JP4922476B2 - Machine tool spindle - Google Patents

Description

  The present invention relates to a spindle of a machine tool provided with a chuck that grips or releases a bar-shaped workpiece by opening and closing a chuck claw in a radial direction.

Some machine tools, such as an automatic lathe, supply a long bar through a through-hole of a main shaft, and perform continuous machining while feeding the bar by a predetermined length. A long bar is easily bent inside the through-hole due to its own weight or centrifugal force due to rotation. Due to this deflection, there is a problem that core deflection occurs in a portion of the main shaft protruding from the chuck, and precise machining becomes difficult.
Therefore, a guide tube having an inner diameter that approximates the outer diameter of the rod is inserted into the spindle through hole, and the rod is inserted into the guide tube for processing (for example, Patent Document 1, Patent Document 1). 2).
JP 2002-283104 A JP 2002-283105 A

10 and 11 are diagrams showing an example of a main shaft provided with such a guide tube, in which FIG. 10 (a) is a cross-sectional view of a main shaft front end portion, and FIG. 10 (b) is a cross-sectional view of a main shaft rear end portion. FIG. 11B is an enlarged view of the main part of FIG. 10 for explaining the support structure of the guide tube in the main shaft through hole.
In the following description, “front” refers to the left side of the figure, and “rear” refers to the right side of the figure.
The main shaft 300 rotatably supported on the main shaft 301 by a bearing 302 such as a bearing is formed with a through-hole 300a penetrating from the front end (left end in the figure) to the rear end (same right end). A built-in motor M is provided in the middle of the main shaft 300, and the main shaft 300 is rotated by driving the motor M.
A cylindrical holder sleeve 330 is fitted into the front end of the through hole 300 a of the main shaft 300. The holder sleeve 330 rotates integrally with the main shaft 300 and can move back and forth in the same direction as the main shaft axis C within the through hole 300a of the main shaft 300.

  A collet chuck 310 is inserted into the front end of the through hole 330 b of the holder sleeve 330 together with the coil spring 311. The collet chuck 310 rotates integrally with the holder sleeve 330 and can move forward and backward with respect to the holder sleeve 330. The collet chuck 310 is always urged forward by a coil spring 311 fitted in the holder sleeve 330, but is not escaped from the holder sleeve 330 and the main shaft 300 by a cap 306 screwed to the front end of the main shaft 300. It is regulated.

  A tapered surface 310 a is formed on the outer peripheral surface of the front end of the collet chuck 310, and a tapered surface 330 a that is in sliding contact with the tapered surface 310 a is formed on the inner peripheral surface of the front end of the through hole 330 b of the holder sleeve 330. Then, the holder sleeve 330 advances with respect to the collet chuck 310 while the tapered surface 330a is in sliding contact with the tapered surface 310a, whereby a chuck claw (not shown) formed at the front end of the collet chuck 310 is radially reduced in diameter. And grip the workpiece.

The rear end of the holder sleeve 330 is screwed to the front end of the draw bar 320 that moves forward and backward in the through hole 300 a of the main shaft 300, and moves forward and backward as the draw bar 320 moves forward and backward.
A drive mechanism having a cam 351 and an arm 350 is provided at the rear end portion of the draw bar 320, and the draw bar 320 moves forward and backward within the through hole 300 a of the main shaft 300 by driving the drive mechanism.

  That is, a plurality of arms 350 (two in the illustrated example) are arranged at equal intervals along the outer periphery of the main shaft 300, and can swing freely with the shaft 350a as a fulcrum. The tip of the arm 350 is in contact with the rear end of the draw bar 320 through a hole 300b formed through the peripheral wall of the main shaft 300 in accordance with the position where the arm 350 is arranged. The cam 351 can move forward and backward in the same direction as the spindle axis C by driving a driving body such as a cylinder (not shown), and the arm 350 swings in the direction indicated by the arrow I or the opposite direction by moving the cam 351 forward and backward. To do. When the cam 351 moves backward, the arm 350 rotates in the direction indicated by the arrow I in the drawing, pushes the rear end of the draw bar 320, and moves the draw bar 320 forward.

A guide tube 340 for guiding and supporting a long bar-shaped workpiece is fixed to the support sleeve 342 by inserting a support sleeve 342 attached to the rear end portion of the headstock 301 with a bolt. The guide tube 340 is inserted into a through hole 320a of the draw bar 320 disposed in front of the support sleeve 342, and further inserted into the through hole 320a of the draw bar 320 to be a bearing such as a bearing provided in the through hole 320a. 341 is supported so as to be rotatable relative to the draw bar 320 on the main axis C. In this specification, “relatively” includes all cases in which the other is in a rotating state or a moving state when viewed from one side, and one (for example, drawbar 320) is rotating or moving and the other (for example, a guide). In addition to the case where the tube 340) is stopped, the case where one and the other rotate at different rotational speeds or move at a moving speed is also included.
The front end of the guide tube 340 extends to the inside of the through hole 330 b of the holder sleeve 330 and faces the rear end of the collet chuck 310. The workpiece supplied through the guide tube 340 passes through the through hole 330 b of the holder sleeve 330 and is sent to the collet chuck 310.

  In the main shaft configured as described above, when the drive mechanism provided at the rear end portion of the draw bar 320 is driven and the draw bar 320 moves forward, the holder sleeve 330 screwed to the front end of the draw bar 320 moves forward together with the draw bar 320, and the collet chuck The chuck pawl 310 is closed to grip the workpiece. When the drive mechanism is driven and the draw bar 320 is retracted, the holder sleeve 330 is retracted to open the chuck pawl and release the workpiece.

In the main shaft configured as described above, the guide tube 340 is relatively rotatably supported by the bearing 341 attached to the draw bar 320 in the through hole 320a of the draw bar 320 that moves forward and backward. Therefore, when the draw bar 320 moves forward and backward when gripping a workpiece or releasing the grip of the workpiece, the inner ring of the bearing 341 and the guide tube 340 are rubbed and worn, and eventually the guide tube 340 is vibrated. .
The vibration of the guide tube 340 causes noise and vibration during workpiece machining, and causes a reduction in workpiece machining accuracy. Such a problem becomes more prominent in a machine tool that processes a workpiece while rotating the spindle at a high speed.
In the spindle having the above-described configuration, the gripping force of the workpiece by the chuck claw is uniquely determined by the pressure of air or the like supplied to the driving body for moving the drawbar 320 forward and backward. There has been a problem that it is difficult to adjust an appropriate gripping force in accordance with the surface finishing state.

  The present invention has been made in view of the above problems, prevents wear caused by the relative movement of the guide tube and the bearing, and is less prone to vibration and noise even at high speed rotation. The primary objective is to provide a machine tool spindle that can be kept high. The present invention also provides a spindle of a machine tool provided with an adjusting means that adjusts an appropriate gripping force according to the diameter and material of the workpiece, the surface finish state, etc. while achieving the first object. Second purpose.

To achieve the above first object, the main shaft of the present invention is formed in a hollow shape having a through hole, a chuck for gripping a work, and the work of the guide member that is provided in the through hole, the chuck A forward / backward moving member that opens and closes, and the forward / backward moving member is inserted into the through-hole so as to freely move forward / backward, and the chuck is opened / closed and guided by the guide member by the forward / backward movement of the forward / backward moving member. In the main shaft of a machine tool for gripping a workpiece, the guide member is provided between an inner peripheral surface of the through hole and an outer peripheral surface of the guide member, and the main shaft is rotatable with respect to the guide member. The bearing is disposed at a position where it does not interfere with the advance / retreat movement member, and is provided integrally with the main shaft .

According to this configuration, since the guide member is supported by the bearing provided on the main shaft so as not to rotate with respect to the main shaft, the bearing and the guide member do not relatively move forward and backward , and the guide member or the bearing Occurrence of vibration due to wear of the steel can be suppressed.
The engaging portion and the engaged portion may be any one that can open and close the chuck in accordance with the advance and retreat movement of the advance and retreat movement member, and is a taper that opens and closes the chuck by sliding the inclined surfaces. It is of a type that opens and closes the chuck by elastically deforming a part of the chuck by abutting the engaged portion against an engaging portion that is formed to protrude in the radial direction of the chuck. Also good.

Moreover, you may provide the taper-shaped guide surface which guides the end of the said workpiece | work to the said chuck | zipper in the edge part of the said advance / retreat moving member. By providing such a tapered guide surface , it is possible to smoothly supply an extremely small workpiece having an outer diameter of 2 mm or less to the chuck, and a minimum diameter hole allows the workpiece to be moved between the chuck and the guide member. Since it supports, the vibration of the workpiece | work during rotation of a main axis | shaft can be suppressed and the mechanical vibration generate | occur | produced during rotation of a main axis | shaft can be made small.

In this case, the drive means for moving the advance / retreat means may be provided on an outer peripheral portion of the main shaft .

As a specific configuration of the driving means, a cylinder and a piston provided in the cylinder so as to be movable back and forth may be provided, and the advance / retreat member may be moved by movement of the piston .
Moreover, it has a moving body which moves the said advance / retreat moving member, and this moving body and the said piston may be integrally formed or connected .

There may be provided an urging means for constantly urging the advance / retreat movement member, and the drive means moves the advance / retreat movement member against the urging force of the urging means.

In order to achieve the second object of the present invention, the present invention provides a movable body that is movable forward and backward with respect to the main shaft, moves the forward / backward moving member, and moves forward and backward to the movable body. A contact member that is integrally provided so as to protrude to the outside of the member and a position that can be adjusted on the outside of the advance / retreat member, and the movement of the advance / retreat member is restricted by contacting the contact member. And a stopper to be used .
According to this configuration, the movement of the advance / retreat member to one side is regulated by positioning the stopper at a predetermined position on the movement axis of the advance / retreat member, thereby adjusting the gripping force of the workpiece by the chuck. be able to.

In this case, the stopper is a dial scale is attached to the rotating direction in advance by the differential pitch, it may be configured to have a fixed means for positioning and fixing the dial at a predetermined position.
By configuring in this way, the most advanced position of the advancing / retreating member is adjusted as appropriate, and the gripping force of the workpiece by the chuck is optimized according to the outer diameter size and material of the workpiece, the finish state of the workpiece surface, etc. can do.

Since the present invention is configured as described above, the bearing interposed between the main shaft and the guide tube only supports the guide tube so as to be rotatable relative to the main shaft. It does not move forward and backward relatively, and therefore wear is less likely to occur on both the guide tube and the inner ring of the bearing.
For this reason, even if the guide tube is used for a long period of time, it is difficult for vibration to occur in the guide tube, and high-precision machining can be maintained for a long period of time, particularly under high-speed rotation.
In addition, by providing a stopper that regulates the most advanced position of the advancing / retreating movement member and making it possible to adjust the position of the stopper, the gripping force of the work by the chuck can be optimized according to the work to be processed. it can.

Further, in the present invention, a draw bar for opening and closing the chuck is not necessary, and a driving body for moving the advancing / retreating member for moving the chuck back and forth is disposed on the outer peripheral portion in front of the main shaft. There is an advantage that the total length can be shortened. In particular, in a machine tool in which the spindle is rotated by a built-in type motor as shown in FIG. 10, if the driving means for opening and closing the chuck is arranged at the rear (the other side) of the motor, the entire length of the spindle increases accordingly. However, in the present invention, since the driving means is provided in front of the main shaft (one side), the chuck opening / closing mechanism can be made compact even in such a built-in type main shaft, and the size of the machine tool can be reduced. This is advantageous in that it can be realized.

DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view of a front end portion of a main shaft showing a state in which a holder sleeve is advanced and a work is gripped by a collet chuck according to an embodiment of the main shaft of the present invention.
In the following description, “front” indicates the left side of FIG. 1, and “rear” indicates the right side.

The main shaft 100 is preferably rotatably supported on the main shaft 101 by a bearing 102 such as a bearing. The main shaft 100 is formed with a through hole 100a that extends from the front end to the rear end along the main shaft axis C.
A cylindrical holder sleeve 130 which is an advance / retreat member is fitted into the front end of the through hole 100a. A collet chuck 110 serving as a chuck for gripping the front end portion of the long rod-shaped workpiece is mounted on the front end of the through hole 100a of the main shaft 100 while being fitted into the holder sleeve 130.

  The collet chuck 110 rotates integrally with the holder sleeve 130 and the main shaft 100 and can move forward and backward with respect to the holder sleeve 130. In addition, a coil spring 111 as an urging means is fitted to the rear portion of the through hole 130b of the holder sleeve 130, and the collet chuck 110 is constantly urged forward.

  A tapered hole 133 formed on the axis C at the rear end of the through hole 130b is used to guide the tip of a rod-shaped workpiece, which is fed while being guided by a cylindrical guide tube 140, which will be described later, to the center axis (axis line of the collet chuck 110). To match (C). The tapered hole 133 includes a minimum diameter hole 133a located on the front side on the axis C and a maximum diameter hole 133b located on the rear side. The hole diameter of the smallest diameter hole 133a located on the front side is the same as the outer diameter of the work so long as the work can be smoothly guided between the claws of the collet chuck 110, preferably within a range that does not prevent the work from moving forward and backward. It is good to form to the dimension.

The hole diameter of the largest diameter hole 130b located on the rear side is such that the tip of the rod-shaped workpiece can be reliably guided from the guide tube 140 to the smallest diameter hole 133a, preferably the inner diameter of the through hole of the guide tube 140 Form larger than. In this embodiment, the inclined surface between the minimum diameter hole 133a and the maximum diameter hole 133b forms a guide surface that guides one end of the work fed from the front end of the guide tube 140 to the minimum diameter hole 133a. Such a taper hole 133 is advantageous for smooth supply of an ultra-fine workpiece having an outer diameter of 2 mm or less, and the minimum-diameter hole 133a supports the workpiece between the collet chuck 110 and the guide tube 140. There is an effect that the vibration of the workpiece during the rotation of the main shaft 100 can be suppressed and the mechanical vibration generated particularly during the high-speed rotation can be reduced.
At the front end of the main shaft 100, a cap 106 is attached as a restricting member that restricts the collet chuck 110 from escape from the holder sleeve 130 and the main shaft 100. The collet chuck 110 is always pressed against the cap 106 by the biasing force of the coil spring 111.

  The inner peripheral surface of the front end of the through hole 130 b of the holder sleeve 130 is formed as a tapered surface 130 a that is in sliding contact with the tapered surface 110 a formed on the outer peripheral surface of the front end of the collet chuck 110. Then, the chuck sleeve (not shown) formed at the front end of the collet chuck 110 is moved in the radial direction by advancing the holder sleeve 130 with respect to the collet chuck 110 while the tapered surface 130a and the tapered surface 110a are in sliding contact with each other. Reduce the diameter and grip the workpiece.

A key groove 130c is formed in the rear end portion of the holder sleeve 130 in the same direction as the spindle axis C, and is engaged with a sliding key 132 attached to the inner peripheral surface of the spindle through hole 100a. Therefore, the holder sleeve 130 rotates integrally with the main shaft 100 and can move forward and backward with respect to the main shaft 100.
A flange 131 projecting in the radial direction is formed at the front end of the holder sleeve 130. The outer peripheral edge of the flange 131 protrudes radially outward from the outer peripheral surface of the main shaft 100 so that a piston rod 151 of a driving means described later can be engaged with the flange 131.

A cylindrical guide tube 140 is disposed in the through-hole 100a behind the holder sleeve 130 to support the workpiece being processed and guide the feeding of the workpiece after completion of the processing. The inner diameter of the through hole of the guide tube 140 is preferably set to a dimension that matches or approximates the outer diameter of the work in order to suppress the deflection of the work due to rotation during processing. You may make it form larger than an outer diameter and to support a workpiece | work with the supporting member provided in the multiple places in the said through-hole. Further, when the workpiece is fed by gripping the rear end of the workpiece with the finger provided at the front end of the push rod, the inner diameter of the through hole is matched with the finger within a range that does not hinder the forward and backward movement of the finger. The size should be good.
The front end of the guide tube 140 is preferably as close to the holder sleeve 130 as possible within a range that does not interfere with the holder sleeve 130. The guide tube 140 is rotatably supported relative to the main shaft 100 on the main shaft axis C by a bearing 105 such as a bearing provided in the main shaft through hole 100a.

Next, driving means for moving the holder sleeve 130 forward and backward to open and close the chuck pawl of the collet chuck 110 will be described.
The driving means includes a cylinder 152 provided on the outer peripheral portion of the front end portion of the main shaft 100, a piston 150 that moves forward and backward in the cylinder 152, and a piston rod 151 as a moving body that moves forward and backward together with the piston 150. ing.
A cylinder chamber 153 is formed between the rear bottom portion of the cylinder 152 and the piston 150, and air flow paths 155 and 152 a are formed from the headstock 101 to the cylinder chamber 153 through the rotary joint 154. Then, by supplying a pressure fluid such as air from the air flow paths 155 and 152a to the cylinder chamber 153, the piston 150 and the piston rod 151 move forward.
The cylinder 152 is screwed to a spiral portion formed on the outer peripheral surface of the main shaft 100. The cap 106 that restricts the escape of the collet chuck 110 is screwed into a spiral portion formed on the outer peripheral surface of the front end of the cylinder 152.

  In this embodiment, the piston 150 and the piston rod 151 are integrally formed and are externally fitted to the front end portion of the main shaft 100 so as to be movable forward and backward. The front end of the piston rod 151 is opposed to the flange 131 of the holder sleeve 130 projecting radially outward from the outer peripheral surface of the main shaft 100. When the piston 150 and the piston rod 151 are advanced, the front end of the piston rod 151 is flanged. The holder sleeve 130 is pushed forward in contact with 131.

  In this embodiment, the piston 150 and the piston rod 151 are retracted by the biasing force of the coil spring 111 inserted into the holder sleeve 130. Of course, a spring may be provided separately from the coil spring 111, and the piston 150 and the piston rod 151 may be retracted by the biasing force of the spring.

The spindle of this embodiment is provided with adjusting means for adjusting the opening / closing amount of the chuck claw, and the gripping force of the work by the chuck claw of the collet chuck 110 according to the workpiece diameter, material, surface finish condition, etc. Can be adjusted to an appropriate one.
Hereinafter, the configuration and operation of the adjusting means will be described with reference to FIG.
In the spindle of this embodiment, the collet chuck 110 is constantly pressed against the cap 106 by the coil spring 111 and does not move. Therefore, the chuck pawl is opened and closed only in the radial direction to grip or release the workpiece. Therefore, by changing the forward movement amount of the holder sleeve 130 relative to the collet chuck 100, that is, the most advanced positions of the piston 150 and the piston rod 151, the opening / closing amount of the chuck pawl (work gripping force) can be adjusted. is there.

  Therefore, in the main shaft of this embodiment, a spiral groove 106a having a precise spiral pitch is formed on the outer periphery of the cap 106, and a dial 120 as a stopper is screwed into the spiral groove 106a. The outer peripheral surface of the dial 120 is graduated with a uniform pitch so that the amount of rotation of the dial 120 can be finely adjusted.

A contact member 160 that contacts the dial 120 is provided outside the cylinder 152. The contact member 160 is connected to the piston 150 by a hollow mounting member 162 that passes through the wall portion of the cylinder 152 and a bolt 161 that is inserted through the mounting member 162 and screwed into the piston 150. Accordingly, the abutting member 160 moves forward integrally with the piston 150 and the piston rod 151, and the advancing of the piston 150 and the piston rod 151 is restricted by the abutting member 160 coming into contact with the dial 120. In this embodiment, the contact member 160 constitutes a stopper that restricts the advance of the holder sleeve 130 that is an advance / retreat member.
Reference numeral 165 denotes a sensor such as a proximity switch that detects that the contact member 160 has been reliably retracted.

The dial 120 is provided with fixing means including a bolt 121 and a piece 122. This fixing means is for positioning and fixing the dial 120 at an arbitrary rotational angle position.
The bolt 121 is screwed into a spiral hole formed in the dial 120 in the same direction as the main axis C, and the piece 122 is a hole formed in the radial direction from the inner peripheral surface of the dial 120 so as to communicate with the spiral hole. Has been inserted. The dial 120 is fixed to the cap 106 by tightening the bolt 121 screwed into the spiral hole and pressing the piece 122 against the outer peripheral surface of the cap 106.

A change b of the advance amount of the piston 150 and the piston rod 151 and a change a of the closing amount of the chuck claw of the collet chuck 110 by rotating the dial 120 by an angle θ (indicated by an arrow θ in FIG. 3A). Is determined based on the pitch p of the spiral groove 106a and the taper angle α of the tapered surface 110a of the collet chuck 110.
That is, the change b of the advance amount (indicated by an arrow b in FIG. 3B) is represented by p × θ / 360, and the change amount a of the close amount a (indicated by an arrow a in FIG. 3B) is b. Since it is expressed by x tan α / 2, the relationship between the change amount a of the closing amount a and the rotation angle θ of the dial 120 can be expressed by a = p × θ / 360 × tan α / 2.

For example, when the pitch p of the spiral groove 106a is 0.5 mm, the taper angle α is 30 ° (gradient angle α / 2 = 15 °), and the dial 120 is provided with a scale that divides the entire circumference into 50 equal parts. The change a of the closing amount of the chuck claw when 120 is rotated by one division (θ = 7.2 °) is
a = p × θ / 360 × tan α / 2 = 0.5 × 0.02 × tan 15 °
= 0.0027 mm.

Since the change amount a of the closing amount of the chuck claw is only on one side, the change amount of the substantial closing amount of the chuck claw of the collet chuck 110 is 0.0054 mm which is twice the above.
As described above, since the closing amount of the chuck claw of the collet chuck 110 can be finely adjusted, the opening / closing amount of the chuck claw can be changed in accordance with a change in the workpiece diameter, a change in the workpiece material, a surface finish state of the workpiece, and the like. Can be finely adjusted to grip the workpiece with the optimum gripping force.

[Operation of main shaft]
The operation of the main shaft having the above configuration will be described with reference to FIGS.
FIG. 2 is a cross-sectional view of the front end portion of the main spindle showing a state in which the holder sleeve is moved backward to release the workpiece gripped by the collet chuck.
In an initial state before starting the machining of the workpiece, as shown in FIG. 2, the piston 150, the piston rod 151, and the holder sleeve 130 are retracted, and the chuck pawl of the collet chuck 110 is in an open state.
In starting the machining of the workpiece, the guide sleeve 140 is inserted to feed the workpiece forward, and the front end of the workpiece protrudes from the front end of the collet chuck 110 by a predetermined length.

In this state, pressure fluid such as air is supplied from the air flow paths 155 and 152a to the cylinder chamber 153, and the holder sleeve 130 is advanced together with the piston 150 and the piston rod 151. As a result, the taper surface 130a of the holder sleeve 130 and the taper surface 110a of the collet chuck 110 are brought into sliding contact with each other to close the chuck pawl and grip the workpiece. Since the advance position of the holder sleeve 130 is determined by the contact member 160 coming into contact with the dial 120, the gripping force of the work is optimum according to the work.
Thereafter, the workpiece is processed by a tool (not shown) while rotating the spindle 100. The workpiece is supported by a guide tube 140 positioned immediately after the holder sleeve 130 while being held by the collet chuck 110. For this reason, it is possible to suppress a decrease in machining accuracy due to run-out and waviness of a long workpiece and perform high-precision machining.

After the processing is completed, a switching valve (not shown) is operated to open the cylinder chamber 153 to the atmosphere. As a result, the holder sleeve 130, the piston 150, and the piston rod 151 are retracted by the biasing force of the coil spring 111, and the chuck pawl of the collet chuck 110 is opened to release the workpiece.
Thereafter, a work pusher of a bar feeder (not shown) pushes the work from behind to advance it. When the front end of the workpiece protrudes from the front end of the collet chuck 110 by a predetermined dimension, the workpiece feed is stopped. Then, a pressure fluid such as air is supplied to the cylinder chamber 153 in the same procedure as described above, and the holder sleeve 130, the piston 150 and the piston rod 151 move forward to close the chuck pawl and grip the workpiece.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG.
In this embodiment, the same parts and members as those of the previous embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.
In this embodiment, not only forward movement but also backward movement of the piston 150 is performed by air pressure.
That is, as shown in FIG. 4, in the headstock 101, air passages 157 and 152b for retreating the piston 150 are formed in addition to the air passages 155 and 152a for moving the piston 150 forward. A rotary joint 154 that communicates with the air flow path 155 and a rotary joint 156 that communicates with the air flow path 157 are formed between the cylinder 152 and the front and rear positions.
According to this aspect, when the workpiece is gripped by the collet chuck 110, air is supplied from the air flow paths 155 and 152a to the cylinder chamber 153a behind the piston to advance the piston 150, and the workpiece is gripped by the collet chuck 110. When releasing, air is supplied from the air flow paths 157 and 152b to the cylinder chamber 153b in front of the piston to retract the piston 150.

[Third embodiment]
Next, a third embodiment of the present invention will be described with reference to FIG.
In this embodiment, the piston 150 is retracted by air supplied from the air flow paths 157 and 152b to the cylinder chamber 153b in front of the piston, as in the second embodiment. This is done by the urging force of the disc spring 158 disposed behind the disc spring receiver 158a.

[Fourth embodiment]
Next, a fourth embodiment of the present invention will be described with reference to FIGS.
In this embodiment, the piston 150 'is formed integrally with the holder sleeve 130', and the holder sleeve 130 'is moved forward and backward together with the piston 150'.
In the example shown in FIG. 6, as in the first embodiment, the holder sleeve 130 ′ moves forward by supplying air to the cylinder chamber 153 behind the piston via the air flow paths 155 and 152 a. Further, by releasing the air in the cylinder chamber 153 to the atmosphere via the air flow paths 155 and 152 a, the holder sleeve 130 ′ is retracted by the urging force of the spring 111.

In the example shown in FIG. 7, as in the second embodiment, the holder sleeve 130 'moves forward by supplying air to the cylinder chamber 153a behind the piston via the air flow paths 155 and 152a. Further, by supplying air to the cylinder chamber 153b in front of the piston via the air flow paths 157 and 152b, the holder sleeve 130 'moves backward.
In the example shown in FIG. 8, as in the third embodiment, the holder sleeve 130 'moves backward by supplying air to the cylinder chamber 153b in front of the piston via the air flow paths 157 and 152b. Further, the holder sleeve 130 'moves forward by the biasing force of the disc spring 158 disposed behind the piston 150'.

[Fifth embodiment]
Next, a fifth embodiment of the present invention will be described with reference to FIG.
In this embodiment, driving means for opening and closing the collet chuck is provided behind the collet chuck. The driving means in the example shown in FIG. 9 has the same configuration as the driving means in the conventional example shown in FIG. That is, the driving means includes a cam 251 that is movable back and forth in the direction of the main axis A, and a plurality of members that rotate in the direction indicated by the arrow I in the drawing or the opposite direction with the shaft 250a as a fulcrum as the cam 251 moves back and forth. Arm 250. The cam 251 moves forward and backward by driving a driving body (not shown) such as a cylinder.

A cylindrical transmission member 252 is disposed behind the holder sleeve 130, and its front end is in contact with the rear end of the holder sleeve 130. Further, the distal end of the arm 250 is in contact with the rear end of the transmission member 252.
The guide tube 240 is rotatably supported relative to the main shaft 200 in the through hole 200a by at least one bearing 205 (preferably a bearing) provided in the through hole 200a of the main shaft 200. One of the bearings 205 is disposed at a position that does not interfere with the arm 250 behind the arm 250, and a guide tube 240 that extends through the bearing 205 and extends forward is in a cantilever state, and the through hole 252 a of the transmission member 252. Has been inserted. The front end of the guide tube 240 is preferably located as close to the collet chuck 110 as possible, but extends to the rear end of the holder sleeve 130 in the embodiment shown in FIG.

In the main shaft 200 having the above-described configuration, when the cam 251 is retracted by driving of a driving body (not shown) and the arm 250 rotates in the direction indicated by the symbol I in the drawing, the transmission member 252 is pushed forward by the arm 250, and accordingly As a result, the holder sleeve 130 moves forward and the workpiece is gripped by the collet chuck 110.
Further, when the driving body is driven and the cam 251 advances, the arm 250 rotates in the opposite direction (the direction opposite to the direction indicated by the arrow I) to release the pressure on the transmission member 252, so that the holder sleeve 130 and The transmission member 252 is retracted by the urging force of the coil spring 111 and the gripping of the workpiece by the collet chuck 110 is released.

Although preferred embodiments of the present invention have been described, the present invention is not limited to the above-described embodiments.
For example, in the above description of the first to third embodiments, the engagement between the flange 131 that is the engaging portion of the holder sleeve 130 as the advance / retreat moving member and the piston rod 151 as the moving body is the outer periphery of the main shaft 100. Although described as being performed outside the surface, the engagement between the advancing / retreating movement member and the moving body may be performed inside the through hole 100a of the main shaft 100.

  In the above description, the chuck pawl is opened and closed by sliding the tapered surface 110a of the collet chuck 110 and the tapered surface 130a of the holder sleeve 130. However, the chuck pawl can be opened and closed. If so, the engaging portion and the engaged portion are not limited to the above. For example, an engaging portion that protrudes in the radial direction is formed at the front end of the collet chuck 110, and an engaged portion that is abutted against the engaging portion is formed at the tip of the holder sleeve 130, so that the holder sleeve 130 advances. Thus, the engaged portion may be configured to press the engaging portion to elastically deform the front end of the collet chuck 110 and close the chuck pawl.

Furthermore, in the fifth embodiment, the holder sleeve 130 and the transmission member 252 are pushed back only by the urging force of the coil spring 111, but the holder sleeve is driven by driving of another spring or a driving body such as a cylinder. 130 and the transmission member 252 may be configured to retract. Furthermore, as a modification of the fifth embodiment, a driving body including a cylinder and a piston may be used instead of the cam 251 and the arm 250.
Furthermore, in the present invention, other driving bodies such as a linear motor and a solenoid can be used as long as the advance / retreat moving member can be moved back and forth.

  The present invention can be applied to the spindles of all types of machine tools as long as the chuck claw is opened and closed in the radial direction to grip and release the workpiece. In the above embodiment, the description has been made on the assumption that the spindle is provided with a push-type chuck that grips a workpiece by pushing the chuck forward, but the present invention draws the chuck into the spindle through-hole. It can also be applied to a spindle equipped with a pull-type chuck for gripping a workpiece.

FIG. 3 is a cross-sectional view of the front end portion of the main shaft showing a state in which the holder sleeve is advanced and the work is gripped by the collet chuck according to one embodiment of the main shaft of the present invention. It is sectional drawing of the spindle front end part which shows the state which retracted the holder sleeve and cancel | released the holding | grip of the workpiece | work by a collet chuck. It is a figure explaining the structure and effect | action of an adjustment means. It is sectional drawing of the spindle front end part concerning 2nd embodiment of this invention. It is sectional drawing of the spindle front end part concerning 3rd embodiment of this invention. It is sectional drawing of the spindle front end part concerning 4th embodiment of this invention. It is sectional drawing of the spindle front end part which shows the modification of 4th embodiment of this invention. It is sectional drawing of the spindle front end part which shows the other modification of 4th embodiment. It is sectional drawing of the spindle front end part concerning 5th embodiment of this invention. FIG. 10A is a cross-sectional view of a main shaft front end portion, and FIG. 10B is a cross-sectional view of a main shaft rear end portion according to a conventional example of the present invention. It is an enlarged view of the principal part of Fig.10 (a) for demonstrating the support structure of the guide tube in a main axis through-hole.

Explanation of symbols

100: Main shaft 100a: Main shaft through hole 101: Main shaft base 105: Bearing 106: Cap 106a: Screw groove 110: Collet chuck 110a: Tapered surface 111: Coil spring 120: Dial 121: Bolt 122: Piece 130: Holder sleeve 130a: Taper Surface 130b: Through hole 131: Flange 132: Sliding key 140: Guide tube 150: Piston 151: Piston rod 152: Cylinder 153: Cylinder chambers 154, 156: Rotary joints 155, 157: Air flow path 160: Abutting member 162: Mounting member 165: sensor

Claims (8)

Is formed in a hollow shape having a through hole, a chuck for gripping a work, and the work of the guide member that is provided in the through-hole, and a forward and backward movement member for opening and closing the chuck, said reciprocating moving member, wherein In a spindle of a machine tool that is inserted into a through-hole so as to be movable forward and backward, opens and closes the chuck by the forward and backward movement of the forward and backward movement member, and grips a workpiece guided by the guide member ,
A bearing that is provided between an inner peripheral surface of the through hole and an outer peripheral surface of the guide member, and supports the guide member so that the main shaft is rotatable with respect to the guide member ;
The bearing is disposed at a position not interfering with the advance / retreat moving member, and is provided integrally with the main shaft ,
Main axis of machine tool characterized by The spindle of the machine tool according to claim 1, wherein a tapered guide surface that guides one end of the workpiece to the chuck is provided at an end of the advance / retreat member. The spindle of a machine tool according to claim 1 or 2, wherein a driving means for moving the advancing / retreating means is provided on an outer peripheral portion of the spindle. The machine tool according to claim 2 or 3, wherein the driving means includes a cylinder and a piston provided in the cylinder so as to be movable forward and backward, and moves the forward / backward moving member by movement of the piston. The main axis. 5. The spindle of a machine tool according to claim 4, further comprising a moving body that moves the advancing / retreating member, wherein the moving body and the piston are integrally formed or connected. 6. A biasing means for constantly biasing the advance / retreat movement member is provided, and the drive means moves the advance / retreat movement member against the biasing force of the biasing means. The spindle of the machine tool described in 1. A movable body that is provided so as to be movable forward and backward with respect to the main shaft, and that moves the forward and backward moving member;
An abutting member provided integrally with the moving body so as to protrude to the outside of the advance / retreat moving member;
7. The apparatus according to claim 1 , further comprising a stopper that is provided on an outer side of the advance / retreat movement member so that the position of the advance / retreat movement member can be adjusted, and that restricts movement of the advance / retreat movement member by contacting the contact member. Main spindle of the machine tool described. 8. The spindle of a machine tool according to claim 7, wherein the stopper includes a dial that is prescaled in the rotation direction at an equal pitch, and a fixing means that positions and fixes the dial at a predetermined position .

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