JPH0746411Y2 - Tool holder - Google Patents

Description

TECHNICAL FIELD The present invention relates to a tool holder used for mounting a cutting tool such as a drill or boring tool on a machine tool,
In particular, the present invention relates to a technique for improving the accuracy of mounting a cutting tool on a tool holder.

2. Description of the Related Art As a tool holder for attaching a cutting tool to a machine tool, for example, there is one described in JP-A-60-221236. The tool holder includes a holder body and a collet chuck. The holder main body includes a mounting portion and a tool holding portion, a tool insertion hole is formed in the axial direction from the tip end surface of the tool holding portion, and is fixed to the machine tool at the mounting portion. The collet chuck is provided in the vicinity of the tip surface of the holder body and holds the cutting tool inserted into the tool insertion hole. In this tool holder, a drive member that is engageable with the insertion end of the cutting tool is provided in the inner part of the tool insertion hole, is fitted to the outer periphery of the holder body, and is attached to the outer peripheral end of the drive member. By rotating the adjusting nut that is screwed with the formed male screw portion by an arbitrary amount, the drive member is moved in the tool insertion hole in the axial direction and the insertion depth of the cutting tool is adjusted. . The adjust nut is fixed to the outer peripheral surface of the holder body, and is fixed immovably in the axial direction between the retaining ring that functions as a part of the tool holder after fixing and the flange portion of the holder body. When the insertion end of the tool abuts, the end surface of the flange portion on the adjustment nut side prevents the drive member from moving via the adjustment nut. That is, the end surface of the flange portion on the adjust nut side functions as a forward facing surface that contacts the rearward facing surface of the adjust nut and prevents the adjust nut from moving backward relative to the holder body.

In this tool holder, after inserting the tool into the tool insertion hole of the holder body and bringing the cutting tool into contact with the drive member, tighten the collet chuck provided near the tip surface of the holder body to reduce the collet diameter. Then, the cutting tool is gripped by the frictional force between the inner peripheral surface of the collet and the outer peripheral surface of the cutting tool.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the above tool holder, when the cutting tool is attached, a so-called runout in which the axis of the cutting tool is inclined with respect to the axis of the holder body may occur, resulting in poor attachment accuracy. There was a problem.

If the cutting tool shakes, the machining accuracy will decrease, and if the cutting tool is a drill, excessive force will act as the drilling progresses, and the drill may break.
Although various inconveniences occur, the following factors are presumed to be the cause of the reduction in the accuracy of mounting the cutting tool on the holder body.

That is, in the state where the cutting tool is inserted into the tool insertion hole, the force for pushing the cutting tool into the tool insertion hole is rigidly received by the flange portion of the holder body, that is, the front surface, via the drive member and the adjustment nut. Therefore, the cutting tool is not allowed to enter (retract) deeper into the tool insertion hole.

On the other hand, when the cutting tool is gripped by the collet chuck, a force is applied to the cutting tool to push it into the tool insertion hole. Since the collet is reduced in diameter in the taper hole by moving in the direction toward the back of the tool insertion hole, the cutting tool gripped by this collet also tends to move in the same direction. However, since the movement in this direction is blocked as described above, it is considered that a large axial compressive force is applied to the cutting tool, which causes the tool to buckle, which causes runout.

Another cause is when the collet chuck is tightened when the insert end of the cutting tool is not properly engaged with the drive member, that is, when the insert end axis is off the holder body axis. In addition, while the insertion end side is fixed as it is due to the frictional force with the drive member,
At the tip of the holder, the collet forces the axial center of the cutting tool to coincide with the axial center of the holder main body. Therefore, it is considered that the cutting tool is shaken due to the misalignment of the axial centers of both portions.

An object of the present invention is to obtain a tool holder that can accurately and satisfactorily attach a cutting tool to a holder body based on these assumptions.

Means for Solving the Problems And, the gist of the present invention is, in a tool holder provided with the holder body, a collet chuck, a drive member, a male thread and an adjusting nut, the rearward facing surface of the adjusting nut and the rearward facing surface of the holder body. This is because an elastic member such as an O-ring or a disc spring is interposed between the surface and the front surface that comes into contact with the surface and prevents the adjust nut from moving backward relative to the holder body.

In the tool holder configured as described above, when the cutting tool is inserted into the tool insertion hole, the insertion depth is defined by the front facing surface of the holder body via the drive member, the adjust nut and the elastic member. It Therefore,
When the cutting tool is repeatedly attached and detached, the position of the tip of the cutting tool is uniquely determined. However, the cutting tool is not completely immovable in the axial direction, but is movable by the amount of elastic deformation of the elastic member. Therefore, when the cutting tool is gripped by the collet chuck, a small amount of axial movement is allowed, and a large compressive force is not applied to the cutting tool. Also, if the compressive force is small, the frictional force between the insert end of the cutting tool and the surface that receives it will also be small.Therefore, even if the tool insert end is misaligned, the insert end when tightening the collet chuck The radial movement of the is not blocked by the large frictional force.

Since the elastic member regulates the insertion depth of the cutting tool as described above, when the cutting tool is inserted into the tool insertion hole by a normal force, it has a deformation resistance that does not substantially elastically deform. It is desirable to have one.

Effect of the Invention As described above, by the simple means of disposing the elastic member between the insertion end of the cutting tool into the tool insertion hole and the insertion depth defining surface of the holder main body, It is possible to effectively prevent the tool from being bent or shaken at the time of attachment, improve the attachment accuracy, and improve the processing accuracy of the workpiece.

It should be noted that the elastic deformation amount of the elastic member may be a size that allows the movement of the cutting tool along with the axial movement of the collet after the collet is reduced in diameter and grips the cutting tool in a relatively immovable manner. Since it can be made small, the interposition of the elastic member does not affect the axial position of the cutting tool to a practical extent.

Embodiment Hereinafter, an embodiment in which the present invention is applied to a tool holder for a machining center will be described in detail with reference to the drawings.

In FIG. 1, 10 is a holder main body. Holder body 10
Is composed of a large-diameter flange portion 12, a mounting portion 16 extending from an end surface 14 of the flange portion 12, and a tool holding portion 20 extending from an end surface 18. The mounting portion 16 is formed in a taper shape having a smaller diameter toward the rear end side of the holder, and is fixed to a tool mounting portion of a machine tool (not shown). A tool insertion hole 22 is formed in the center of the tool holding portion 20 so as to extend in the axial direction from the tip surface of the tool holding portion 20.
A through hole 24 that penetrates the flange portion 12 and communicates with the tool insertion hole 22 is formed in the central portion of 20.

A drive member 30 is axially movable inside the tool insertion hole 22. The main body 32 of the drive member 30 has a rectangular plate shape, and is provided with a pair of arm portions 34 (only one of which is shown in the drawing) extending at right angles to the thickness direction thereof. Each arm portion 34 penetrates through a pair of elongated holes 36 formed at diametrically separated positions of the side wall surrounding the tool insertion hole 22 of the holder body 10, and the tip end portion thereof projects from the outer peripheral surface of the holder body 10. Has been made. The elongated hole 36 has a width slightly wider than the width of the arm portion 34, so that the drive member 30
Of the holder body.
Tool holder 20 of holder body 10 parallel to the axial direction of 10
Is formed to have a length from the position adjacent to the rear end side end of the tapered hole 38 formed at the front end portion of the side to the flange portion 12. The holder main body is formed by the engagement of the long hole 36 and the arm portion 34. The rotational force of the machine tool applied to the drive member 30
To be transmitted to.

A groove 40 having a rectangular cross section is formed in the center of the end surface of the drive member 30 on the opening side of the tool insertion hole 22, and the groove 40 extends in a direction perpendicular to the direction in which the arm 34 extends. The tool 42 shown in FIG. 2 is engaged. The tool 42 is for boring, and the tip end side of the shank 43 is a blade holder 44 and the rear end side is a tongue 45. Therefore, the shank 43
Insert the tongue 45 that is the insertion end into the groove 40
When engaged with, the rotational force of the machine tool is transmitted to the tool 42.

A female screw hole 46 is further formed in the main body portion 32 of the drive member 30, and a screw portion 50 of a bolt 48 inserted into the through hole 24 is screwed into the female screw hole 46. The bolt 48 is urged toward the rear end side of the holder by a compression coil spring 56 mounted between the head portion 52 and an inward flange portion 54 formed on the inner peripheral surface of the through hole 24.

Male screw threads 58 are formed on the tip surfaces of the pair of arm portions 34 of the drive member 30, and an adjust nut 60 is screwed into the male screw threads 58. The adjustment nut 60 is formed longer than the long hole 36, and the flange portion 12
Is attached to the holder body 10 so as to be immovable in the axial direction and rotatably by an end surface 18 and a C-shaped retaining ring 62 fitted on the outer peripheral surface of the holder body 10. Therefore, when the adjusting nut 60 is rotated, the arm portion 34 is advanced or retracted and the drive member 30 is moved in the axial direction, and the tongue 45 of the tool 42 is moved by the drive member 30.
When the tool 42 is brought into contact with the bottom surface of the groove 40, the axial position of the tool 42 is changed to the drive member 30 and the adjustment nut 60.
Is defined by the end surface 18 of the flange portion 12 via. That is, in this embodiment, the end surface 18 of the flange portion 12 functions as a forward-facing surface that abuts the rearward-facing surface of the adjust nut 60 to prevent the retracting of the adjust nut relative to the holder body 10, and thereby the drive member. 30
The relative retraction of the tool with respect to the holder body is prevented, and the insertion depth of the tool 42 into the tool insertion hole 22 is defined.

An annular notch is provided at the end of the adjusting nut 60 on the end face 18 side.
64 is formed, and an O-ring 66 is fitted therein. The O-ring 66 has a diameter such that a certain amount of clearance can be formed between the adjustment nut 60 and the end surface 18 of the flange portion 12, and the axial force applied to the adjustment nut 60 causes the O-ring 66 to move. It is adapted to be received by the end face 18 through. A set screw 68 is screwed into a portion axially separated from the adjust nut 60 to prevent the adjust nut 60 from rotating except when necessary.

A collet 70 is fitted in the tapered hole 38 of the tool insertion hole 22 of the holder body 10. The diameter of the tapered hole 38 is increased toward the tip end side, and the collet 70 is fitted into the tapered hole 38 at the tapered outer peripheral surface 72 formed corresponding to the inner peripheral surface of the tapered hole 38, while the collet 70 extends in the axial direction. The inner peripheral surface 73 formed in parallel is in close contact with the outer peripheral surface of the shank portion 43 of the tool 42 and grips the shank portion 43 to receive the axial force received by the tool 42 during cutting. On the outer peripheral surface of the collet 70, further, an annular groove 74 having a rectangular cross section is formed adjacent to the portion on which the tapered outer peripheral surface 72 is formed, and a portion on which the tapered outer peripheral surface 72 is formed with the annular groove 74 interposed therebetween. On the outer peripheral surface on the opposite side, a tapered surface 76 having a diameter smaller toward the tip surface side is formed.

The tip of the collet 70 is covered with a collet cap 78. An annular groove 80 having a rectangular cross section is formed on the inner peripheral surface of the collet cap 78 at a substantially intermediate portion in the axial direction. One of the side walls 82 and 84 defining the annular groove 80 is one side wall 82. The inner peripheral surface of is a tapered surface 86 corresponding to the tapered surface 76 of the collet 70. Then, to cover the collet 70 with the collet cap 78, the diameter of the collet 70 is reduced and the side wall 84 on which the tapered surface 86 is not formed is fitted into the annular groove 74 of the collet 70. When the collet cap 78 is returned to the state, the collet cap 78 can be covered on the collet 70 while being immovable in the axial direction. Collet cap 78
In this way, the taper surface 86 is in close contact with the taper surface 76 when the collet 70 is covered,
As the diameter of the collet 70 is reduced, the collet 70 is relatively movable in the axial direction by a small distance. Annular groove 74
Is wider than the thickness of the side wall 84. Further, the length of the collet 70 is determined so that the collet cap 78 is separated from the holder body 10 by a predetermined distance.

A male screw portion 88 is formed on the outer peripheral surface of the tool holding portion 20, and a clamp nut 90 is screwed onto the male screw portion 88. The clamp nut 90 is fitted to the collet cap 78 at a portion projecting from the holder body 10. The clamp nut 90 and the collet cap 78 are rotatable relative to each other and can be rotated relative to each other by a large number of balls 92 interposed therebetween. Movement in the direction is prohibited. Therefore, when the clamp nut 90 is rotated in the direction in which it is screwed into the male screw portion 88, the collet cap 78 is moved to the rear end side of the holder and the taper surface 86 pushes the taper surface 76 of the collet 70, and the collet 70 is pressed. The diameter of 70 is reduced while being pushed into the tapered hole 38. Collet 70,
The collet chuck 78 is constituted by the collet cap 78, the male screw portion 88, the clamp nut 90 and the like. Incidentally, 96 is a plug for preventing the ball 92 from coming out.

In the tool holder configured as described above, the tool 42 is attached as follows.

First, the tool 42 is inserted into the tool insertion hole 22, and the tongue 45 is engaged with the groove 40 of the drive member 30. Then, the adjustment nut 60 is rotated to move the drive member 30 in the axial direction by an arbitrary amount to adjust the insertion depth of the tool 42 into the tool insertion hole 22. Once the proper insertion depth of the tool 42 is determined, rotate the clamp nut 90 and tighten the collet 70 via the collet cap 78, and the collet 70 will be tapered.
The shank 43 of the tool 42 is reduced while being pushed in.
Is clamped and held by the collet 70.

At this time, the axial force received by the tool 42 as the collet 70 enters the tapered hole 38 is transmitted from the tongue 45 to the end face 18 via the drive member 30, the adjust nut 60, and the O ring 66. Due to the buffering action of the O-ring 66, this axial force does not become larger than before. Therefore, tools
An excessive compressive force is not applied to 42, and buckling of the tool 42 is prevented.

Further, when the tongue 45 is brought into contact with the bottom surface of the groove 40 of the drive member 30 and the axis of the tool 42 is deviated from the axis of the holder body 10, the tongue 45 is tightened with the tightening of the collet 70. The frictional force between the drive member 30 and the drive member 30 is not so large as in the conventional case, and the inner peripheral surface 73 of the collet 70 and the shank 43 are
The alignment between the tool 42 and the holder body 10 is hardly hindered by the close contact with the outer peripheral surface of the tool.

The drive member 30 is biased toward the holder rear end side by the compression coil spring 56, so that the play between the thread groove of the adjustment nut 60 and the male thread 58 is removed, and the tool 42 of the tool 42 is removed. The insertion depth is accurately defined. Further, since the amount of elastic deformation of the O-ring is small, it hardly affects the axial position of the tool 42.
If the insertion depth of the tool 42 into the tool insertion hole 22 is determined in consideration of the amount of elastic deformation of the ring 66 in advance, the tool 42 can be positioned more accurately in the axial direction.

A test was conducted to compare the deflection of the rod when the test rod was attached to the tool holder of this example and when the similar rod was attached to the conventional tool holder not using the O-ring 66. The results are shown in FIG. In the figure, ○ indicates the value when the rod insertion end is not in contact with the drive member 30, and × indicates that the drive member 30 is moved to the tip of the long hole 36 and the rod is inserted therein. The values are obtained when the ends are brought into contact with each other, and the values indicated by Δ are values obtained when the drive member 30 is moved to the rear end of the elongated hole 36 and the insertion end of the rod is brought into contact therewith. Also, small ◯, ×, and Δ represent each measured value, and large ◯, ×, and Δ represent their average value. As is apparent from the figure, when the rod is not brought into contact with the drive member 30, the O-ring 66
Although there is almost no difference between the case where the rod is brought into contact with the drive member 30 and the case where the rod is brought into contact with the drive member 30, the deflection of the conventional tool holder without the O-ring 66 is about 4 to 27 μm. On the other hand, in the tool holder of this embodiment, it was found that the deflection of the rod was about 2 to 10 μm, which was less than half.

Further, as shown in FIG. 4 and FIG. 5, in the tool holder of the present embodiment, the rod can be attached with high accuracy without being influenced by the magnitude of the collet tightening force, and
It turned out that it was not affected by the difference in the manufacturing rod.

Although one embodiment of the present invention has been described above, the present invention is modified in various ways based on the knowledge of those skilled in the art, such as changing the O-ring to another elastic member such as a disc spring and a parallel spring. Can be carried out.

[Brief description of drawings]

FIG. 1 is a front view (partial cross section) showing a tool holder according to an embodiment of the present invention. FIG. 2 is a front view showing a tool held by the tool holder. FIGS. 3 to 5 are graphs showing the results of the test of the tool mounting accuracy of the tool holder of this embodiment. 10: Holder body, 12: Flange part 16: Mounting part, 18: End face 20: Tool holding part, 22: Tool insertion hole 42: Tool, 45: Tongue, 60: Adjust nut 66: O ring, 70: Collet 78: Collet cap, 90: Clamp nut 94: Collet chuck

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Bibliography Sho 61-20206 (JP, U) Rikai flat 1-12706 (JP, U) Rikai flat 2-19412 (JP, U)

Claims (1)

[Scope of utility model registration request] 1. A holder main body comprising a tool holding part and a mounting part, wherein a tool insertion hole is formed in the axial direction from a tip end surface of the tool holding part, and the mounting part is fixed to a machine tool, and the holder main body. A collet chuck that is provided in the vicinity of the tip surface of the tool and holds a cutting tool that is inserted into the tool insertion hole; and a cutting tool that is axially movably disposed in the inner depth of the tool insertion hole. When inserted into the insertion hole, a main body portion that abuts against the insertion hole to define the insertion depth and engages with the non-circular cross-sectional portion of the cutting tool, and is extended radially outward from the main body portion, A plurality of arms projecting from the outer peripheral surface of the holder main body through a long hole formed in the side wall surrounding the tool insertion hole of the holder main body in parallel to the axial direction. Drive to transmit And a adjust nut that is screwed into a male screw thread formed concentrically with the holder body on the tip end surface of the arm and is rotatably and axially immovably attached to the holder body. In the above, an elastic member is interposed between the rearward-facing surface of the adjustment nut and the frontward-facing surface that abuts the rearward-facing surface of the holder body to prevent the adjust nut from moving backward relative to the holder body. And tool holder.