JP3789323B2 - Tool holder - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a tool holder that is mounted on a spindle of a machine tool, and more particularly, to a so-called two-surface constraint type tool holder that has a tapered portion that contacts a tool mounting hole of a spindle and a flange that contacts an end surface of the spindle. .
[0002]
[Prior art]
In machine tools such as a milling machine, a machining center, and a lathe, it is common to attach a tool to a spindle via a tool holder to which a tool is attached. This tool holder is provided with a tapered portion at the base end portion disposed on the main shaft side, and the tool portion is centered by inserting and holding the tapered portion in a tool mounting hole provided on the main shaft side, while maintaining the tool. A holder is attached to the spindle.
[0003]
Generally, the tool holder includes a BT shank type in which only the conical outer peripheral surface of the tapered portion contacts the tapered hole of the main shaft, that is, the inner peripheral surface of the tool mounting hole when the tool holder is mounted on the main shaft, and the tapered portion. A flange portion is provided on the side away from the main shaft, and when the tool holder is mounted on the main shaft, the outer peripheral surface of the taper portion contacts the inner peripheral surface of the tool mounting hole of the main shaft and the flange portion positioned on the main shaft side is the end surface of the main shaft. There is a two-surface constraining type (so-called HSK shank type) that abuts with. An HSK shank type tool holder is disclosed in, for example, Japanese Utility Model Publication No. 7-40053.
[0004]
In addition, when machining a workpiece with a tool, the tool is given a large rotational force through the tool holder and at the same time receives a large reaction from the workpiece, so that the tool rotates in the tool holder and is transmitted to the tool. There is a risk of loss of rotational force of the spindle. To prevent the loss of such rotational force, JP Akira the 61-71904 discloses a tool and a positioning pin provided on the tool contact surface of the tool holder when coupling the tool holder of the tool the tool holder those An axial coupling device between a tool and a tool holder is disclosed in which the tool and the tool holder are positioned by being inserted into a hole provided in the contact portion.
[0005]
[Problems to be solved by the invention]
By the way, in the tool holder of the HSK shank type, the taper portion that comes into contact with the tool mounting hole of the main shaft is short and there is no key for positioning with the main shaft, and the tool holder itself is connected to the tool mounting hole of the main shaft, the taper portion, and the main shaft. Some of them are held with respect to the main shaft only by the frictional force between the end face and the flange portion. Such an HSK shank type tool holder has an advantage that the rotation balance is good because there is no positioning key, and the tool holder does not cause rotational shake during rotation of the spindle.
[0006]
However, HSK shank type tool holders that are not equipped with positioning keys are held only by the frictional force between the tool mounting hole of the spindle and the tapered part, and the end face of the spindle and the flange part. If it occurs, if a force exceeding the allowable value of the tool is applied by mistake, or if chatter vibrations occur, the friction coefficient decreases, causing the tool holder to slide and rotate within the tool mounting hole of the spindle, Loss of rotational force of the main shaft can occur. Furthermore, if the tool holder rotates in the tool mounting hole, there also arises a problem that the collet at the tip of the draw bar for engaging the tool holder with the main shaft can be damaged.
[0007]
Accordingly, an object of the present invention is to provide a tool holder that solves the problems in the prior art and prevents sliding rotation in the tool mounting hole of the spindle.
[0008]
[Means for Solving the Problems]
In view of the above-mentioned object, the present invention inserts a pin extending from the contact surface of the flange portion of the tool holder toward the main shaft into a pin receiving hole provided corresponding to the end surface of the main shaft, thereby The rotation is stopped.
[0009]
That is, according to the present invention, a tool holder of a two-surface restraint type that is detachably mounted on a spindle of a machine tool and does not have a positioning key between the spindle and the shank portion to which the tool is attached, and the shank A flange portion having an abutting surface that is in contact with the end surface of the main shaft, and an inner peripheral surface of a tapered tool mounting hole that is provided on the main shaft and is provided on the main shaft. contact with the tapered portion inside which a hollow formed by having the tool holder detachable mechanism provided on the spindle and engageable with circumferential inclined surface, formed by a plurality equidistant to the end surface of the spindle The tool holder is attached to the main shaft by being fixedly inserted so as to protrude from the contact surface into a plurality of holes formed at equal intervals on the contact surface of the flange portion corresponding to the position of the pin receiving hole formed. Sometimes received in the pin receiving hole, Tool holder which is adapted to and a split pin or spring pin plurality equidistant performing rotation stop of the tool holder relative to the shaft is provided.
[0011]
By inserting a pin extending from the tool holder toward the main shaft into the pin receiving hole of the main shaft, rotation of the tool holder with respect to the main shaft is prevented. Further, if only the pin receiving hole is provided in the conventional main shaft, the tool holder of the present invention can be used, and it is not hindered to attach another HSK shank type tool holder to the main shaft. Furthermore, by providing a plurality of pins equally, a tool holder with a good rotation balance can be obtained.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0013]
FIG. 1 is a cross-sectional view of the vicinity of the tip of a main shaft to which a tool holder according to the present invention is mounted, FIG. 2 is a cross-sectional view taken along the line AA of FIG. is there.
[0014]
Referring to FIG. 1, a pair of bearings 17 in which the front portion of the main shaft 13 is arranged apart from each other by a spacer 15, and the rear portion of the main shaft 13 is rotated to the main shaft head 11 of a machine tool by a bearing (not shown). A tool mounting hole 21 having a tapered hole shape for mounting the tool holder 19 is formed at the tip of the main shaft 13. An accommodation space 23 is formed at the bottom of the tool mounting hole 21, and a central hole 27 extends along the rotation axis 25 of the main shaft 13 from the accommodation space 23 toward the rear (that is, the base end side of the main shaft 13). Is further formed. As will be described later, the tool mounting hole 21, the accommodation space 23, and the center hole 27 are provided with a mechanism for detachably mounting the tool holder 19 on the main shaft 13.
[0015]
The tool holder 19 of the present invention includes a shank portion 19a to which a tool 29 such as a ball end mill is attached, a flange portion 19b provided after the shank portion 19a, and a conical shape provided after the flange portion 19b. And a tapered portion 19c having an outer peripheral surface. The flange portion 19b is a portion that is larger in the radial direction than the shank portion 19a, and has an annular contact surface 33 that is disposed so as to contact the end surface 31 of the main shaft 13 when the tool holder 19 is attached to the main shaft 13. is doing. The flange portion 19b does not necessarily have to be larger in the radial direction than the shank portion 19a as long as the annular contact surface 33 can be secured. When the tool holder 19 is mounted on the main shaft 13, the tapered portion 19 c is inserted into the tapered tool mounting hole 21 of the corresponding main shaft 13, and the conical outer peripheral surface is in contact with the inner peripheral surface of the tool mounting hole 21. It comes to contact. The tapered portion 19c is hollow inside, and a protruding portion 35 protruding radially inward is formed on the inner periphery of the tip portion, and a circumferential inclined surface 35a is formed on the inner side in the axial direction of the protruding portion 35. Has been.
[0016]
The tool holder 19 can be attached and detached by a tool holder attaching / detaching mechanism provided on the main shaft 13, and various known tool holder attaching / detaching mechanisms can be used.
[0017]
In the embodiment shown in FIG. 1, a draw bar 37 is provided in the center hole 27 of the main shaft 13 so as to be movable back and forth along the rotation axis 25 of the main shaft 13. A chuck claw 39 is disposed in the tool mounting hole 21 and the accommodation space 23 so as to straddle them. On the other hand, a circumferential inclined surface 35a formed on the inner side in the axial direction of the outer periphery of the front end portion of the draw bar 37 is engaged with a circumferential inclined surface formed on the inner side in the axial direction of the rear inner periphery of the chuck claw 39. The circumferential inclined surface formed on the inner side in the axial direction of the outer periphery of the front portion 39 is engaged with the circumferential inclined surface 35 a formed on the inner side in the axial direction of the raised portion 35 of the tool holder 19, and the central hole of the main shaft 13 27, the taper portion 19c of the tool holder 19 is pulled into the tool mounting hole 21 and fixed through the chuck pawl 39 by pulling the draw bar 37 backward (right side in the figure).
[0018]
The draw bar 37 is always urged so as to be pulled to the rear side of the main shaft 13 by a return spring 41 such as a disc spring provided in the center hole 27 of the main shaft 13, and the tool holder 19 is detached from the main shaft 13. In this case, the draw bar 37 is pushed forward by the operating means (not shown), and the circumferential inclined surface formed on the front outer periphery of the chuck claw 39 and the inner periphery of the taper portion 19c of the tool holder 19 are formed. This is done by releasing the engagement with the inclined surface 35a.
[0019]
Such a tool holder attaching / detaching mechanism for the main shaft 13 is well known and will not be described in further detail here.
[0020]
When using the HSK shank type tool holder as described above, the tool holder 19 is formed between the contact surface 33 of the flange portion 19b and the end surface 31 of the main shaft 13, and the outer peripheral surface of the taper portion 19c of the tool holder 19. The main shaft 13 is held by the main shaft 13 only by friction with the inner peripheral surface of the tool mounting hole 21 of the main shaft 13. Therefore, when vibration is generated in the main shaft 13 or the tool holder 19, a large force is applied to the tool 29, or chatter vibration is generated, the friction coefficient decreases and the tool is inserted into the tool mounting hole 21 of the main shaft 13. There is a possibility that the holder 19 is rotated and a loss of rotational force transmitted from the main shaft 13 to the tool holder 19 is caused.
[0021]
Therefore, the tool holder 19 of the present invention is a pin that protrudes from the contact surface 33 of the flange portion 19b toward the main shaft 13 along the rotation axis 25 of the tool holder 19 (that is, in a direction opposite to the shank portion 19a). 43 is further provided. 1 and 2, two pins 43 are arranged around the rotation axis 25 of the tool holder 19 at intervals of 180 degrees. Of course, three or more pins 43 may be provided on the contact surface 33. When a plurality of pins 43 are provided, as shown in FIG. 2, the pins 43 may be arranged at equiangular intervals around the rotation axis 25 of the tool holder 19 on the contact surface 33 of the flange portion 19 b. preferable. By providing the pins 43 at equiangular intervals in this way, the rotational balance of the tool holder 19 is maintained, and rotational shake is less likely to occur. The pin 43 can be easily added to the existing tool holder 19 by, for example, forming a drill hole in the contact surface 33 of the flange portion 19b and inserting a split pin or a spring pin into the drill hole. Here, it is important to use a split pin or a spring pin. This is because when the solid pin is driven into the drill hole, the end face rises and may be deformed.
[0022]
A pin receiving hole 45 is formed on the end surface 31 of the main shaft 13 corresponding to the position of the pin 43 provided in the tool holder 19. When the tool holder 19 is mounted on the main shaft 13, the tool holder 19 is adapted to receive a pin 43. In FIG. 1, two pin receiving holes 45 are formed around the rotation axis 25 of the main shaft 13 at intervals of 180 degrees. Of course, when three or more pins 43 are provided in the tool holder 19, a corresponding number of pin receiving holes 45 are also provided in a corresponding arrangement on the main shaft 13 side. The pin receiving hole 45 preferably has a larger diameter than the pin 43. Further, it is preferable that a guide taper is provided at the pin insertion opening of the pin 43 and the pin receiving hole 45. The guide taper of the pin 43 may be on both sides.
[0023]
When the tool holder 19 of the present invention is mounted on the main shaft 13, the pin 43 of the tool holder 19 is received in the pin receiving hole 45 formed in the end surface of the main shaft 13, so that the contact between the tool holder 19 and the main shaft 13 is achieved. Even when the surface friction is reduced or a large force is applied to the tool, the occurrence of sliding rotation between the tool holder 19 and the main shaft 13 is prevented. Further, since the main shaft 13 is not provided with a pin, it is possible to attach a conventional HSK shank type tool holder to the main shaft corresponding to the tool holder of the present invention.
[0024]
Here, when the tool holder 19 is mounted on the main shaft 13, the positioning of the pin 43 and the pin receiving hole 45 around the rotation axis 25 of the main shaft 13 is performed by, for example, the position (angle) orientation of the main shaft 13 when changing the tool. ing. That is, when the tool holder 19 is mounted on the pot of the tool magazine, the positioning is performed by the index hole. Then, the tool is transferred to the tool changing arm while maintaining the phase, and the tool changing arm finally attaches the tool holder 19 to the spindle 13 while preventing the phase from shifting.
[0025]
The features of the present invention have been described above by taking the HSK shank type tool holder 19 having the structure shown in FIGS. 1 to 3 as an example. However, the tool holder of the present invention has a flange portion that contacts the end surface of the spindle. A pin is provided on the contact surface, and the tool holder of the present invention is provided by providing a pin on the contact surface of the flange portion even in the case of an HSK shank type tool holder having another known structure. Can be realized.
[0026]
【The invention's effect】
As described above, according to the present invention, the pin is provided on the HSK shank type tool holder, while the main shaft is simply formed with a pin receiving hole, and the main shaft device is not remodeled at a low cost. The rotation of the tool holder in the tool mounting hole of the spindle can be prevented. Further, since only a pin receiving hole is newly formed in the main shaft, it does not hinder the mounting of the known HSK shank type tool holder to the main shaft corresponding to the tool holder of the present invention.
[0027]
Furthermore, if a plurality of pins are arranged at equal intervals around the rotation axis of the tool holder, a tool holder with good rotational stability can be provided without impairing the rotation balance of the tool holder.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of the vicinity of a spindle end equipped with a tool holder according to the present invention.
FIG. 2 is a cross-sectional view taken along the line AA of FIG.
FIG. 3 is a partially enlarged sectional view showing a pin of a tool holder and a pin receiving hole of a main shaft.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 13 ... Main shaft 19 ... Tool holder 19a ... Shank part 19b ... Flange part 19c ... Tapered part 21 ... Tool mounting hole 29 ... Tool 31 ... End surface 33 ... Contact surface 43 ... Pin 45 ... Pin receiving hole

Claims (1)

A tool holder of a two-surface constraint type that is detachably attached to a spindle of a machine tool and has no positioning key between the spindle and the spindle,
A shank part to which the tool is attached;
A flange portion that is provided following the shank portion and has a contact surface that contacts the end surface of the main shaft;
The provided subsequent to the flange portion, abut against the inner circumferential surface of the formed tapered tool mounting hole in the spindle, tool holder removal mechanism and engaging the inner side a hollow provided in the main shaft A tapered portion having a circumferential inclined surface that can be combined ;
Inserted and fixed so as to protrude from the abutment surface into a plurality of equally spaced holes in the abutment surface of the flange portion corresponding to the positions of the pin receiving holes formed in a uniform manner on the end surface of the main shaft A plurality of equally spaced split pins or spring pins that are received in the pin receiving holes when the tool holder is mounted on the main shaft and prevent the rotation of the tool holder with respect to the main shaft;
A tool holder comprising:

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