JP2010264554A - Collet type tool holder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a collet type tool holder coping with a large cutting torque without using a taper fitting. <P>SOLUTION: In a chuck body, inner diameter parts thereof with an interference for radially elastically deforming a shaft of the collet are formed at least at positions to divide a collet insertion hole into three equal parts. In the collet, chamfers are formed at least three equally divided portions around an outer peripheral surface of the shaft, and a slit one side of which opens axially is formed at the center of each chamfer to extend radially through a tool insertion hole of the collet. By rotating circumferentially the chuck body or the collet with the shaft of the collet inserted into a tool holder, the shaft of the collet is elastically deformed radially inwardly by the interference, and is held at the inner diameter part of the collet insertion hole. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a tool holder for attaching a cutting tool such as an end mill to a spindle hole of various machine tools, and more particularly to a press-fit type tool holder for mounting a tool via a collet.

Conventionally, various structures of collet-type tool holders have been proposed and put into practical use. For example, the structure specified in Japanese Utility Model Publication No. 58-7366 is known.
In this collet chuck structure, the clamping nut is rotated to draw a collet having a tapered shape and a slit groove on the outer periphery into the internal taper hole of the chuck, and the taper engaging portion between the two is radially reduced or enlarged. It is a very general structure that attaches and detaches the internal cutting tool, but depending on the processing, the cutting torque becomes larger than the tool holding force, and slip occurs between the holding cutting tool and the collet, There was a risk of slipping.

Also, since the slit groove end on the tip side of the collet is open, there is a possibility that cutting fluid or processing waste may enter the inside during processing, and there is a possibility that the biting phenomenon may occur when the tool is mounted. .
For this reason, for example, it has been proposed to provide a tool chuck cover described in Utility Model Registration No. 2607498 at the tip of the tool chuck to prevent entry of cutting waste, cutting fluid, and dust. Thus, it is also known that the inside of the tool chuck is dustproof and waterproof.

However, these collet chuck systems have a limit in the tool holding force, and a structure other than the collet chuck is required when machining with a larger cutting torque is performed.
In such a case, for example, it is known to use a so-called roll lock chuck described in Japanese Utility Model Publication No. 3-29051.

  This chuck structure is composed of a “holding cylinder for directly or indirectly inserting a target tool, a clamping cylinder rotatably mounted on the outer peripheral surface of the holding cylinder at a predetermined interval, and a space between the peripheral surfaces of both cylinders. With a large number of needle rollers interposed in the holding cylinder, and the needle roller is rotated and revolved while the needle cylinder rotates and revolves in a spiral manner, so that the holding cylinder is contracted and restored. " Compared to the above, high rigidity is obtained.

Therefore, even when strong cutting, that is, cutting torque is large, slip occurs between the cutting tool and the possibility of occurrence of a slip phenomenon is reduced. This chuck is also frequently used.
However, this chuck is structurally expensive, and it is difficult to construct a small-diameter tool for the structure.

Further, as so-called press-fit tool holders utilizing elastic deformation, a structure shown in Japanese Patent Application Laid-Open No. 57-33906, a structure shown in Japanese Translation of PCT International Publication No. 2002-536199, and a structure shown in US Pat. No. 6,908,085 are known. ing.
The tool holder structure disclosed in Japanese Patent Application Laid-Open No. 57-33906 is “a main body 1 provided with a center hole into which a shank of a cutting tool is inserted and a gripping portion 6 located at the tip thereof, and the main body 1 is rotatable. And a thrust ring 4 interposed between the nut and the gripping portion and supported by the tightening nut 2 via a ball screw mechanism 3. A tapered surface 7 that is tapered on the outer periphery is formed, and a tapered surface 15 that engages with the tapered surface is formed on the inner surface of the thrust ring 4.

  Moreover, the structure shown in the Japanese translations of PCT publication No. 2002-536199 gazette is "The chuck | zipper containing a sleeve (1), a tool accommodating part (3), and a connection part (5), Comprising: A tool accommodating part (3) and a connection part ( 5) is formed in one piece or formed from a plurality of joined parts, and the tool receiving part (3) is in the end area of the connecting part remote from the connecting part (5) A chuck having an axially extending recess (7) adapted to receive the tool (9) and the sleeve (1) comprising a separate element, the tool receiving part (3) being a recess In the region (7), the outer shape is conical, the wall (10) defining the inside of the sleeve (1) is conical, and the wall (10) defining the inside of the sleeve (1) is a tool. Directly against the outer surface of the storage part (3) and the tool storage part (3) Cone angle for the wall (10) defining a is approximately equal magnitude, and are characterized by a self-deterrent "is smaller.

  Further, the structure shown in US Pat. No. 6,908,085 is a chuck device for chucking a rotating part crystal comprising a collet having an outer taper and a collet holder having a taper socket. The taper socket and the outer taper of the collet have a taper angle less than the self-locking angle, a head for applying an axial force that pushes the collet into the holder, and an axial force that pulls it out of the holder, and a radius A chucking device having a plurality of radial slots defining variable segments and having a collet.

Japanese Utility Model Publication No. 58-7366 Utility Model Registration No. 2607498 Japanese Utility Model Publication No. 3-29051 JP-A-57-33906 JP 2002-536199 Gazette US Pat. No. 6,908,085

  However, the structures shown in JP-A-57-33906 and JP-T-2002-536199 all draw in a holding portion (sleeve) fitted in a taper outer peripheral surface of a member holding a cutting tool in the axial direction. Thus, the member that holds the cutting tool is held by reducing its diameter in the radial direction by elastic deformation. The screw means is used as a means for pulling the holding portion (sleeve) in the axial direction. It also has a problem that it has a great influence on tightening and is complicated in structure.

Further, the structure shown in US Pat. No. 6,908,085 is a structure in which a collet is directly pushed in the axial direction and elastically deformed in the radial direction to fix the cutting tool held at the inner diameter, and a press-fitting operation, that is, the collet is pushed in the axial direction. At this time, the collet is pushed in while being reduced in diameter, so that the cutting tool is also pressed in the axial direction, pressed against the set screw, and when the holding cutting tool diameter is small, buckling force acts on the cutting tool. Thus, there is a possibility that the flare accuracy may be adversely affected, and when the collet is replaced with a tool to be used, the flare accuracy may vary depending on the manufacturing accuracy of the collet.
Furthermore, since all of the above-described known examples are based on taper fitting, the dimension management of the taper portion is important, which is also a factor of cost increase.

  The present invention has been made to solve such a conventional problem, and an object of the present invention is to provide a press-fit collet-type tool holder that can cope with a large cutting torque without using a taper fitting. is there.

  The invention according to claim 1 includes a chuck main body having a tool holding portion provided with a collet insertion hole and a cylindrical shaft portion mounted on the inner diameter portion of the collet insertion hole. And a collet having a chamfered portion for elastically deforming the shaft portion in the radial direction at the outer diameter portion of the shaft portion, and the chuck body has a tightening margin for elastically deforming the shaft portion of the collet in the radial direction. The collet is formed in at least three equal positions of the collet insertion hole, and the collet forms a face shaving portion at least at three locations around the outer peripheral surface of the shaft portion, and at the center of the face shaving portion. A slit opened on one side in the axial direction is formed so as to penetrate the collet tool insertion hole in the radial direction, and the chuck body or collet is rotated in the circumferential direction with the collet shaft inserted in the tool holder. Let By, characterized in that the shaft portion of the collet is elastically deformed radially inside dimension configured to hold the inner diameter of the collet insertion hole by interference.

According to a second aspect of the present invention, in the collet-type tool holder according to the first aspect, an anti-rotation means is provided between the chuck body and the collet.
According to a third aspect of the present invention, in the collet-type tool holder according to the first or second aspect, a retaining means is provided between the chuck body and the collet.

According to the present invention, the press-fitting mechanism between the chuck main body and the collet is configured to use the rotation of the collet in the circumferential direction, and does not use a taper fitting mechanism as seen in the conventional axial press-fitting. Manufacturing costs can be greatly reduced.
In addition, when fixing the tool, the collet is rotated, and the collet is elastically deformed radially inward by riding a part of the collet outer periphery onto the inner diameter part formed in the collet insertion hole of the chuck body. Therefore, it is possible to reliably hold the cutting tool having an inner diameter.

Further, since the collet insertion hole of the chuck body and the collet are in contact with each other at least at three points, the flare accuracy can be improved and stabilized by the centering action.
In addition, since a means for restricting the rotation of the collet is provided between the chuck body and the collet, a good clamping position can be maintained even when manually operated (collet rotation).
In addition, since the collet retaining means is provided between the chuck body and the collet, a good clamping state can be maintained even when an excessive cutting torque is applied.

It is a partial section front view showing the collet type tool holder concerning a 1st embodiment of the present invention. It is a perspective view which shows the collet of FIG. FIGS. 2A and 2B are cross-sectional views taken along line A-A in FIG. 1, in which FIG. 1A is a cross-sectional view when a collet is inserted, and FIG. It is a BB loss-of-sight figure of FIG. It is a fragmentary sectional front view which shows the collet type tool holder which concerns on 2nd Embodiment. It is a perspective view which shows the collet used for FIG. It is CC sectional drawing of FIG. 5, (a) is sectional drawing at the time of collet insertion, (b) shows sectional drawing when a collet is rotated a predetermined angle from the state of (a). It is a fragmentary sectional view showing a collet type tool holder concerning a 3rd embodiment. It is a perspective view which shows the collet used for FIG. It is DD sectional drawing of FIG. 8, (a) is sectional drawing at the time of collet insertion, (b) is sectional drawing when a collet is rotated a predetermined angle from the state of (a). The connection part of the collet and chuck | zipper main body which concerns on 4th Embodiment is shown, (a) is sectional drawing at the time of collet insertion, (b) is sectional drawing when a collet is rotated a predetermined angle from the state of (a) It is. It is a perspective view which shows the collet which concerns on 5th Embodiment.

Hereinafter, the present invention will be described based on embodiments shown in the drawings.
(First embodiment)
1 to 4 show a collet type tool holder according to a first embodiment of the present invention.
A collet-type tool holder 1 according to the present embodiment includes a chuck body 10 and a collet 20.

The chuck body 10 includes a shank portion 11 attached to the machine tool spindle end S formed on the rear end side, a flange portion 12 formed in the middle, and a tool holding portion 13 integrally formed on the front end side. .
The tool holding portion 13 has a cylindrical shaft portion 13a, a collet insertion hole 13b is formed in the longitudinal direction at the center of the front end, and a screw hole 13e is provided in the longitudinal direction of the shaft center at the bottom.
Further, as clearly shown in FIG. 3, the collet insertion hole 13b is formed with a clearance groove 13c in the radial direction at three equal positions on the inner periphery with respect to the collet insertion hole 13b. In the figure, 13f indicates a relief hole.

On the other hand, as shown in FIG. 2, the collet 20 mounted in the collet insertion hole 13b includes a flange portion 21 formed at the tip (lower end side in the drawing) and a shaft portion formed following the flange portion 21. 22 and a tool insertion hole 24 formed through the shaft.
On the outer peripheral surface of the shaft portion 22, chamfered portions 22 a are formed at three equal portions around the periphery, and a slit 22 b opened on one side in the axial direction at the center of the chamfered portion 22 a is radially directed to the tool insertion hole 24. Is formed through. Accordingly, the shaft portion 22 of the collet 20 has a substantially triangular shape. A similar face cut portion 21 a is also formed in the tip flange portion 21 of the collet 20 in the same phase as the face cut portion 22 a of the shaft portion 22.

As shown in FIG. 3, the outer diameter dimension of the shaft portion 22 of the collet 20 is formed larger than the inner diameter dimension of the collet insertion hole 13 b of the chuck body 10.
More specifically, as shown in FIG. 3 (a), the dimensional difference between the two is the diameter, for example, an amount corresponding to the tightening allowance X of about 0.02 to 0.1 mm is outside the shaft portion 22 of the collet 20. The diameter is provided.

Further, the clearance groove 13c of the collet insertion hole 13b of the chuck body 10 is formed to a depth that is larger than the diameter of the shaft portion 22 of the collet 20 when viewed in diameter.
In FIG. 1, reference numeral 30 denotes a rear end positioning adjustment screw for the cutting tool T to be held. In addition, FIG. 1 shows an operation spanner 40, which is not shown in detail, but has a spanner coupling groove (hole) that matches the shape of the flange 21 of the collet 20, and the collet 20 is rotated by a handle. It is configured to be movable.

Next, operation | movement of the collet type tool holder 1 which concerns on this embodiment comprised in this way is demonstrated.
First, an operation when the cutting tool T such as an end mill is mounted on the chuck body 10 will be described.
After the cutting tool T is inserted into the tool insertion hole 24 formed through the shaft center of the collet 20 shown in FIG. 2, the collet 20 is mounted in the collet insertion hole 13 b of the chuck body 10. At this time, as shown in FIG. 3A, the shaft portion 22 (corresponding to the top of the triangle) of the collet 20 is inserted in accordance with the position of the escape groove 13c. And the end surface 21b of the flange 21 is contact | abutted to the end surface 13g of the cylindrical axial part 13a.
As a result, the fitting shaft portion 23 at the rear end of the collet 20 is fitted into the fitting hole 13d, and the rear end of the cutting tool T is brought into contact with the end face of the adjusting screw 30 to set the tool position according to a conventional method.

Therefore, the operation spanner 40 as shown in FIG. 1 is engaged with the flange portion 21 of the collet 20 to rotate the collet 20 with respect to the chuck body 10.
In the collet-type tool holder 1 according to the present embodiment, when rotating in one direction, the shaft portion 22 of the collet 20 is pushed into the collet insertion hole 13b of the chuck body 10. At this time, since three slits 22b penetrate the collet 20 side, the shaft portion 22 is pushed against the inner surface of the collet insertion hole 13b.
Further, by rotating the operation spanner 40 by about 60 °, as shown in FIG. 3B, the shaft portion 22 moves to the phase position of the collet insertion hole 13b and the tightening is completed.

That is, by rotating the collet 20 holding the cutting tool T in the circumferential direction, the collet 20 itself is elastically deformed radially inward and the cutting tool T is fixed. The holding force at this time can obtain an optimum value by designing the above-described fastening allowance X and the diameter (wall thickness) of the shaft portion 13a of the chuck body 10.
In addition, it is preferable to actually attach and detach the cutting tool T by changing the position of the chuck body 10 from the state of FIG. 1 by 180 °, that is, by fixing the shank portion 11 downward in the rotational direction.

Moreover, although the face-cutting part 21a of the flange part 21 of the collet 20 with which the operation spanner 40 engages is formed in three places with the same phase as the collet shaft part 22, it is not limited thereto, It can be implemented similarly by providing a shape suitable for the operation spanner 40.
Next, the collet 20 is removed by turning the operation spanner 40 in the reverse direction to change the state shown in FIG. 3B to the state shown in FIG.

According to the present embodiment, the press-fitting mechanism between the chuck body 10 and the collet 20 is configured to use rotation of the collet 20 in the circumferential direction, and a taper fitting as seen in the conventional axial press-fitting. Since no mechanism is used, the manufacturing cost can be greatly reduced.
Further, when the cutting tool T is fixed, the collet 20 is rotated so that a part of the outer periphery of the collet 20 rides on the inner diameter portion formed in the collet insertion hole 13b of the chuck body 10 so that the collet 20 is radially inward. Since the slit 22b of the collet 20 is a one-side opening, the collet 20 is deformed from the contact surface to the center, the collet 20 and the cutting tool T are in close contact, and the cutting tool having an inner diameter of the collet 20 T can be securely held. Moreover, since the deformation amount of the collet 20 does not exceed the elastic region, the reproducibility is good.

Further, since the holding hole of the chuck body 10 and the collet 20 are in three-point contact, the flare accuracy can be improved and stabilized by the centering action.
In this embodiment, the case where the collet 20 is attached to or detached from the chuck main body 10 by rotating the operation spanner 40 has been described. However, the end mill can be moved to the chuck main body 10 by rotating the chuck main body 10 side. A cutting tool T such as can be mounted or removed.

(Second Embodiment)
5-7 shows the collet type tool holder 2 which concerns on 2nd Embodiment of this invention.
The basic configuration of the collet-type tool holder 2 according to the present embodiment is the same as that of the collet-type tool holder 1 according to the first embodiment shown in FIG. 1, and the same reference numerals are given except for the configuration related to the present embodiment. Description is omitted.
The collet-type tool holder 2 according to the present embodiment is provided with a detent mechanism 130 between the rear end surface of the shaft portion 122 of the collet 120 and the bottom surface of the escape hole 113f formed in the cylindrical shaft portion 113a of the chuck body 110. ing.

On the collet 120 side, as shown in FIG. 6, three cylindrical pins 131 are planted on the rear end surface of the shaft portion 122 in a state of being divided into three equal parts.
On the other hand, three arc-shaped grooves 113h are formed at the same pitch as the cylindrical pins 131 on the bottom surface of the relief hole 113f of the cylindrical shaft portion 113a of the chuck body 110, as shown in FIG. Has been. At this time, the phase of FIG. 3A and the phase of FIG. 7A are made to coincide with each other, and the cylindrical pin 131 is disposed at one end of the arc-shaped groove 113h.

In the collet-type tool holder 2 of the second embodiment configured as described above, the cutting tool T is inserted into the collet 120 and mounted in the collet insertion hole 113b of the chuck body 110 and rotated as in the first embodiment. 3B, that is, when elastically deforming radially inward as shown in FIG. 3B, the cylindrical pin 131 is opposite to the arcuate groove 113h as shown in FIG. 7B. Abutting on the part, the relative rotation of the collet 120 and the chuck body 110 is further prevented.
In the present embodiment, the combination of the columnar pin 131 and the arc-shaped groove 113h has been described. However, the present invention is not limited to this. For example, a means for replacing the columnar pin 131 is provided on the cylindrical surface of the shaft portion 122 of the collet 120, This can also be implemented by providing means in place of the arc-shaped groove 113h on the bottom surface of the relief hole 113f of the main body 110.

(Third embodiment)
8 to 11 show a collet type tool holder 3 according to a third embodiment of the present invention.
The basic configuration of the collet-type tool holder 3 according to this embodiment is the same as that of the collet-type tool holder 1 according to the first embodiment shown in FIG. Description is omitted.

  The collet-type tool holder 3 according to the present embodiment, like the collet-type tool holder 2 according to the second embodiment, inserts the cutting tool T into the collet 220 and attaches it to the collet insertion hole 213b of the chuck body 210 to rotate. When moved, that is, when the collet 220 is elastically deformed radially inward, a mechanism for preventing the collet 220 and the chuck body 210 from coming off is provided.

In FIG. 8, a protrusion 223 a as shown in FIG. 9 is formed in a three-divided position around the tip of the shaft 222 of the collet 220.
On the other hand, the clearance hole 213f of the chuck body 210 is formed larger than the diameter of the shaft portion 222 of the collet 220, as shown in FIGS. 8 and 10B. A relief groove 213c as shown in the cross-section of FIG. 10B is formed at three equal positions on the collet insertion side end face of the relief hole 213f. And the flange is comprised in the part except this escape groove 213c.

  In this embodiment, when the collet 220 is inserted in the position shown in FIG. 10A, the rear-end protrusion 223a passes through the escape groove 213c on the chuck body 210 side and advances into the escape hole 213f. . The end face of the flange 221 of the collet 220 abuts on the end face of the cylindrical shaft portion 213a of the chuck body 210. Therefore, when the collet 220 is rotated, the protrusion 223a of the collet 220 moves to a position as shown in FIG.

  At this time, as shown in FIG. 10B, the collet 220 is elastically deformed and fixed to the collet insertion hole 213b of the chuck body 210, and the projection 223a of the collet 220 has a collet insertion hole 213b excluding the escape groove 213c. It is possible to prevent the collet 220 from coming off the chuck body 210 in the axial direction. Further, it is possible to prevent the collet 220 from falling even if an excessive cutting torque is applied during the cutting process and the collet rotates in the loosening direction.

(Fourth embodiment)
FIG. 11 shows a collet type tool holder according to a fourth embodiment of the present invention.
In the first to third embodiments, the collet 20 (120, 220) is formed in a triangular shape, and a fitting hole 13d (113d, 213d) corresponding to the collet 20 (120, 220) is provided on the chuck body 10 (110, 210) side. However, in addition to the three-part arrangement, for example, a four-divided shape as shown in FIGS. In this case as well, it can be operated as in the case of three equal parts, and high-precision tool holding is possible.

(Fifth embodiment)
First, the coolant handling will be described.
Cooling or lubricating fluid such as coolant can be supplied into the collet-type tool holders 1, 2, and 3 according to this embodiment, and can be easily sprayed to the processing point of the cutting tool T by the conventional technique.
For example, as shown in FIG. 12A, a supply passage 325 is formed on the inner surface (cutting tool insertion hole 324) of the collet 320, or as shown in FIG. 12B, the supply passage 425 is provided on the end surface of the collet 420. Can be formed.

In the collet-type tool holders 1, 2, 3 according to the above embodiments, the slit 22 b is provided on the outer periphery of the shaft portions 22, 122, 222 so that one side opens in the axial direction at the center of the chamfered portion 22 a. Although the case where it provided is demonstrated, this invention is not limited to this. For example, it is desirable to adjust the length of the slit 22b by changing the tightening allowance X according to the required tool gripping force.
The length of the slit 22b is inserted as close as possible to the flange portion 21 in order to improve tool adhesion and obtain a tool gripping force. Further, the slits 22b are advantageous in that the shaft portions 22, 122, 222 of the collets 20, 120, 220 are easily bent, the rotational torque when the tool is fixed is reduced, and workability is good.

  However, if the slit 22b is too close to the flange portion 21, it will be difficult to resist the torque at the time of collet rotation, and conversely, if the slit 22b is shallow (short), the adhesion to the cutting tool T will be low and the gripping force will also be low. Since it is low and difficult to bend, the rotational torque at the time of fixing the tool is increased and workability is deteriorated, it is desirable to keep a predetermined distance from the flange portion 21 in consideration of the required tool gripping force.

Next, the improvement in durability by coating will be described.
In the collet-type tool holders 1, 2, 3 according to the present embodiment, the contact portion of the collet 20 with the chuck body 10 side (the surface of the shaft portion 22 of the collet 20 and the collet insertion hole 13 b of the chuck body 10 in the first embodiment). The durability can be improved by applying a coating such as DLC (diamond-like carbon) to the inner surface) in consideration of frictional force and surface pressure. It is also effective to perform nitriding treatment.

1, 2, 3 Collet type tool holder 10, 110, 210 Chuck body 11 Shank part 12, 221 Flange part 13 Tool holding part 13a, 113a, 213a Shaft part 13b, 113b, 213b Collet insertion hole 13c Escape groove 13e Screw hole 13f , 113f, 213f Escape hole 13g End surface 20, 120, 220, 320, 420 of shaft portion 13a Collet 21 Flange portion 21b End surface 22, 122, 222 of flange 21 Shaft portion 22a Surface cut portion 22b Slit 24, 124, 224, 324 Tool insertion hole 30 Adjustment screw 40 Operation spanner 113h Arc-shaped groove 131 Cylindrical pin 130 Anti-rotation mechanism 223a Protrusion T Cutting tool X Tightening allowance

Claims (3)

A chuck body having a tool holding part with a mounting part to the machine tool spindle and a collet insertion hole;
A collet having a cylindrical shaft portion mounted on the inner diameter portion of the collet insertion hole, and having a chamfered portion for elastically deforming the shaft portion in the radial direction on the outer diameter portion of the shaft portion,
The chuck body has an inner diameter portion provided with a tightening margin for elastically deforming the shaft portion of the collet in a radial direction at at least three equal positions of the collet insertion hole,
The collet is formed with chamfered portions at least at three locations around the outer peripheral surface of the shaft portion, and a slit opened on one side in the axial direction is formed in the center of the chamfered portion. To penetrate in the radial direction,
By rotating the chuck body or the collet in the circumferential direction with the collet shaft inserted in the tool holding portion, the shaft of the collet is elastically deformed radially inward by the tightening allowance. The collet-type tool holder is configured to be held in the inner diameter portion of the collet insertion hole.   2. The collet-type tool holder according to claim 1, wherein a detent means is provided between the chuck body and the collet. The collet-type tool holder according to claim 1 or 2, wherein a retaining means is provided between the chuck body and the collet.

Images