JP2009297833A - Spindle structure of machine tool, and machine tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spindle structure of a machine tool capable of making a spindle displaceable in an axial direction to detect a tool condition, accurately and rapidly rotatable and achieving durability even at high speed rotation and high load. <P>SOLUTION: The spindle 120 includes a driving shaft 120B axially fixed to a housing 110 for accepting an input of driving force and a holding shaft 120A coupled to be axially displaceable with respect to the driving shaft 120B and to integrally rotate by a coupling means 140 for holding a machining tool or a workpiece, wherein the shafts are provided along the same shaft center. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a spindle structure of a machine tool and a machine tool provided with detection means for detecting a displacement of a spindle holding a machining tool or a workpiece.

  Conventionally, as shown in FIG. 7, a main spindle structure 500 of a machine tool is supported by a housing 510 so as to be rotationally driven, and a main spindle 520 for mounting a machining tool 560 on the housing 510 so as to be axially displaceable, and the main spindle Displacement detecting means 530 for detecting the displacement of the processing tool 560 attached to the 520 with respect to the housing 510, and detecting the state in which the processing tool 560 is in contact with the workpiece based on the displacement detected by the displacement detecting means 530 are known. (See, for example, Patent Document 1).

  The main shaft 520 detachably holds the processing tool 560 at the front end, is rotatably supported in the main shaft hole 514 of the housing 510 and is displaceable in the axial direction, and allows the detection member 531 to play freely through the thrust bearing 512. It is fitted.

  The detection member 531 protrudes to the front side of the housing 510 and has a shape bent toward the radial direction of the main shaft 520. A limit switch 533 operated by the detection member 531 is disposed below the housing 510, and the bracket 534 In addition, a rotation member 532 having a substantially right-angled shape that comes into contact with the detection member 531 and the limit switch 533 is rotatably attached to constitute a displacement detection means 530.

  When the machining tool 560 comes into contact with a workpiece (not shown) and the main shaft 520 is displaced in the right direction in the drawing, the limit switch 533 is turned ON, so that the displacement of the main shaft 520 relative to the housing 510 is detected, and machining is started. Is detected.

  On the back side of the detection member 531, a stopper 511 for preventing the movement of the main shaft 520 beyond a predetermined dimension is attached to the rear end portion of the main shaft 520 via the push 513, and the main shaft 520 is urged toward the workpiece. A spring 550 is attached between the stopper 511 and the detection member 531.

The main shaft 520 is driven to rotate by meshing with an internal gear 580 that has a gear 526 at the rear end and is driven by a drive source (not shown), and the main shaft 520 remains engaged with the gear 526. By allowing relative movement in the axial direction of 520, displacement is allowed in the axial direction of the main shaft 520.
Japanese Utility Model Publication No. 63-10910 (2nd page, FIG. 2)

  Since the main spindle structure of such a conventional machine tool is supported so as to be displaceable in the axial direction, the transmission mechanism itself that rotationally drives the main spindle needs to have a structure that allows axial displacement. It is necessary to have a bearing structure that reduces the stability of driving force transmission and allows axial displacement while receiving the force in the shaft bending direction that occurs during rotational driving. There has been a problem that accuracy and durability at the time of lowering.

  The invention according to claim 1 is a spindle that is rotatably supported by a housing, mounts a machining tool or a workpiece, and allows axial displacement of the machining tool or the workpiece with respect to the housing, and the displacement of the machining tool or the workpiece In the main spindle structure of a machine tool provided with a displacement detecting means for detecting the state and a state detecting means for detecting the state of the machining tool or workpiece based on the displacement detected by the displacement detecting means, the main shaft receives a driving force. The drive shaft and the holding shaft for holding the processing tool or workpiece are arranged on the same axis, and the drive shaft is fixed to the housing in the axial direction and can be driven to rotate. And the holding shaft is connected to the drive shaft so as to be elastically displaceable in the axial direction and so as to rotate integrally.

  According to the second aspect of the present invention, in addition to the configuration of the main spindle structure of the machine tool according to the first aspect, the drive shaft and the holding shaft are coupled by a coupling means, and the coupling means intersects the axis. The above-mentioned problem is solved by comprising a connecting pin provided in a direction to be engaged, a groove portion extending in the axial direction and engaging with the connecting pin, and a biasing means for biasing the holding shaft in a direction away from the drive shaft. It is.

  According to the third aspect of the present invention, in addition to the configuration of the main spindle structure of the machine tool described in the first or second aspect, the guide is supported in a manner that the housing is fixed and rotatable in the axial direction. The above-described problem is solved by having a cylinder and inserting the holding shaft into the guide cylinder so as to be axially displaceable and integrally rotated.

  According to the fourth aspect of the present invention, in addition to the configuration of the main spindle structure of the machine tool according to any one of the first to third aspects, the displacement detection means is integrally attached to the holding shaft. The present invention solves the above-mentioned problem by comprising a detection member that is provided and a non-contact sensor provided at a position facing the detection member of the housing.

  According to the fifth aspect of the present invention, in addition to the configuration of the spindle structure of the machine tool according to the fourth aspect, the detection member has a magnet piece at a position facing the non-contact sensor, and the non-contact The sensor is composed of a pair of Hall elements provided so as to face the vicinity of both end portions in the axial direction of the magnet piece.

  In addition to the configuration of the spindle structure of the machine tool described in claim 5, the invention according to claim 6 solves the problem by arranging a plurality of the magnet pieces at equal intervals in the circumferential direction. To do.

  According to a seventh aspect of the present invention, in addition to the configuration of the main spindle structure of the machine tool according to any one of the first to sixth aspects, the state detecting means is a machining tool mounted on the main spindle. A machining tool based on displacement information from the displacement detecting means at the machining tool mounted on the spindle or the machining start position of the workpiece at the time of machining of the workpiece by the machining or machining by the machining tool of the workpiece mounted on the spindle This problem is solved by determining the abnormality.

  The invention according to claim 8 solves the above-mentioned problem by providing the spindle structure according to any one of claims 1 to 7 in a machine tool having a spindle.

  In the main spindle structure of the machine tool according to the first aspect of the invention, since the main spindle is separated into the drive shaft and the holding shaft, and the holding shaft does not receive the force in the bending direction due to the driving force, it can be rotated at high speed with high accuracy. Since the shaft is not displaced in the axial direction, a driving force can be stably transmitted from the outside, and a bearing structure having durability even at high rotation and high load can be obtained.

  The spindle structure of the machine tool according to the second aspect of the invention has the simple structure of the connecting means in addition to the effect exerted by the spindle structure of the machine tool according to the first aspect, and rotates from the drive shaft to the holding shaft. The transmission of bending, vibration, etc. can be kept to a minimum while stably transmitting, and the holding shaft can be rotated more accurately and at high speed. Thus, the contact between the machining tool and the workpiece at the start of machining can be stably detected as a displacement.

  The main spindle structure of the machine tool according to the third aspect of the invention has the effect of the main spindle structure of the machine tool according to the first or second aspect, and a guide cylinder provided between the housing and the holding shaft. Since the holding shaft is rotatably supported integrally with the guide cylinder and is supported by sliding in the axial direction by the guide cylinder, the holding shaft can be stably supported with high accuracy even at high rotation and high load.

  The spindle structure of the machine tool of the invention according to claim 4 has the spindle and the detection member integrally fixed in addition to the effect exerted by the spindle structure of the machine tool according to any one of claims 1 to 3. Since the displacement detecting means is detected in a non-contact manner, the structure is simple and the detection accuracy can be increased.

  The main spindle structure of the machine tool according to the fifth aspect of the invention can be easily formed by using the Hall element as the displacement detecting means in addition to the effect exhibited by the main spindle structure of the machine tool according to the fourth aspect.

  The spindle structure of the machine tool according to the sixth aspect of the present invention is capable of detecting a periodic signal that changes according to the rotation state by the detecting means in addition to the effect exerted by the spindle structure of the machine tool according to the fifth aspect. Therefore, it is possible to detect the rotation unevenness of the spindle and the state of abnormal rotation.

  The spindle structure of the machine tool according to the seventh aspect of the invention can accurately detect an abnormality in the machining tool in addition to the effect exerted by the spindle structure of the machine tool according to any one of the first to fifth aspects. In addition, it is possible to prevent failures and breakage of workpieces, spindles, machine tool feeders, and the like due to machining operations with abnormal tools.

  A machine tool according to an eighth aspect of the present invention includes the spindle structure according to any one of the first to seventh aspects, so that the machine tool has a simple structure, high accuracy, and easy detection of an abnormal state. It can be a machine.

  First, as shown in FIG. 1, a main spindle structure 100 of a machine tool according to an embodiment of the present invention includes a holding shaft 120A that is supported so as to be rotatable with respect to a housing 110 and displaceable in an axial direction. A drive shaft 120B, which is also rotatably supported, has a main shaft 120 connected on the same axis by a connecting means 140, and a displacement detection means 130 for detecting the axial displacement of the holding shaft 120A with respect to the housing 110. ing.

  The housing 110 has a housing front part 110 </ b> A and a housing rear part 110 </ b> B fastened by a housing fastening bolt 113. As shown in FIG. 3, the housing 110 is provided with a fixing hole 115, and a fixing bolt 114 is inserted into the fixing hole 115 so that the housing 110 can be used as a tool post (not shown) of a machine tool. Fix it.

The housing front part 110A supports the guide tube 116 rotatably via the holding shaft bearing 112, and the guide tube 116 is positioned by the guide tube fixing nut 117 so as not to move in the axial direction on the holding shaft bearing 112. Yes.
The holding shaft 120 </ b> A has a key groove 129 provided so as to extend in the axial direction, and a key 118 provided on the guide tube 116 is fitted to rotate integrally with the guide tube 116 so as to be axially displaceable. It is loosely fitted. Further, a tool holding portion 121 (a collet chuck in the embodiment of FIG. 1) is provided at one end protruding out of the housing 110, and a connecting means 140 for connecting to the drive shaft 120B is provided at the other end in the housing 110.

The housing rear portion 110B supports the drive shaft 120B via the drive shaft bearing 111 so that the drive shaft 120B can rotate and cannot move in the axial direction.
The drive shaft 120 </ b> B is fixed at one end protruding out of the housing 110 to a gear 126 to which a driving force is transmitted from an external drive source (not shown) by a gear fixing nut 125, and the drive shaft 120 </ b> B is supported by the end face of the gear 126. Positioned in the axial direction. Further, the drive shaft 120B has a connecting means 140 with the holding shaft 120A at the other end in the housing 110.

  As shown in FIGS. 1 and 2, the connecting means 140 includes a cylindrical portion 143 provided at an end portion in the housing 110 of the drive shaft 120B so that the end portion of the holding shaft 120A is inserted, and the cylindrical portion. 143, a pin holding hole 144 provided so as to penetrate in a direction perpendicular to the axis, a groove 142 provided to extend in the axial direction at the end of the holding shaft 120A in the housing 110, and the groove 142 and a connecting pin 141 inserted through the pin holding hole 144, and the holding shaft 120A and the drive shaft 120B are configured to rotate integrally while allowing the axial displacement of the holding shaft 120B.

  The urging means 150 is configured so that the coil spring 151 provided in the cylindrical portion 143 projects the holding shaft 120A from the housing 110 via the washer 153 and the spring seat 152 with respect to the bottom of the cylindrical portion 143. It is configured by always energizing. The biasing force can be adjusted by increasing or decreasing the number of washers 153.

  On the other hand, as shown in FIGS. 1 and 3, the displacement detection means 130 includes a detection member 131 that is externally fitted and fixed so as to be displaced integrally with the holding shaft 120A in the axial direction, and a housing 110 of the detection member 131. It consists of magnet pieces 132 provided at four positions at equal intervals in the circumferential direction and non-contact sensors 133 provided at positions facing the magnet pieces 132 of the housing 110.

  The displacement of the holding shaft 120A is defined by the spacer 122 provided between the detection member 131 and the end surface of the guide tube fixing nut 117 on the projecting side, and the entry side is defined by the end surface of the holding shaft 120A and the end surface of the guide tube 116. The Further, during processing, the end surface of the holding shaft 120A and the end surface of the guide tube 116 are in close contact with each other.

As shown in FIG. 4, the non-contact sensor 133 includes a pair of Hall elements 134 and 135 provided so as to face the vicinity of both end portions in the axial direction (left and right direction in the drawing) of the magnet piece 133.
The detection signal of the displacement detection means 130 is transmitted to a state detection means provided in a control device or the like (not shown) of the machine tool.

Operation in the spindle structure 100 of the machine tool configured as described above will be described.
Prior to the start of machining, with a working tool (not shown) attached to the tool holding portion 121 of the holding shaft 120A, the biasing means 150 causes the spacer 122 and the guide tube to move in the work direction (left direction in FIG. 1) in the housing 110. It is urged to a position where the end face of the fixing nut 117 comes into close contact. At this time, the axial positional relationship between the magnet piece 133 and the Hall elements 134 and 135 is such that the magnetic field around both ends in the axial direction of the magnet piece 133 is in both the pair of Hall elements 134 and 135 as shown in FIG. As the main shaft 120 rotates, the four magnet pieces 133 at equal intervals in the circumferential direction periodically approach and leave the Hall elements 134 and 135 as the main shaft 120 rotates, and the outputs of the Hall elements 134 and 135 respectively. As a result, a signal having a waveform as shown in FIG. 5 is obtained.

  When the tool post with the housing 110 fixed is fed in the workpiece direction and the machining tool comes into contact with the workpiece, the holding shaft 120A is displaced in the axial direction with respect to the housing 110 against the biasing force of the biasing means 150.

  Only the urging force of the urging means 150 is adjusted so that the processing is not started only by pushing the holding shaft 120A. When the end surface of the holding shaft 120A and the end surface of the guide tube 116 are brought into close contact with each other, the holding shaft 120A is positioned. Processing starts. At this time, the axial positional relationship between the magnet piece 133 and the Hall elements 134 and 135 changes, and the Hall element 134 on the axial workpiece side is not affected by the magnetic field. A signal having a waveform as shown in FIG. 6 is obtained as an output.

  The holding shaft 120A is axially displaced while rotating integrally with the guide tube 116, the guide tube 116 is supported by the housing 110 via the holding shaft bearing 112, and the drive shaft 120B receives driving force via the gear 126. In order to receive the force, a force in the bending direction is also applied. However, since the rotation is transmitted to the holding shaft 120A by the connecting means 140, the tool held on the holding shaft 120A is affected by the bending and the displacement in the axial direction. High-speed rotation with high accuracy without being affected.

  Further, since the drive shaft 120B is supported by the bearing so as to be rotatable only with respect to the housing 110, the drive force is stably transmitted from the gear 126 without being affected by the displacement of the holding shaft 120A.

  Then, the displacement detection means 130 monitors the change of the respective hall elements 134 and 135 from the waveform of FIG. 5 to the waveform of FIG. 6 and detects the contact between the machining tool and the workpiece, that is, the start of machining. The state detection means can accurately specify the machining start time based on the output of the displacement detection means 130, and the displacement detection means 130 starts the machining when the tool post is sent to the position where the machining is scheduled to start. If it is not detected, that is, if the holding shaft 120A is not displaced, it is determined that the tool is in an abnormal state such as breakage.

  Further, since the outputs of the respective hall elements 134 and 135 are waveforms having a period corresponding to the number of rotations as shown in FIGS. 5 and 6, the state detection means can also monitor the uneven rotation of the tool and abnormal rotation. Is possible.

In addition, although the displacement detection means of the said Example employ | adopts the magnetic detection means by a magnet piece and a Hall element, electrostatic detection means, an optical detection means, a physical detection means, etc. have high precision of a holding shaft. Any detection means including a contact type detection means may be used as long as it does not affect the rotation. Further, the holding shaft may hold a workpiece.
Further, when the spindle structure is applied to a detachable spindle unit, the position of the gear 126 does not change with respect to the housing 110, so that the mounting is easy and standardization is facilitated, so that an efficient machine tool can be operated. It becomes possible.
In the present embodiment, the main spindle structure is employed for the main spindle on which the processing tool is mounted as described above, but it can also be applied to a main spindle that holds a workpiece rotatably. In this case, when the workpiece or the machining tool is moved to the machining start position, the presence or absence of abnormality such as tool breakage is detected by detecting the axial displacement of the spindle due to the contact between the workpiece and the machining tool. Can be detected.

Sectional drawing of the spindle structure of the machine tool which is one Example of this invention. FIG. 2 is a partial cross-sectional view seen from the direction A in FIG. Sectional drawing of the BB line of FIG. Explanatory drawing of the displacement detection means of this invention. The wave form diagram before the processing start of the displacement detection means of this invention. The wave form figure at the time of a process of the displacement detection means of this invention. Sectional drawing of the spindle structure of the conventional machine tool.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100, 500 ... Main shaft structure 110, 510 ... Housing 110A ... Housing front part 110B ... Housing rear part 111 ... Drive shaft bearing 112 ... Holding shaft bearing 113 ... Housing fastening bolt 114 ... Fixing bolt 115 ... Fixing hole 116 ... Guide cylinder 117 ... Guide cylinder fixing nut 118 ... Key 511 ... Stopper 512 ... Thrust bearing 513 ... Bush 514 ... Main shaft holes 120, 520 ... Main shaft 120A ... Holding shaft 120B ... Drive shaft 121 ... Tool holder 122 ... Spacer 123 ... Key grooves 126, 526 ... Gears 130, 530 ... displacement detection means 131, 531 ... detection member 132 ... magnet piece 133 ... non-contact sensor 134 ... Hall element 135 ... Hall element 532 ... Rotating member 533 ... Limit switch 534 ... Bracket 140 ... Connection means 141 ... Connection pin 142 ... Groove 143 ... Cylindrical part 144 ··· Pin holding hole 150 ··· biasing means 151 ··· coil spring 152 ··· spring seat 153 · · · washer 551 · · · spring 560 · · · machining tool 580 · · · internal gear

Claims (8)

A spindle that is rotatably supported by the housing, mounts a machining tool or workpiece, and allows axial displacement of the machining tool or workpiece relative to the housing; and a displacement detection means that detects displacement of the machining tool or workpiece; In the spindle structure of the machine tool provided with the state detection means for detecting the state of the machining tool or the workpiece based on the displacement detected by the displacement detection means,
The main shaft includes a drive shaft to which a driving force is input and a holding shaft that holds a machining tool or a workpiece, and the driving shaft and the holding shaft are arranged on the same axis,
The drive shaft is supported axially fixed to the housing and rotatably driven,
A spindle structure of a machine tool, wherein the holding shaft is connected to the drive shaft so as to be elastically displaceable in an axial direction and to rotate integrally. The drive shaft and the holding shaft are connected by connecting means,
The connecting means includes a connecting pin provided in a direction intersecting the axis, a groove extending in the axial direction and engaging with the connecting pin, and a biasing means for biasing the holding shaft in a direction away from the drive shaft. The spindle structure of a machine tool according to claim 1, wherein The housing has a guide cylinder that is fixed in the axial direction and supported rotatably.
The spindle structure of a machine tool according to claim 1 or 2, wherein the holding shaft is inserted into the guide tube so as to be axially displaceable and integrally rotated.   The said displacement detection means consists of a non-contact sensor provided in the position facing the said detection member of the said housing and the detection member integrally mounted | worn with the said holding shaft. 4. The spindle structure of the machine tool according to any one of 3 above. The detection member has a magnet piece at a position facing the non-contact sensor;
The spindle structure of a machine tool according to claim 4, wherein the non-contact sensor includes a pair of Hall elements provided so as to face the vicinity of both end portions in the axial direction of the magnet piece.   The spindle structure of a machine tool according to claim 5, wherein a plurality of the magnet pieces are arranged at equal intervals in the circumferential direction.   When the workpiece is machined by the machining tool mounted on the spindle, or when the workpiece is machined by the machining tool mounted on the spindle, the state detection means is at a machining start position of the machining tool or workpiece mounted on the spindle. The spindle structure of the machine tool according to any one of claims 1 to 6, wherein abnormality of the machining tool is determined based on displacement information from the displacement detection means.   A machine tool having a spindle, comprising the spindle structure according to any one of claims 1 to 7.

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