.

7. In the machine tool according to any of 1 to 6 as described above, the controller includes an executing apparatus and a storage apparatus. The controller is adapted to receive a machining program input by a user through an interface. The storage apparatus stores a plurality of code data. The machining program is a selective combination of the code data to instruct the executing apparatus to control a working machine comprising the cutter and the spindle. The code data includes a code for instructing the executing apparatus to execute the abnormality detection process.

Accordingly, the machining program may include the instruction for executing the abnormality detection process.

A plurality of code data may include a code for instructing the executing apparatus to execute the retry process. A plurality of code data may include a code for instructing the executing apparatus to execute the cut-off tool breakage detection process.

8. In the machine tool according to any of 1 to 7 as described above, the sensor includes a detector capable of outputting a signal according to the detection value when the detector is displaced into the area where the cutter is located to cut the workpiece.

It can be determined whether an object exists in the predetermined area according to a detection result by the sensor. In the event that it is determined that an object exists in the predetermined area, it can be then determined that the object exists in the area where the cutter is located to cut the workpiece.

Displacing the detector into the predetermined area can facilitate such determination according to an output signal from the sensor.

The abnormality detection process using the sensor can be executed prior to top-cut. The cutter may include the cut-off tool and the sensor may be provided with the detector. The sensor may output a signal according to existence of the object in the predetermined area by displacing the detector into the predetermined area. The predetermined area may be defined by a component of a first coordinate axis greater than a value of the area where the cut-off tool is located to cut the workpiece, a component of a second coordinate axis containing the value of the component of the second coordinate axis of the workpiece, and a component of a third coordinate axis containing the value of the component of the third coordinate axis of the workpiece. The first coordinate axis includes the axis of the workpiece. The component of the first coordinate axis includes a positive component in a direction that the workpiece approaches the cut-off tool. The second coordinate axis and the third coordinate axis may be perpendicular to each other and perpendicular to the first coordinate axis.

9. In the machine tool according to any of 1 to 7 as described above, the sensor includes a non-contact sensor capable of detecting the object existing in the area where the cutter is located to cut the workpiece.

10. A method of machining a workpiece including executing the processes in the machine tool of according to any of 1 to 9 as described above.

DETAILED DESCRIPTION

The embodiment is being described referring to the drawings.

[Configuration of the Machining System]

FIG.1shows the configuration of the machining system of the embodiment.

A lathe1may include a working machine10and a machining controller50. The working machine10may include an apparatus capable of cutting a bar material or a workpiece W. The working machine10may include a spindle14mounted on a bed12. The spindle14may rotate the workpiece W around an own axis as the rotation axis. The spindle14may be provided with a chuck16capable of holding the workpiece W. The spindle14may be displaced in positive and negative directions of a Z-axis shown inFIG.1. The Z-axis may be an axis containing the axis of the workpiece W inserted into the spindle14. The Z-axis may horizontally extend.

The working machine10may have a guide bush18capable of supporting the workpiece W on the positive side of the spindle14with respect to the Z-axis. The working machine10may be provided with a tool post20. The tool post20may have a turning tool capable of machining the workpiece W protruded from the guide bush18. The tool post20may be displaced in directions of a Y-axis and an X-axis shown inFIG.1. The direction of the Y-axis may be horizontal and perpendicular to the direction of the Z-axis. The direction of the X-axis may be perpendicular to the directions of the Z-axis and the Y-axis.

A bar feeder40may supply the workpiece W to the working machine10. The bar feeder40may displace the workpiece in the positive direction with respect to Z-axis to thereby insert the workpiece W into the spindle14. The bar feeder40may be provided with an actuator40aand an end-detection sensor40b. The actuator40amay push the workpiece W toward the positive direction. The end-detection sensor40bmay detect a displacement amount of the workpiece W.

A feeder controller42may operate the bar feeder40to control a supply of the workpiece W to the working machine10according to a detection result by the end-detection sensor40b.

The machining controller50may control the working machine10. The controller50may control a Z-axis coordinate of the spindle14and X-axis and Y-axis coordinates of the tool post20. The controller50may include a PU (Processing Unit)52, a ROM (Read Only Memory)54and a RAM (Random Access Memory)56. The PU52may include a software processing apparatus such as a CPU (Central Processing Unit), GPU (Graphics Processing Unit), and TPU (Tensor Processing Unit). The ROM54may include an electrically-non-rewritable memory. The RAM56may include an electrically-rewritable non-volatile memory and a storage medium such as a disk.

[Detailed Function of the Lathe]

FIG.2shows the configuration of the tool post20. The tool post20may have plural cutting tools22(1) to22(6) attached thereto. The cutting tools22(1) to22(6) may be collectively referred to as the cutting tool22. The tool22(1) may be a cut-off tool. The cut-off tool22(1) may sever the workpiece W with a cut surface thereof being perpendicular to the Z-axis.

The tool post20may be provided with a cut-off tool breakage detection apparatus30. The breakage detection apparatus30may include a detection probe32, an object34, a contact sensor36, and a resilient member38. The detection probe32and the object34may be coupled. The resilient member38may push the object34to the contact sensor36. The contact sensor36may output a signal according to the contact state of the object34. The contact sensor36may include a differential transformer sensor, an optical scale sensor, and a magnet scale sensor.

FIG.3AandFIG.3Beach shows a breakage detection of the cut-off tool22(1).FIG.3Ashows the state of normal cut-off completion. The end of the workpiece W may be in a position of a smaller Z-coordinate than the cut-off tool22(1). The probe32does not touch the workpiece W when the tool post20is displaced in the positive direction of the Y axis.

FIG.3Bshows the state of abnormal cut-off completion because of breakage of the cut-off tool22(1). Displacing the tool post20in the positive direction of the Y-axis would bring the probe32to touch the workpiece W and thereby apply force to the probe32in the negative direction of the Y-axis, thus bringing the object34away from the contact sensor36against resilient force of the resilient member38.

The contact sensor36may thereby detect a contact state with respect to the object34according to breakage of the cut-off tool22(1).

FIG.4shows a flowchart of the cut-off tool breakage detection code to be executed following execution of the cut-off. The cut-off tool breakage detection code described in the machining program56amay be executed by the PU52under the control program54. The flowchart shows each process by a step number beginning with a letter “S.”

First, the PU52may displace the tool post20in the positive direction of the Y-axis by a predetermined amount ΔY (S10) to bring the probe32of the breakage detection apparatus30into a predetermined area A shown inFIG.1. The Z-axis coordinate component of the predetermined area A may be a predetermined value or more. The predetermined value of the Z-axis coordinate component of the predetermined area A may be the minimum of the Z-axis coordinate component of the cut-off tool22(1). The Z-axis coordinate component of the predetermined area A may range from 2 times to 5 times or less the difference of the minimum and the maximum of the Z-axis coordinate components of the cut-off tool22(1). The Z-axis coordinate component of the predetermined area A may be 20 times or less the difference of the minimum and the maximum of the Z-axis coordinate components of the cut-off tool22(1). The Y-axis coordinate component of the predetermined area A may contain a value of the Y-axis coordinate component of the axis of the workpiece W.FIG.1shows that the Y-axis coordinate component of the predetermined area A contains all the values of the Y-axis coordinate components of the workpiece W. The X-axis coordinate component of the predetermined area A may contain the value of the X-axis coordinate component of the axis of the workpiece W.FIG.1shows that the X-axis coordinate component of the predetermined area A contains all the values of the X-axis coordinate components of the workpiece W.

Then the PU52may determine whether an object exists in the predetermined area A according to the detection result of the contact sensor36(S12).FIG.3Ashows the state an object does not exist in the predetermined area A.FIG.3Bshows the state an object exists in the predetermined area A. Specifically, the PU52may determine whether an object exists in the specific portion where entry of the probe32is allowed. The Z-axis coordinate component of the specific portion of the predetermined area A may be only part of the Z-axis coordinate component of the predetermined area A. In the event that an object exists in the predetermined area (S12: YES), the PU52may determine that the cut-off tool22(1) is broken (S14). The PU52may operate a speaker64shown inFIG.1to output an alarm, thereby notifying the user of the breakage (S16). The PU52may stop the working machine10(S18), thus shutting off power supply to a spindle motor for the spindle14and to a tool post actuator for the tool post20.

The PU52may finish theFIG.4process upon completing Step S18or upon determining that an object does not exist in the predetermined area (S12: NO).

The cut-off tool22(1) may be also used to cut off the end of a fresh workpiece W just supplied from the bar feeder40for positioning purpose. Displacement amount of the workpiece W held by the chuck16can be defined with accuracy by that of the spindle14. It might be, however, difficult to precisely position the end of the fresh workpiece W just supplied from the bar feeder40with deteriorated end detection accuracy. Executing the top-cut can define with accuracy the position of the end of the fresh workpiece W. The Z-axis coordinate component of the end of the workpiece W upon completion of top-cut may be equal to a value of the Z-axis coordinate component of the cut surface by the cut-off tool22(1).

FIGS.5A,5B, and5Ccollectively show supply control of the fresh workpiece W by the bar feeder40for the purpose of top-cut.FIG.5Ashows positional relationship of the spindle14and others before the start of supply control by the bar feeder40. The Z-axis coordinate component of the spindle14may be a smaller value. The distance L2from the chuck16to the guide bush18may be previously determined. The distance L1from the end detector40bto the guide bush18may be previously determined. Thus, the feeder controller42may previously know the value of the distance L1minus the distance L2.

FIG.5Bshows the state the bar feeder40has fed the workpiece Win the positive direction of the Z-axis by a predetermined amount LL from the end detector40b. The end of the workpiece W may protrude beyond the chuck16in the positive direction of the Z-axis to be held by the chuck16.

FIG.5Cshows the state that the spindle14has been displaced in the positive direction of the Z-axis with the end of the workpiece W protruding beyond the guide bush18to enter the predetermined area A where the top-cut may be executed.

FIG.6Ais an expanded view of part ofFIG.5C. The end of the workpiece W protrudes beyond the guide bush18.

FIG.6Bshows the state of cut-off completion. Displacing the tool post20in the negative direction of the X-axis may enable the cut-off tool22(1) to sever the workpiece W.FIG.6Bshows a cut piece Wa severed from the workpiece W. The Z-axis coordinate component of the end of the workpiece W may be equal to the minimum of the Z-axis coordinate components of the cut-off tool22(1).

The top-cut above described could fail if the Z-axis coordinate component of the end of the workpiece W equals the Z-axis coordinate component of the cut-off tool22(1) or lower. The embodiment provides a code that determines whether an abnormal condition exists prior to commencing cut-off.

[Workpiece Position Abnormality Detection Code for Top-Cut]

FIG.7shows a flowchart of the workpiece position abnormality detection code included in the code data group54b. The workpiece position abnormality detection code may determine whether the workpiece W is in the normal position before commencing top-cut. The workpiece position abnormality detection code described in the machining program56amay be executed by the PU52under the control program54a.

First, the PU52may displace the tool post20in the positive direction of the Y-axis by a predetermined amount ΔY (S20). Then, the PU52may determine whether an object exists in the predetermined area A by receiving a signal from the contact sensor36(S22). In the event that there exists no object in the predetermined area A (S22: NO), the PU52may determine that the workpiece W is in the abnormal position (S24). In other words, the PU52may determine that executing top-cut could end with an abnormal result.

Then the PU52may increment a retry counter C by 1 (one) (S26). The retry counter C may be 0 (zero) by default. The PU52may then determine whether the retry counter C equals the number of retries Cth or more (S28). In the event that the retry counter C is less than the number of retries Cth (S28: NO), the PU52may displace the tool post20in the negative direction of the Y-axis by a predetermined amount ΔY (S30) to bring the probe32out of the predetermined area A.

The PU52may then displace the workpiece W in the positive direction of the Z-axis by a predetermined amount ΔZ (S32) and then resume the process from Step S20. In the event that the retry counter C equals the number of retries Cth or more (S28: YES), the PU52may operate the speaker64to output an alarm, thereby notifying the user of abnormality (S34). The PU52may stop the working machine10(S36), thus shutting off power supply to the spindle motor and to the displacement actuator for the spindle14and the tool post20.

The PU52may finish theFIG.7process upon completing Step S36or upon determining that an object exists in the predetermined area (S22: YES). The number of retries Cth and the displacement amount ΔZ may be predetermined by a user.

FIG.8is a flowchart of a parameters setting process of the number of retries Cth and the displacement amount ΔZ. The process may be executed by the PU52under the control program54each time, for example, predetermined requirements are satisfied.

First, the PU52may determine whether an input device60has received a user instruction of the number of retries (S40). In the event that the input device60has received a user instruction of the number of retries (S40: YES), the PU52may substitute the user instruction for the number of retries Cth (S42). In the event that the input device60has received no instruction (S40: NO), the PU52may substitute the default Cth0for the number of retries Cth (S44).

Upon completion of S42or S44, the PU52may determine whether the input device60has received a user instruction of the displacement amount ΔZ for the workpiece W (S46). In the event that the input device60has received a user instruction of the displacement amount ΔZ (S46: YES), the PU52may substitute the user instruction for the displacement amount ΔZ (S48). In the event that the input device60has received no instruction (S46: NO), the PU52may substitute the default ΔZ for the displacement amount ΔZ (S50).

The PU52may finish theFIG.8process upon completion of S48or S50.

An Example of Flowchart of the Machining Program of the Embodiment

FIG.9is a flowchart of the machining process in accordance with the machining program56aincorporating the workpiece position abnormality detection code shown inFIG.7. The machining program56amay be executed by the PU52under the control program54a.

First, the PU52may instruct the feeder controller42to control the bar feeder40to feed the workpiece W to the working machine10(S60). The PU52may then instruct the chuck16to hold the workpiece W (S62) as shown inFIG.5B. The PU52may then displace the spindle14in the positive direction of the Z-axis by a predetermined amount (S64) as shown inFIG.5C.

The PU52may then execute theFIG.7process. In the event that there exists an object in the predetermined area (S22: YES), the PU52may execute top-cut (S66) and then continuously operate the working machine10(S68) in accordance with the machining program56ato produce plural products from the single workpiece W. The process may include repeated series of operations; machining the end of the workpiece W and cutting off the workpiece W whose cut surface being distant from the end of the workpiece by a predetermined length. The repeated series of operations may desirably include the cut-off tool breakage detection process (FIG.4) to be executed after each and every cutting off.

The PU52may finish theFIG.9process upon completion of S68or S36.

An Example of Flowchart of the Machining Program of the Embodiment

FIG.10is a flowchart of the machining process in accordance with the machining program56anot incorporating the workpiece position abnormality detection code shown inFIG.7. The machining program56amay be executed by the PU52under the control program54a.FIG.10shows the same step numbers asFIG.9for the same processes.

The PU52may execute S60to S64and then finish theFIG.10process upon completion of S66and S68. If the Z-axis coordinate component of the end of the workpiece W is smaller than the Z-axis coordinate component of the cut-off tool22(1) before commencing S66, cutting off the workpiece W with the cut-off tool22(1) would fail, thus producing a defective product whose axial length is shorter to be output first among the products continuously output in S68.

The effect of the embodiment is being described. The code data group54bstored in the ROM54of the controller50may include the workpiece position abnormality detection code defining theFIG.7process, which allows the user of the working machine10to describe the machining program56aincluding theFIG.7process as shown inFIG.9. The workpiece position abnormality detection code may determine whether the end of the workpiece W is in the normal position within the predetermined area A before commencing top-cut. Such machining program56acould prevent a defective product first produced among plural products made of the single workpiece W regardless of supply accuracy of the bar feeder40.

The elements described in the embodiment correspond to the elements described in the summary as follows: The machine tool may correspond to the lathe1. The cutting unit may correspond to the cutting tool22. The sensor may correspond to the cut-off tool breakage detection apparatus30. The abnormality detection process may correspond to the S20to S24steps. The retry process may correspond to the S30and S32steps. The predetermined direction may correspond to the positive direction of the Z-axis. Setting the number of retries may correspond to the S40and S42steps. Setting the displacement amount may correspond to the S46and S48steps. The abnormality measures may correspond to the S34and S36steps. The cut-off tool breakage detection process may correspond to the S10to S14steps. The executing unit may correspond to the PU52. The storage apparatus may correspond to the ROM54. The detector may correspond to the probe32. The sensor may correspond to the non-contact sensor80.

Modified Embodiments: The invention can be implemented in a modified embodiment. The embodiment and the modified embodiment can be combined as far as they are not technically contradictory to each other.

The maximum number of retries Cth may be set by the user but not necessarily. The parameter setting process may be optional.

The displacement amount “+ΔZ” of the workpiece W may be set by the user but not necessarily. The parameter setting process may be optional.

The retry process may be optional.

[Setting Number of Retries]

In the event that no instruction is given by the user (S40:FIG.8), the PU52may substitute the default Cth0for the number of retries Cth but not necessarily. Only the input by the user may trigger the retry process.

In the event that no instruction is given by the user (S46:FIG.8), the PU52may substitute the default ΔZ0for the displacement amount ΔZ but not necessarily. Only the input by the user may trigger the retry process.

The abnormality measures taken in the event of workpiece position abnormality may include both of the S34and S36steps but not necessarily. One of the steps may be optional.

The workpiece position abnormality detection code may contain subsets of the codes; a code for giving instructions for executing the S20to S24steps, a code for giving instructions for executing the S26to S32steps, and a code for giving instructions for executing the S34to S36steps. The user can separately select at least one of the codes; the code for giving instructions for executing the workpiece position abnormality detection, the code for giving instructions for executing the retry process, and the code for giving instructions for executing the abnormality measures. The code for giving instructions for executing the abnormality measures may be common to, for example, a code for giving instructions for executing the abnormality measures taken in the event of cut-off tool breakage as described below.

For example, the code for giving instructions for executing the workpiece position abnormality detection may be included in the code for giving instructions for executing top-cut.

The cut-off tool breakage detection code may contain subsets of the codes; a code for giving instructions for executing the S10to S14steps and a code for giving instructions for executing the S16to S18steps. The user can separately select at least one of the codes; the code for giving instructions for executing the cut-off tool breakage detection and the code for giving instructions for executing the abnormality measures.

For example, the code for giving instructions for executing the cut-off tool breakage detection may be included in the code for giving instructions for the cut-off tool.

The code data may include both of the cut-off tool breakage detection code or the subsets of the codes and the workpiece position abnormality detection code or the subsets of the codes but not necessarily. For example, the cut-off tool breakage detection code may be optional if a sensor is specially provided to detect workpiece position abnormality as described below.

The controller may execute the machining program written by a combination of the code data but not necessarily. The controller may be a control apparatus specially designed to execute a series of predetermined processes to machine the workpiece W. The workpiece position abnormality detection process may be still available prior to top-cut.

The detector may be the probe32shown inFIG.2but not necessarily. A cylinder70inFIG.11AandFIG.11Bmay be available.FIG.11Ashows the state the workpiece W exists in the predetermined area A.FIG.11Bshows the state the workpiece W does not exist in the predetermined area A. The detector using the cylinder70may be a lead switch or a magnet-type cylinder position detector.

The sensor capable of detecting an object in the predetermined area A may be the cut-off tool breakage detection apparatus30but not necessarily. An apparatus having the same structure as that of the breakage detection apparatus30may be provided as an apparatus for use in the workpiece position abnormality detection prior to top-cut.

The sensor capable of detecting an object in the predetermined area A may be the contact sensor bringing the detector into the area to detect contact with the object, but not necessarily. A non-contact sensor80inFIG.12may be available. The non-contact sensor80arranged outside the predetermined area A could detect the workpiece W in the area at 6 intervals between the sensor80and the workpiece W.

The non-contact sensor80may be provided with a sensor coil. High frequency magnetic flux across the sensor coil would cause an occurrence of overcurrent in the workpiece W. The magnitude of overcurrent depends on the intervals between the sensor coil and the workpiece W. Sensor coil impedance is variable on the magnitude of overcurrent. Detection of impedance could therefore reveal the position of the workpiece W, thus determine whether the workpiece W exists in the predetermined area A. The non-contact sensor80may be the sensor as described above but not necessarily. The non-contact sensor may include a laser displacement gauge and a proximity sensor.

The sensor may be mounted on the tool post20but not necessarily. The sensor capable of detecting an object in the predetermined area A may include a sensor capable of detecting a load applied to the cut-off tool22(1) during top-cut. Such sensor may detect a load applied to the tool post20during displacement thereof. The load applied to the tool post20may rely on motor current of the motor that controls the displacement speed of the tool post20. The load applied to the tool post20may rely on the displacement speed and the motor current if a predetermined voltage is applied to the motor to displace the tool post20. The sensor may include a sensor capable of detecting torque transmission between the spindle14and a back spindle in contact with the end of the workpiece W to determine that the workpiece W is in the normal position.

The cutting unit may be the cutting tool22but not necessarily. A laser cutter90inFIG.13may be also available. The laser cutter90may include a laser nozzle92, a condenser94, and an oscillator96. Electromagnetic wave of predetermined frequency from the oscillator96may be transmitted to the condenser94and then output as laser beam Le from the laser nozzle92. A water jet cutter100inFIG.14may be also available. The water jet cutter100may include a water jet nozzle102, a water jet head104, and a high pressure pump106. High pressure liquid from the high pressure pump106may be output toward the workpiece W from the water jet nozzle102through the water jet head104.

The executing apparatus may be an apparatus capable of executing software processes but not necessarily. The executing apparatus may be provided with a specially designed hardware circuit such as ASIC (Application Specific Integrated Circuit) capable of executing at least part of the processes. The executing apparatus may necessarily include at least one of the configurations; (a) a processing circuit provided with a processor capable of executing all the processes in accordance with a program and a program storing device such as a memory, (b) a processing circuit provided with a processor capable of executing part of the processes in accordance with a program, a program storing device, and a specially designed hardware circuit capable of executing the other of the processes, and (c) a processing circuit provided with a specially designed hardware circuit capable of executing all the processes.

One or more software executing apparatuses may be provided. One or more specially designed hardware circuits may be provided.

The feeder controller42and the machining controller50may be separately provided but not necessarily. They may be integrated.

The storage apparatus for the control program54aand the storage apparatus for the code data group54bmay be the same but not necessarily. The storage apparatus for the control program54aand the code data group54band the storage apparatus for the machining program56amay be separate but not necessarily.