JP2008055523A - Machine tool and foreign matter catch determination method of machine tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a machine tool and a foreign matter catch determination method of the machine tool capable of preventing an erroneous determination of the catching of foreign matter between a tool holder and a main spindle member. <P>SOLUTION: This machine tool detachably retains the tool holder 10 mounted with a cutting tool for executing a cutting process for a workpiece, to the main spindle member 20 and rotates the tool holder 10 mounted with the cutting tool by rotating the main spindle member 20 to cut the workpiece; and is provided with an air supply device 70 exhausting air, an air supply passage 31 provided in a main spindle housing 30, an air supply passage 23 provided in the main spindle member, a whistle 50 emitting acoustic waves with the passing of the air provided in the air supply passage 23, and a control device 80 determining the catch of the foreign matter in the contact face between the main spindle member 20 and the tool holder 10 based on the acoustic waves emitted by the whistle 50. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a machine tool used for cutting a workpiece and a foreign object pinching determination method for a machine tool.

  Currently, there is a machine tool that holds a tool holder on which a cutting tool for cutting a workpiece is mounted in a holding hole so as to be detachable (replaceable).

  In such a machine tool, a necessary cutting tool is selected from a wide variety of cutting tools prepared in advance, and the selected cutting tool is mounted on the holding hole of the spindle member to process the workpiece. At this time, in order to maintain the processing accuracy well or to improve the processing accuracy, it is required to accurately mount the tool holder on which the cutting tool is mounted in the holding hole. For that purpose, when attaching the tool holder to the holding hole, it is very important not to insert foreign matter into the contact surface between the tool holder and the holding hole.

  However, when the machine tool is attached to the tool holder or the like with foreign matter such as cutting chips or chips generated during the processing of the workpiece, and the tool holder is attached to the holding hole, the tool holder is in contact with the holding hole. The foreign material may be caught in the surface. When the machine tool is operated in such a state, the rotation axis of the tool holder and the main shaft member deviates from the original correct rotation axis. If the workpiece is processed while the rotation axis of the tool holder and the main shaft member deviates from the correct rotation axis, the accuracy of the finished dimension of the workpiece is lowered.

  In view of this, a machine tool having a function of detecting foreign object pinching on the contact surface between the tool holder and the holding hole has been proposed. For example, in the machine tool disclosed in Patent Document 1, a linear scale is installed, and the retracted position of the tool holder is measured with the linear scale. In other words, when a foreign object is caught in the contact surface between the tool holder and the holding hole, it is detected that the foreign object is caught in the contact surface by utilizing the fact that the tool holder does not reach the specified position. is there.

In the machine tool disclosed in Patent Document 2, a gap sensor is installed, and the amount of deflection of the rotating shaft when the tool holder and the holding hole rotate is measured by the gap sensor. That is, when a foreign object is caught in the contact surface between the tool holder and the holding hole, the fact that the foreign material is caught in the contact surface is detected by utilizing the swing of the rotation axis of the tool holder and the spindle member. is there.
JP-A-5-309548 Japanese Patent Laid-Open No. 2000-5907

  However, in the machine tool disclosed in Patent Document 1, the linear scale detects thermal expansion of a tool holder, a holding hole, a pull stud, and the like due to heat generated by operation of peripheral devices and peripheral members such as a drive motor and a coil spring. In other words, it may be erroneously determined that a foreign object is caught even though no foreign object is caught in the contact surface between the tool holder and the holding hole.

  Further, in the machine tool disclosed in Patent Document 2, the gap sensor is covered with cutting scraps and chips generated as the workpiece is processed, and the accuracy of detecting the amount of deflection of the rotating shaft of the gap sensor is reduced. There are things to do.

  Therefore, as shown in FIG. 6, it is conceivable to detect the trapping of foreign matter on the contact surface between the tool holder and the holding hole with air. The machine tool shown in FIG. 6 has a holding hole 21 for holding the tool holder 10 and is rotated by a driving device such as an electric motor and a spindle member 220 between the spindle member 220 and the spindle member 220, and rotates the spindle member 20. The main shaft housing 30 is supported, and an air supply device 70, a control device 80, and a pressure sensor 90 that detect foreign object pinching are included.

  Further, the spindle member 220 and the spindle housing 30 are supplied with air supply passages 23 and 31 for supplying air discharged from the air supply device 70 via the air supply passage 71 to the contact surface between the tool holder 10 and the spindle member 220. Is provided. Further, an O-ring 32 for preventing air leakage is provided between the main shaft member 220 and the main shaft housing 30 around the air supply paths 23 and 31.

  The tool holder 10 is pulled in the direction of the main shaft member 220 (the left side in the drawing) by a tension device (such as a hydraulic cylinder or a draw bar) not shown, and a tensile pressure of several hundred kilograms or more is applied. Therefore, when no foreign matter is sandwiched between the tool holder 10 and the spindle member 220, the tool holder 10 includes the tapered portion 11 of the tool holder 10, the wall surface 21 a of the spindle member 220, the protruding portion 12 of the tool holder 10, and the spindle member 220. Is held in the holding hole 21 in a state in which the side surfaces 22 of the two are in close contact with each other.

  On the other hand, when a foreign object is sandwiched between the tool holder 10 and the spindle member 220, the tapered portion 11 of the tool holder 10, the wall surface 21 a of the spindle member 220, the protruding portion 12 of the tool holder 10, and the side surface 22 of the spindle member 220 A gap is formed between the two. Thus, when a clearance gap arises, the air discharged | emitted from the air supply apparatus 70 leaks from a clearance gap, and the air pressure in the air supply paths 23, 31, and 71 will change.

  When determining the foreign object pinching, the foreign object pinching is determined based on whether or not the air leaks and the air pressure changes. That is, the air supply device 70 discharges air based on an instruction from the control device 80, and the pressure sensor 90 detects the air pressure in the air supply path 71. The control device 80 determines whether foreign matter is caught between the tool holder 10 and the main shaft member 220 based on the air pressure value (pressure signal) detected by the pressure sensor 90.

  However, in the machine tool shown in FIG. 6, the spindle housing 30 supports the spindle member 220 in a rotatable manner, so that the contact surface between the O-ring 32 and the spindle member 220 and the spindle housing 30 is scraped. Therefore, a gap is generated between the main shaft member 220 and the main shaft housing 30, and air may leak from between the main shaft member 220 and the main shaft housing 30. When air leaks from between the main shaft member 220 and the main shaft housing 30 in this way, the air pressure value detected by the pressure sensor 90 changes (decreases), and foreign matter is present between the tool holder 10 and the main shaft member 220. There is a possibility of misjudgment that the is inserted.

  The present invention has been made in view of the above problems, and provides a machine tool and a foreign object pinching determination method for a machine tool that can prevent erroneous determination of foreign object pinching determination between a tool holder and a spindle member. For the purpose.

  In order to achieve the above object, a machine tool according to claim 1, wherein a spindle member that is rotatably supported by a spindle housing is held in a holding hole in a state in which a tool holder on which a cutting tool is mounted is detachably attached. Is a machine tool for processing a workpiece by rotating it with a rotation drive means, and is an air supply means for discharging air, and air discharged from the air supply means provided in the spindle housing is passed to the spindle member side A first air supply path, a second air supply path that is provided in the main shaft member and exhausts air discharged from the first air supply path through the holding hole, and a second air supply path that is provided in the second air supply path for the passage of air. A sound source that generates sound waves and a determination unit that determines whether the foreign material is caught on the contact surface between the spindle member and the tool holder by the sound waves generated by the sound source. The one in which the features.

  By doing in this way, when a foreign object is caught in the contact surface between the spindle member and the tool holder, the sound wave generation source generates sound waves, so that air leaks between the spindle member and the spindle housing. Even in this case, it is possible to determine whether the foreign object is caught between the tool holder and the main shaft member without erroneous determination.

  Further, as shown in claim 2 and claim 3, the sound wave generation source may be separate from the main shaft member, or may be formed integrally with the main shaft member.

  According to a fourth aspect of the present invention, the air supply device may change the air flow rate of the discharged air so that the air flow rate is plural times in the operating region of the sound wave generation source. In this way, even when the operating region of the sound wave generation source, that is, the range of the air flow rate for the sound wave generation source to generate sound waves is narrow, the number of sound wave generations can be increased, The accuracy of pinching determination can be improved.

  Further, in order to achieve the above object, the foreign object pinching determination method for a machine tool according to claim 5 is a foreign object pinching determination method for a machine tool according to any one of claims 1 to 4, Foreign matter on the contact surface between the spindle member and the tool holder according to whether the air supply means discharges air to the contact surface between the tool holder and the spindle member, and whether the sound wave generation source generates sound waves at the determination means. And a step of determining the pinching of.

  By doing in this way, when a foreign object is caught in the contact surface between the spindle member and the tool holder, the sound wave generation source generates sound waves, so that air leaks between the spindle member and the spindle housing. Even in this case, it is possible to determine whether the foreign object is caught between the tool holder and the main shaft member without erroneous determination.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, in each figure, the same or equivalent part is attached | subjected to the same reference number, and the description is abbreviate | omitted.

  FIG. 1 is a partial cross-sectional view showing a schematic configuration of a machine tool according to an embodiment of the present invention. FIG. 2 is an exploded view, a side view, and a plan view of the whistle in the embodiment of the present invention. FIG. 3 is a graph showing the pinching determination of the machine tool in the embodiment of the present invention.

  In the machine tool according to the present embodiment, the tool holder 10 on which a cutting tool for cutting a workpiece (workpiece) is mounted can be attached to and detached from the spindle member 20 (holding hole 21) (replaceable). By holding and rotating the spindle member 20, the tool holder 10 on which the cutting tool is mounted is rotated to cut the workpiece.

  The machine tool includes a tool holder 10 made of metal and holding a cutting tool, a spindle member 20 made of metal holding the tool holder 10, a spindle housing 30 made of metal that rotatably supports the spindle member 20, and the like. In addition, although not shown, the machine tool includes a drive mechanism such as a motor for rotating the spindle member 20 and a tension device (for pulling the tool holder 10 in the direction of the spindle member 20 (leftward in the drawing)) to closely contact the spindle member 20 ( A hydraulic cylinder, a drawbar, etc.).

  The tool holder 10 holds a cutting tool (not shown) at the tip, and includes a pull stud (not shown) at the other end. Further, the tool holder 10 is a side where a pull stud is formed, and a portion to be inserted into a holding hole 21 of the main shaft member 20 which will be described later is a tapered portion 11. A protruding portion 12 that protrudes outward from the tapered portion 11 is formed on the tool side.

  In the present embodiment, the example in which the portion inserted into the holding hole 21 of the spindle member 20 in the tool holder 10 is the tapered portion 11 has been described, but the present invention is limited to this. is not.

  The main shaft member 20 has a cylindrical shape, and a rotor (not shown) is formed on a part of the outer peripheral portion of the cylindrical shape, and a stator (not shown) is formed apart from the outer peripheral portion of the rotor. . The main shaft member 20 is rotated by a rotating magnetic field generated by the stator. The mechanism for rotating the main shaft member 20 is not limited to the one described above.

  Further, a holding hole 21 for holding the tool holder 10 so as to be detachable (replaceable) is formed at the tip of the main shaft member 20. The holding hole 21 has a shape corresponding to the outer shape of the tool holder 10. In the present embodiment, the holding hole 21 forms a tapered hole having a tapered wall surface 21 a (inner peripheral surface).

  Furthermore, the main shaft member 20 includes the above-described tensioning device (hydraulic cylinder, draw bar, etc.) and the like. The tool holder 10 has a pull stud pulled by a tension device, and a tensile pressure of several hundred kilograms or more is applied. This tensile pressure acts to pull the tool holder 10 into the holding hole 21. The tool holder 10 is held in the holding hole 21 in a state where the wall surface 21 a of the main shaft member 20 and the tapered portion 11 of the tool holder 10 and the side surface 22 of the main shaft member 20 and the protruding portion 12 of the tool holder 10 are in close contact with each other. (So-called two-sided constraint type).

  Further, the main shaft member 20 has contact air with the tool holder 10, that is, a holding hole 21, which is discharged from the air supply device 70 for determining whether foreign matter is caught between the tool holder 10 and the main shaft member 20 described later. An air supply path 23 that is a through-hole for supplying the air is provided. Further, the air supply path 23 of the main shaft member 20 is provided with a whistle 50 that is a sound wave generation source for determining whether a foreign object is caught between the tool holder 10 and the main shaft member 20. The whistle 50 generates sound waves when air passes and the air flow rate reaches a predetermined value (the operation region of the whistle 50). The whistle 50 can be attached by providing a recess corresponding to the outer shape of the whistle 50 at the opening end of the air supply passage 23 of the main shaft member 20 and press-fitting into the recess.

  Here, the whistle 50 will be described with reference to FIG. The whistle 50 includes a pipe 51 and a plate 52. FIG. 2A is a side perspective view of the pipe 51. FIG. 2B is a side perspective view of the plate 52. FIG. 2C is a side perspective view of the whistle 50 in which the pipe 51 and the plate 52 are assembled. FIG. 2D is a plan view of the whistle 50 in which the pipe 51 and the plate 52 are assembled.

  As shown in FIG. 2A, the pipe 51 includes a pipe through hole 51a at the center. Further, as shown in FIG. 2B, the plate 52 includes a plate through hole 52a that is a narrow hole sufficiently smaller than the pipe through hole 51a at the center. Then, as shown in FIGS. 2C and 2D, the plate 52 is press-fitted into the pipe through hole 51 a from the front and back of the pipe 51.

  A spindle housing 30 that rotatably supports the spindle member 20 by a bearing 40 is provided on the outer periphery of the spindle member 20. The spindle housing 30 has an air supply path 31 that is a through hole for supplying the air supply path 23 discharged from the air supply device 70 for determining whether foreign matter is caught between the tool holder 10 and the spindle member 20. It has been drilled. An O-ring 32 for preventing air leakage is provided between the main shaft member 20 and the main shaft housing 30 around the air supply paths 23 and 31. The air discharged from the air supply device 70 is supplied to the air supply path 31 via the air supply path 71.

  The sound wave detection device 60 detects sound waves in a predetermined frequency band. In the present embodiment, the sound wave detection device 60 detects sound waves generated by the whistle 50. When the sound wave detection device 60 detects the sound wave generated by the whistle 50, the sound wave detection device 60 outputs a detection signal (sound wave signal) to the control device 80.

  The air supply device 70 includes a compressor and the like. Based on an instruction (instruction signal) from the control device 80, the compressed air is contacted between the tool holder 10 and the holding hole 21 via the air supply paths 71, 31, and 23. To the surface. The control device 80 includes a CPU, a ROM, a RAM, and the like, and drives the air supply device 70 and executes a detection result from the sound wave detection device 60 by executing predetermined arithmetic processing according to a program stored in the ROM. (Sound wave signal) is used to determine whether a foreign object is caught.

  Here, a foreign object pinching determination method will be described. Whether the foreign object is caught is determined by whether or not the whistle 50 sounds, that is, whether or not the whistle 50 generates sound waves.

  First, the control device 80 outputs an instruction signal indicating that compressed air is discharged to the air supply paths 71, 31, and 23 to the air supply device 70. In response to this instruction signal, the air supply device 70 discharges compressed air to the air supply paths 71, 31, and 23 and supplies the compressed air to the contact surface between the tool holder 10 and the holding hole 21. Then, the control device 80 determines whether a foreign object is caught based on the sound wave signal from the sound wave detection device 60. As shown in FIG. 3, when the operating area of the whistle 50 is narrow, the air flow rate discharged from the air supply device 70 straddles the operating area of the whistle 50 (a plurality of air flow rates exist in the operating area of the sound wave source). For example, it is preferable to repeatedly perform air supply (ON), air stop (OFF), and the like. By doing so, even if the operating area of the whistle 50 is narrow, the number of times the whistle 50 generates sound waves increases, so that the accuracy of foreign object pinching determination can be improved.

  When no foreign object is sandwiched between the tool holder 10 and the spindle member 20, the tool holder 10 includes the tapered portion 11 of the tool holder 10, the wall surface 21 a of the spindle member 20, the protruding portion 12 of the tool holder 10, and the side surface of the spindle member 20. It is held in the holding hole 21 in a state where 22 is in close contact. Therefore, as shown by the one-dot chain line in FIG. 3, the air discharged from the air supply device 70 hardly passes through the whistle 50. Therefore, the whistle 50 does not sound (no sound wave is generated).

  On the other hand, when a foreign object is sandwiched between the tool holder 10 and the spindle member 20, the taper portion 11 of the tool holder 10, the wall surface 21a of the spindle member 20, the protruding portion 12 of the tool holder 10, and the side surface 22 of the spindle member 20 A gap is formed between the two. When a gap is generated in this way, as shown by the solid line in FIG. 3, the air discharged from the air supply device 70 passes through the whistle 50 and leaks from the gap to reach a predetermined flow rate. The whistle 50 sounds when the air flow rate reaches the operating range of the whistle 50 (generates sound waves). At this time, even if air leaks from a portion other than the gap between the tapered portion 11 of the tool holder 10 and the wall surface 21a of the main shaft member 20, and the protruding portion 12 of the tool holder 10 and the side surface 22 of the main shaft member 20. If the air passes through the whistle 50, it is possible to determine whether the foreign object is caught.

  When the sound wave detection device 60 detects the sound wave generated by the whistle 50, the sound wave detection device 60 outputs a detection signal (sound wave signal) to the control device 80. When the sound wave signal is not output from the sound wave detection device 60, the control device 80 determines that no foreign matter is sandwiched between the tool holder 10 and the main shaft member 20, and when the sound wave signal is output from the sound wave detection device 60, the tool holder It is determined that a foreign object is sandwiched between the main shaft member 20 and the main shaft member 20.

  In this way, the air supply passage 23 is provided with the whistle 50, and air is leaked from between the main shaft member 20 and the main shaft housing 30 by determining the foreign object being caught by the sound wave generated by the whistle 50. However, it is possible to determine whether the foreign object is caught between the tool holder 10 and the main shaft member 20 without erroneous determination.

  Moreover, in the above-mentioned embodiment, although the whistle 50 which is a sound wave generation source demonstrated using the example which is a main body member 20 and a different body, this invention is not limited to this. That is, the whistle that is a sound wave generation source can differentiate between the sound wave when air leaks from the gap formed between the tool holder and the main shaft member and the sound wave when air leaks from other gaps. The present invention is not particularly limited, and the object of the present invention can be achieved.

  For example, as shown in FIG. 4, as a first modification, the whistle 100 may be built in the main shaft member 200. FIG. 4 is a cross-sectional view of Modification 1 of the present invention. FIG. 4 is a drawing corresponding to an enlarged view of the vicinity of the whistle 50 of FIG. 1 in the above-described embodiment. As shown in FIG. 4, the whistle 100 is a substantially rectangular space provided partially around the air supply path 23. In addition, the formation method of the whistle 100 is not specifically limited, It can form by electrical discharge machining etc. Also by doing in this way, the sound wave when air leaks from the gap formed between the tool holder 10 and the spindle member 200 and the sound wave when air leaks from other gaps can be differentiated.

  As shown in FIG. 5, as a second modification, the whistle 110 to be built into the main shaft member 210 may have a wave shape. FIG. 5 is a cross-sectional view of Modification 2 of the present invention. FIG. 5 is a drawing corresponding to an enlarged view of the vicinity of the whistle 50 of FIG. 1 in the above-described embodiment. As shown in FIG. 5, the whistle 110 is a substantially wave-shaped space part provided partially around the air supply path 23. In addition, the formation method of the whistle 110 is not specifically limited, It can form by electrical discharge machining etc. Also by doing in this way, the sound wave when air leaks from the gap generated between the tool holder 10 and the main shaft member 210 and the sound wave when air leaks from other gaps can be differentiated.

It is a fragmentary sectional view showing a schematic structure of a machine tool in an embodiment of the invention. It is an exploded view, a side view, and a top view of a whistle in an embodiment of the present invention. It is a graph which shows the clamping determination of the machine tool in embodiment of this invention. It is sectional drawing in the modification 1 of this invention. It is sectional drawing in the modification 2 of this invention. It is a fragmentary sectional view which shows schematic structure of the machine tool in a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Tool holder, 11 Tapered part, 12 Protrusion part, 20,200,210 Main shaft member, 21 Holding hole, 21a Wall surface, 22 Side surface, 23 Air supply path, 30 Main shaft housing, 31 Air supply path, 32 O-ring, 40 Bearing 50, 100, 110 Whistle, 51 Pipe, 51a Pipe through hole, 52 Plate, 52a Plate through hole, 60 Sound wave detection device, 70 Air supply device, 80 Control device, 71, 71a, 71b Air supply passage, 80 Pressure sensor ,

Claims (5)

A tool holder on which a cutting tool is mounted is detachably held in a holding hole, and a workpiece is machined by rotating a spindle member rotatably supported by a spindle housing by a rotation driving means. A machine,
An air supply means for discharging air;
A first air supply path which is provided in the main shaft housing and allows air discharged from the air supply means to pass to the main shaft member side;
A second air supply path that is provided in the main shaft member and allows the air discharged from the first air supply path to pass through the holding hole;
A sound wave generation source that is provided in the second air supply path and generates a sound wave as the air passes;
A determination means for determining a squeezing of a foreign substance on a contact surface between the spindle member and the tool holder by a sound wave generated by the sound wave generation source;
A machine tool comprising:   The machine tool according to claim 1, wherein the sound wave generation source is separate from the main shaft member.   The machine tool according to claim 1, wherein the sound wave generation source is formed integrally with the main shaft member.   The machine tool according to any one of claims 1 to 3, wherein the air supply device changes the air flow rate of the discharged air so that the air flow rate reaches the operating region of the sound wave generation source a plurality of times. A foreign matter pinching determination method for a machine tool according to any one of claims 1 to 4,
Discharging air to the contact surface between the tool holder and the spindle member by the air supply means;
A step of determining, by the determination means, whether a foreign object is caught on a contact surface between the spindle member and the tool holder, depending on whether the sound wave generation source has generated sound waves;
A foreign matter pinching determination method for a machine tool, comprising:

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