JP2008221384A - Tool holder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a collar part into a form suitable for fixing a tool by shrink fitting by shortening the length of the collar part, in a tool holder having the collar part having a mechanism sliding in relation to a holder main body. <P>SOLUTION: This tool holder has: the holder main body having a shank part having an outer peripheral surface fitted to a tapered hole provided in a spindle shaft to a mounting object on a base end side; the cylindrical collar part externally fitted to be slidable in a shaft direction in the holder main body; and a pressing means for pressing the collar part to the base end side. The tool holder is provided with: one or more screw holes provided on a side surface of the collar part to pass through; one or more groove parts formed on a surface in contact with the collar part of the holder main body, formed to be overlapped with the screw holes and extended in the shaft direction; and a regulating member screwed into the screw hole, having a distal end part having the same outer diameter as the width of the groove part and slidably engaged to the groove part. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a tool holder for fixing a tool such as a drill to a spindle shaft of a machine tool such as a machining center.

A spindle shaft of a machining center or the like is often provided with a tapered hole, and a tool is fixed to the spindle shaft by fitting and fixing a tool holder with a tool attached to the hole. The tool holder mounting side is provided with a shank portion that fits into the tapered hole and a flange portion that abuts against the tip end surface of the spindle shaft. In many cases, the holding force is reduced because the shaft cannot be brought into contact with the end surface of the shaft. In order to solve such a problem, the following Patent Documents 1 and 2 disclose a technique for sliding the collar portion. FIG. 5 shows a half cross-sectional view of the attachment side of the tool holder having such a structure. The tool holder is separated from the holder main body 101 having a shank portion 101a with the collar portion 201 being cylindrical, and is fixed to the holder main body 101 so as to be slidable in the axial direction. The tip surface 201a of the flange 201 is brought into contact with the tip surface Aa of the spindle shaft A by pressing it toward the spindle shaft with a pressing means such as a disc spring 202. Thereby, an appropriate holding force can be ensured.
In such a tool holder, the key 102 is fixed to the key groove 101 b provided in the holder main body 101 so that the collar 201 does not rotate with respect to the holder main body 101, and the key 102 is disposed on the inner periphery of the collar 201. A groove 201b is formed to engage with. Further, a circular groove 201c is formed on the inner periphery of the upper surface of the flange 201 so that the flange 201 does not fall upward, and a C-ring 204 that engages with a groove provided in the holder main body 101 in the groove 201c. The collar 201 is pressed.
Japanese Patent No. 3180173 Japanese Patent No. 3105893

By the way, as one of the methods of fixing the tool to the tip of the tool holder, there is a method of fixing the tool by shrink fitting. Fixing by shrink fitting does not have a mechanism part, so high accuracy can be maintained, and it is suitable for a tool holder of a machine tool for precision machining. When this shrink-fit tool fixing is employed, the tool holding portion tends to be elongated in order to facilitate shrink-fit. When the tool holding portion is elongated, vibration is likely to occur. Therefore, it is desirable to make the entire tool holder as short as possible.
However, the above-mentioned tool holder in which the collar moves relative to the holder body needs to be provided with a key inside, and further requires a groove for receiving the C-ring, so the length of the collar is inevitably increased. The problem of being unsuitable for tool fixing by shrink fitting has arisen.
In view of such a problem, the present invention provides a tool holder having a mechanism in which a collar portion slides with respect to a holder body, and is suitable for fixing a tool by shrink fitting by shortening the length of the collar portion. The problem is to do.

In order to solve the above problems, the present invention has the following configuration.
According to the first aspect of the present invention, there is provided a holder body having a shank portion having an outer peripheral surface that fits into a tapered hole provided in a spindle shaft to be attached on the base end side, and is slidable in the axial direction on the holder body. In a tool holder having a cylindrical collar portion to be externally fitted and a pressing means for pressing the collar portion toward the base end side, one or more screw holes provided in a side surface of the collar portion; and the holder body One or more groove portions extending in the axial direction formed so as to overlap with the screw holes formed on the surface of the flange portion in contact with the screw holes, and the tip portions screwed into the screw holes are substantially the same as the width of the groove portions A tool holder having an outer diameter and a regulating member slidably engaged with the groove.
According to a second aspect of the present invention, in the tool holder, the flange outer peripheral surface has two engagement grooves that are opposed to engagement grooves having a predetermined length from the base end in order to engage with the spindle shaft. The screw hole is formed at a position close to the engagement groove so as to sandwich at least the engagement grooves.
According to a third aspect of the present invention, in the tool holder, the restriction member is formed by a hexagon socket set screw.
According to a fourth aspect of the present invention, the pressing means is formed in a circular shape on the inner side of the front end surface of the flange portion and a flange portion projecting in a ring shape formed at the front end position of the flange portion of the tool holder body. And a plurality of compression coil springs for applying a pressing force between the bottom of the recess and the flange portion arranged in the recess.
According to a fifth aspect of the present invention, the holder main body is divided in the axial direction at the tip end side of the groove portion, and a concave portion is formed on one of the two divided division faces, and the division is performed. A convex portion that engages with the concave portion is formed on the other side of the surface, and the concave portion and the convex portion are engaged with each other in a state where the damping alloy is held between the joint surfaces of the divided surfaces including the concave portion and the convex portion. It is fixed.

In the tool holder according to claim 1, since the length of the groove portion is sufficient if it is at least the sliding distance of the collar portion, the collar portion can be made shorter than when the key is used. Since it also serves to prevent the collar from coming off, there is no need to provide a C-ring, so there is no need to form a groove for receiving the C-ring, and the collar can be further shortened.
The invention according to claim 2 can increase the strength of the collar portion. That is, as shown in FIG. 5, it is necessary to provide the flange 201 with an engagement groove 201d for engaging with two engagement pieces protruding so as to sandwich the tool holder from the tip of the spindle shaft. When the engagement groove 201d is provided in the flange portion 201, the member at the bottom of the engagement groove 201d is inevitably thinned. However, since the driving force of the spindle shaft is directly applied to the engagement groove 201d, this thin portion, in particular, The corner portion at the bottom of the engagement groove 201d is easily damaged. Here, if the restricting member is provided so as to sandwich the engaging groove and is fixed to the holder body near the corner of the engaging groove bottom, the pressing force applied to the vicinity of the corner is restricted by the driving force of the spindle shaft. Since the member can be received most recently, it is possible to prevent the buttock from being damaged.
The invention according to claim 3 can reduce the cost by configuring the restricting member with a hexagon socket set screw.
In the invention according to claim 4, each of the disc springs used in a tool holder having a mechanism in which the collar portion slides relative to the holder main body is a compression coil spring arranged in a circular shape. Since the elastic coefficient of the compression coil spring becomes small, it becomes easy to absorb small vibrations, and vibrations due to tool fixation by shrink fitting that easily vibrates can be further suppressed.
In the invention according to claim 5, since the holder main body is divided in two and the damping alloy is sandwiched between the split surfaces, it is possible to further suppress vibration due to tool fixing by shrink fitting that easily vibrates. it can.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a front view of a tool holder X according to this embodiment, and FIG. 2 is a cross-sectional view taken along line AA of the tool holder X. The tool holder X includes a holder main body 10 and a cylindrical flange 20 fixed to the holder main body 10 so as to be relatively movable in the axial direction.
The holder body 10 has a shank portion 12 having an outer peripheral surface that fits into a tapered hole provided in a spindle shaft to be attached on the base end side, and a tool holding portion that holds and fixes the tool by shrink fitting on the distal end side. 13 is formed. A cylindrical sliding shaft portion 11 is formed between the shank portion 11 and the tool holding portion 12, and the cylindrical flange portion 20 is slidably engaged with the sliding shaft portion 11. A flange portion 11 a that protrudes in a ring shape with a large outer diameter is formed on the distal end side of the sliding shaft portion 11. On the outer peripheral surface of the sliding shaft portion 11, the tip of the male screw that engages with the screw hole 23 can slide at four positions that overlap with four screw holes 23 (described later) provided in the engaged flange 20. A groove portion 11b having a width and extending in the axial direction is formed.
In addition, the sliding shaft portion 11 is divided into two parts along the base end surface of the flange portion 11a, and a concave portion 11a is formed in the bifurcated opposing base end side sectional surface, and this concave portion 11c is formed in the distal end side sectional surface. A convex portion 11d is formed to engage with the. The convex portion 11d has a truncated cone shape, and the inner surface of the concave portion 11c has the same shape as the surface of the convex portion 11d and is formed large enough to have a gap of 0.05 to 0.3 mm. Further, the angle of the generatrix of the truncated cone constituting the convex portion 11d is formed to be about 0.2 to 5 degrees with respect to the axis. And between the opposing surfaces of the concave portion 11c, the convex portion 11d, and the ring-shaped split portion, there is a damping alloy portion constituted by a damping alloy plate that is thicker than the gap between the concave portion 11c and the convex portion 11d. It is pinched. This damping alloy part is divided into three parts so that corners are not formed. That is, the damping alloy portion includes a disc-like portion 10b that matches the upper surface of the concave portion 11c provided between the upper surface of the convex portion 11d and the bottom surface of the concave portion 11c, and the side surface of the convex portion 11d and the side surface of the concave portion 11c. A cylindrical portion 10a that matches the side shape of the convex portion 11d by winding it around the side surface of the convex portion 11d with a sector shape provided in between, and a ring-shaped portion that matches the ring shape of the partial cross section provided between the opposing split surfaces 10c. The divided portions are joined by shrink fitting. That is, the base end side having the concave portion 11c of the divided sliding shaft portion 11 is expanded by heating, and the concave portion 11c is pressed into the convex portion 11d covered with the damping alloy portion, and then cooled to reduce the size. Let me conclude. Since the convex part 11d is formed in the shape of a truncated cone, even if there is a design error in the inner diameter with the concave part 11c, it can be inserted to the position where it can be inserted by press-fitting, and thereby firmly fixed after shrink fitting. Can do. It should be noted that the gap is larger than the plate pressure of the disc-like portion 10b and the ring-like portion 10c of the damping alloy portion due to the relationship between the gap between the concave portion 11c and the convex portion 11d and the plate thickness of the damping alloy portion during design. In this case, the disk-shaped part 10b and the ring-shaped part 10 may be omitted.

The flange portion 20 is a ring-shaped member having an inner diameter that is slidably engaged with the outer diameter of the sliding shaft portion 11, and has a circular shape along the outer peripheral surface that engages with the tool changer of the machine tool on the outer peripheral surface. A groove 21 is formed along the outer periphery, and an engaging groove 22 that is a concave portion that engages with two protrusions of the spindle shaft is provided from the base end portion at an opposing position.
And the screw hole 23 is provided in two places near the engagement groove | channel 22 which pinches | interposes each engagement groove | channel 22 of the base end side rather than the groove | channel 21. FIG. FIG. 3 is a sectional view taken along line BB in FIG. The BB cross-sectional view is a cross-sectional view taken along a plane passing through the central axis of the screw hole 23. As shown in the figure, the screw hole 23 is provided close to both corners of the bottom of the engagement groove 22. As described above, the holder body 10 is formed with the groove 11b at a position overlapping the four screw holes 23, and each of the screw holes 23 is constituted by a hexagon socket set screw. By engaging the regulating member 30, the leading end of the regulating member 30 is engaged with the groove 11b, and the flange 20 is fixed to be slidable with respect to the holder body 10 by the length of the groove 11b. Become. Note that the front end surface of the regulating member 30 is set so as not to touch the bottom surface of the groove portion 11.

  In addition, a circular recess 24 along the outer edge or the inner edge is formed on the inner side of the distal end surface of the flange portion 20. The recess 24 is located at a position opposite to the base end side surface of the flange portion 11 a formed on the sliding shaft portion 11 of the holder body 10, and is between the bottom portion of the recess 24 and the base end side surface of the flange portion 11. The compression coil springs 40 are arranged in a circle. The recess 24, the flange portion 11, and the compression coil spring 40 form a pressing unit that presses the flange portion 20 toward the proximal end side. FIG. 4 is a sectional view taken along the line CC in FIG. As shown in FIG. 4, the outer diameter of the compression coil spring 40 is substantially equal to the width of the recess 24, and the compression coil spring 40 is arranged in the recess 24 without a gap. The length of the compression coil spring 40 is such a length that it can be positioned on the most proximal side by pressing the flange portion 20 whose sliding distance is restricted by the restriction member 30. A gap that is the same as or slightly wider than the slidable distance of the flange portion 20 is opened between the lower surface and the proximal end side surface of the flange portion 11. Further, a thin cylindrical skirt portion is formed on the outer peripheral distal end surface of the flange portion so that dust or the like does not enter the recess 24, and the outer peripheral side surface of the flange portion 11a is accommodated in the inner peripheral surface of the skirt portion.

  When the tool holder X having the above-described configuration is used, the shank portion 12 is engaged with the tapered hole of the spindle shaft, the upper surface of the flange portion 20 is in contact with the tip surface of the spindle shaft, and the flange portion 20 is The regulating member 30 slides along the groove 11b to be engaged. As a result, the compression coil spring 40 is compressed, and the base end surface of the flange portion 20 is pressed against the front end surface of the spindle shaft. As a result, the tool holder X is held on the spindle shaft in a stable state. As described above, the tool holder X has the same function as the conventional tool holder in which the collar portion slides with respect to the holder main body, but the length of the collar portion 20 in the axial direction is not necessary because a key is not provided. Can be formed short, so that vibration can be suppressed. Further, since the regulating member 30 is provided so as to sandwich the vicinity of the engagement groove 22 of the flange portion 20 that engages with the engagement claw at the tip of the spindle shaft, the flange portion 20 is damaged from the engagement groove 22 portion. Can be suppressed. Furthermore, by adopting a coil spring as the pressing means, it is easy to adjust the elastic force, and each coil spring can reduce the elastic coefficient, so it is easy to absorb small vibrations, and fine vibrations from the spindle axis are applied to the tool tip. It is possible to suppress transmission. Further, since the holder main body 10 is divided in the axial direction and the damping alloy is sandwiched between the divided surfaces, the vibration from the spindle shaft is absorbed by the damping alloy, so that the vibration at the tool tip is also suppressed. be able to.

  In this embodiment, the tool holding unit 13 is a shrink-fit type, but the tool holding unit 13 can be used for a general chuck type.

It is a front view of the tool holder which concerns on the form of invention. It is AA sectional drawing of FIG. It is BB sectional drawing of FIG. It is CC sectional drawing of FIG. It is a half sectional view showing a conventional tool holder.

Explanation of symbols

X Tool holder 10 Holder body 10a Damping alloy part cylindrical part 10b Damping alloy part disk part 10c Damping alloy ring part 11 Sliding shaft part 11a Flange part 11b Groove part 11c Concave part 11d Convex part 12 Shank part 13 Tool holding part 20 Gutter part 22 Engagement groove 23 Screw hole 24 Recess 30 Restriction member 40 Compression coil spring

Claims (5)

A holder main body having a shank portion having an outer peripheral surface that fits into a taper hole provided on a spindle shaft to be attached on the base end side, and a cylindrical collar portion that is externally fitted to the holder main body so as to be slidable in the axial direction. And a tool holder having a pressing means for pressing the flange toward the base end side,
One or more through-holes provided on the side surface of the buttock;
One or more grooves extending in the axial direction formed on the surface of the holder main body in contact with the flange, and formed so as to overlap the screw holes;
A tool holder having a restricting member that is screwed into the screw hole and has a distal end portion having an outer diameter substantially the same as the width of the groove portion and slidably engaged with the groove portion. On the outer peripheral surface of the flange portion, two engagement grooves having a certain length from the base end to be engaged with the spindle shaft are formed at opposite positions,
The tool holder according to claim 1, wherein the screw holes are provided at positions close to both sides of the engagement grooves so as to sandwich at least the engagement grooves.   The tool holder according to claim 1, wherein the restricting member is formed by a hexagon socket set screw. The pressing means is
A flange portion protruding in a ring shape formed at the tip position of the collar portion of the tool holder body,
A concave portion formed in a circular shape inside the front end surface of the flange,
The tool holder according to any one of claims 1 to 3, wherein the tool holder is formed of a plurality of compression coil springs that apply a pressing force between the bottom of the recess and the protruding portion, which are arranged in the recess. The holder body is bisected in the axial direction on the tip side of the groove, and has a concave portion formed on one of the opposed dividing surfaces, and a convexity that engages the concave portion on the other of the divided surfaces. The concave portion and the convex portion are engaged and fixed in a state where the damping alloy is sandwiched between the joint surfaces of the divided surfaces including the concave portion and the convex portion. The tool holder according to item 1.

Images