JP2009148864A - Tool holder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a press-fit-type tool holder with a small number of components and high fluctuation accuracy and flexural rigidity. <P>SOLUTION: A tapered hole of a tightening sleeve has a press-fit margin (tightening margin) for engaging with a tapered circumference of a tool holding tube, elastically deforming the tapered circumference in a radial direction as further pushed in a longitudinal direction and fixing a shank of a cutware carried in an inner diameter of the tapered circumference. A large diameter tube of the tightening sleeve has a press-fit margin (tightening margin) for elastically deforming the large diameter tube outward in the radial direction for fixedly sticking a shaft of a holder body of a tool holder body with the large diameter part by pushing the shaft into an inner diameter part. A first press-fit-fixed part is constituted of a tapered hole of the tightening sleeve engaging with the tapered circumference of the tool holding tube of the holder body and a tightening part having the tapered hole of the tightening sleeve. A second press-fit-fixed part is constituted of a cylindrical part of the shaft of the holder body and a hole formed on the large diameter tube of the tightening sleeve. <P>COPYRIGHT: (C)2009,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 improvement of a press-fit type tool holder.

  Conventionally, a press-fit type tool holder has, for example, a structure shown in JP-A-57-33906 (Patent Document 1), a structure shown in JP-T-2002-536199 (Patent Document 2), and US Pat. No. 6,908,085. The structure shown in the document (Patent Document 3) is known.

  The tool holder structure of Patent Document 1 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 of the center hole, and a tightening unit rotatably attached to the main body 1. It comprises a nut 2 and a thrust ring 4 interposed between the nut and the gripping part and supported by the tightening nut 2 via a ball screw mechanism 3, and the gripping part 6 has a taper that tapers on the outer periphery thereof. Further, the thrust ring 4 is formed with a tapered surface 15 that engages with the tapered surface.

  Further, the structure of Patent Document 2 is “a chuck including a sleeve (1), a tool storage portion (3), and a connection portion (5), wherein the tool storage portion (3) and the connection portion (5) Formed in one piece or formed from a plurality of joined parts, the tool receiving part (3) in the end area of the connecting part remote from the connecting part (5) A chuck comprising an axially extending recess (7) adapted to receive a tool (9) and the sleeve (1) comprising a separate element, the tool receiving part (3) being In the region of the recess (7), the outer shape is conical, the wall (10) defining the inside of the sleeve (1) is conical, and the wall defining the inside of the sleeve (1) (10) abuts directly against the outer surface of the tool housing (3) The a tool receptacle (3) and the cone angle is approximately equal magnitude about the wall (10) defining said inner and are characterized by a self-deterrent "is smaller.

The apparatus shown in Patent Documents 1 and 2 includes a holder body provided with a gripping portion having a tapered outer periphery located at the tip of a center hole for inserting a shank of a cutting tool, and a tapered outer periphery of the gripping portion on the inner surface. And a sleeve having a matching tapered hole, and further having a tightening nut for drawing the sleeve and elastically deforming the grip portion toward the inner diameter side.

  The chuck shown in Patent Document 3 has a collet having a tapered surface on the outside and a cutting tool insertion hole on the inside, and a collet holder having a tapered hole corresponding to the taper, and pushes the collet into the collet holder. The collet itself has a head part for drawing out. This type of chuck facilitates attachment / detachment of the cutting tool only by the operation of pushing in and pulling out the collet, achieves tool holding with a small number of components, and can provide a collet chuck with high runout accuracy.

In addition, as a tool holder that has been frequently used, there is a shrink-fit type tool holder. This type of tool holder is fixed by heating the tool insertion hole of the tool holder body to a high temperature to expand the diameter, inserting a cutting tool and cooling. A tool holder with a small number of parts and high runout accuracy can be obtained.
JP-A-57-33906 JP 2002-536199 Gazette US Pat. No. 6,908,085

However, in the apparatuses shown in Patent Documents 1 and 2, the accuracy of the threaded portion of the tightening nut used for pulling the sleeve in the axial direction may affect the tool holding portion, thereby reducing the runout accuracy. is there.
In the chuck shown in Patent Document 3, the runout accuracy as a collet chuck when holding a tool is a combination of the concentricity of the inner taper with respect to the shank taper of the collet chuck, and the concentricity of the outer taper and inner diameter of the collet. The degree of concentricity at the time was affected by the machining accuracy of each component, and higher component accuracy was required, which was a factor in increasing costs. Further, if the collet is replaced, the shake accuracy may change.

  In addition, the shrink-fit tool holder requires a cooling time for heating when used at a production site, when a cutting tool is mounted or replaced, and a long idle time until the so-called processing is started. There was a problem. In addition, repeated heating and cooling adversely affects the holder material, causing a decrease in performance (the holder material is annealed by high heat depending on the heating condition).

As described above, in the conventional tool holder, since the components are combined, it is necessary to increase the accuracy of each component, and there is a problem that the deflection accuracy of the tool holding portion is low. As a result, the cost was increased.
In addition, there is a problem in that the tool holding portion and the tightening portion (screw coupling portion) have different structures and the bending rigidity is low.

  The present invention has been made to solve such conventional problems, and an object of the present invention is to provide a press-fit tool holder having a small number of parts, high runout accuracy, and high bending rigidity.

  The invention according to claim 1 has a tool holding having a mounting portion to one end of a machine tool spindle at one end, a tapered outer periphery at the other end, and a tool mounting hole for inserting a shank of a cutting tool on the inner diameter side. A tool holder main body having a cylindrical portion, and having a shaft portion concentrically formed in the axial direction on the tool holding cylindrical portion between the attachment portion and the tool holding cylindrical portion, and a large-diameter inner diameter portion at one end. Tightening having a formed large-diameter cylindrical portion, and forming a tapered hole concentric with the large-diameter cylindrical portion to engage the tapered outer periphery of the tool holding cylindrical portion at the other end And the taper hole of the tightening sleeve is elastically deformed in the radial direction by engaging the tapered outer periphery of the tool holding cylinder portion and further pushing in the longitudinal direction. The shank part of the cutting tool held on the inner diameter of the tapered outer periphery is fixed. The large-diameter cylindrical portion of the fastening sleeve has a radius for pressing the shaft portion of the holder main body of the tool holder main body into the inner diameter portion. A taper hole of the tightening sleeve having a press-fitting allowance (tightening allowance) for elastically deforming the two in the direction and fixing them, and engaging with the taper outer periphery of the tool holding cylinder portion of the holder body; The fastening portion having the tapered hole of the fastening sleeve constitutes a first press-fit fixing portion, and the cylindrical portion of the shaft portion of the holder body and the hole formed in the large-diameter cylindrical portion of the fastening sleeve The second press-fitting and fixing portion is configured.

The invention according to claim 2 is the tool holder according to claim 1, wherein the large-diameter cylindrical portion of the tightening sleeve forms an operation portion for attaching and detaching the cutting tool.
According to a third aspect of the present invention, in the tool holder according to the first or second aspect, the tool holding cylinder portion is formed with a plurality of slits penetrating to the inner diameter.

By providing two press-fit fixing portions concentrically at a distance in the axial direction, a tool holder with higher runout accuracy can be provided.
Since the second press-fit fixing portion on the holder body side is configured with a large-diameter and integral sleeve with respect to the first press-fit fixing portion on the cutting tool holding portion side, the bending rigidity of the tool holding portion can be increased. In addition, a tool holder with a high dynamic balance can be provided.

Since the cutting tool can be mounted at room temperature, it can be used by attaching it to the spindle immediately after installation, and the idling time can be shortened at the production site, contributing to productivity improvement.
The shank at the rear end of the holder body, the tool insertion hole at the tip, and the shaft part of the second press-fit fixing part located in the middle are formed integrally. A highly accurate tool holder can be provided.

(First embodiment)
1 and 2 show a tool holder 1 according to a first embodiment of the present invention.
The tool holder 1 according to the present embodiment includes a holder body 10 and a fastening sleeve 20.

The holder body 10 has a shank portion 11 for attachment to the machine tool spindle S at one end, followed by a tool changing flange 12 for an automatic machine tool such as a machining center and a further reduced diameter shaft portion 13 for a larger diameter. And a tool holding cylinder portion 14 having a taper portion 14a of about 1/100 at the tip portion. In the figure, X indicates the formation length of the tapered portion 14a.
A through hole 15 is formed in the shaft center of the holder body 10, a tool insertion hole 16 having a predetermined depth on the tip side thereof, a screw hole 17 following the tool insertion hole 16, and the diameter of the other end is increased. That is, it opens to the end surface of the shank part 11. Further, a cylindrical portion 13 a having a smaller diameter than the shaft portion 13 is formed on the distal end side of the shaft portion 13. An annular groove 13b having a predetermined width and depth is formed in the middle of the shaft portion 13 in the longitudinal direction.

  On the other hand, the fastening sleeve 20 has a fastening part 22 in which a tapered hole 21 that engages with the outer periphery of the tapered part 14a of the tool holding cylinder part 14 of the holder body 10 is formed in the inner diameter part on the tip side, and from there It has a cylindrical portion 23 that gradually expands in diameter and extends in the axial direction, and a large-diameter cylindrical portion 24 that further increases in diameter from the middle thereof. A large-diameter hole 25 is formed on the end surface of the large-diameter cylindrical portion 24 and communicates with the cylindrical portion 23. An annular groove 24 a having a predetermined width and depth is formed in the middle of the large-diameter cylindrical portion 24, similarly to the shaft portion 13 of the holder body 10. Furthermore, a stepped portion 24 b is formed at the end of the large-diameter cylindrical portion 24 on the cylindrical portion 23 side.

In the above configuration, the tool holder 1 according to the present embodiment has a taper hole 21 that engages with the taper outer periphery of the tool holding cylinder portion 14 of the holder main body 10 and a tightening that has the taper hole 21 of the tightening sleeve 20. The portion 22 constitutes a tool holding portion H1 (first press-fit fixing portion), and further, a hole 25 formed in the cylindrical portion 13a of the shaft portion 13 of the holder main body 10 and the large-diameter cylindrical portion 24 of the fastening sleeve 20. Thus, the second press-fit fixing portion H2 is configured.
In FIG. 1, a screw member 30 that is screwed into the screw hole 17 is attached to the screw hole 17 portion of the holder body 10, and a shaft portion 30 a whose tip abuts against the tool shank end is integrally formed on the tip side. The protruding length (tip position) of the cutting tool T can be adjusted by rotating the screw member 30 with a spanner or the like (not shown) from the tip or rear end side.

Next, the first press-fit fixing portion (tool holding portion) H1 and the second press-fit fixing portion (tool holding portion) H2 will be described.
In the first press-fit fixing part (tool holding part) H1, the tapered hole 21 of the fastening sleeve 20 and the tapered part 14a of the tool holding cylinder part 14 on the holder body 10 side are both formed at the same angle. The diameter of the small diameter side is smaller than the diameter of the small diameter side of the outer periphery of the tapered portion 14a, and when the clamping sleeve 20 is pushed in the axial direction, the tightening allowance that can elastically deform the tool holding cylinder portion 14 radially inward. Combined with (press-fit).

In the second press-fit fixing portion H2, in the hole 25 formed in the cylindrical portion 13a of the shaft portion 13 of the holder body 10 and the large-diameter cylindrical portion 24 of the fastening sleeve 20, the diameter of the hole 25 is larger than the diameter of the cylindrical portion 13a. It is small and has a predetermined tightening allowance (press fit allowance).
These press-fitting allowances are set, for example, in a diameter of about 0.02 to 0.1 mm depending on the necessary tool holding force.
And the straight part of the holder body 10 needs to give a tightening allowance more than necessary in order to reinforce the bending load of the holder body 10 as a whole and to prevent falling (guide action) when the fastening sleeve 20 is inserted. In addition, when vibration is generated, the vibration can be absorbed by friction at the press-fitted portion. Therefore, the press-fitting allowance (tightening allowance) for forming the first press-fit fixing part (tool holding part) H1 is set larger than the press-fitting allowance (tightening allowance) for forming the second press-fit adhering part H2.

Next, attachment and removal operations of the cutting tool T will be described.
FIG. 1 shows a state in which the cutting tool T is mounted, and FIG. 2 shows a state in which the cutting tool T is attached to the holder body 10. The attachment and detachment of the cutting tool T are performed by a detachable device (press-fitting device) (not shown).

  When the cutting tool T is attached, as shown in FIG. 2, when the engaging portion K of the attaching / detaching device is brought into contact with the stepped portion 24b of the fastening sleeve 20 and moved to the left in FIG. In H2, the hole 25 is press-fitted while being elastically deformed so as to run on the outer diameter of the cylindrical portion 13a. On the other hand, the tapered hole 21 side of the fastening sleeve 20 is also the tapered portion 14a of the tool holding cylinder portion 14 on the holder body 10 side. Move while reducing the diameter inward. Then, the opening end surface of the hole 25 of the tightening sleeve 20 comes into contact with the end surface 13c of the holder body 10 side cylindrical portion 13a to complete.

When removing the cutting tool T, in FIG. 2, for example, the annular groove 13b of the holder main body 10 is used to fix it in the axial direction, and the annular groove 24a of the fastening sleeve 20 is fixed to the above-mentioned attaching / detaching device side. It is possible to remove the cutting tool T by engaging the engaging portion K and moving it rightward in FIG. 2 to release the two press-fitting portions.
As described above, since the two press-fit fixing portions are integrally formed on the coaxial line between the holder main body and the fastening sleeve, it is possible to form each of the parts with high accuracy, and thus to provide a tool holder with high deflection accuracy of the tool mounting portion. Can be provided.

  Further, the press-fit fixing surface (the outer periphery of the tapered hole 21 of the fastening sleeve 20 constituting the first press-fit fixing part H1 and the tapered part 14a at the tip of the tool holding cylinder part 14 of the holder main body 10, the second press-fit fixing part By applying a coating such as DLC (diamond-like carbon) to the hole 25 of the large-diameter cylindrical portion 24 of the fastening sleeve 20 constituting the H2 and the tool holding cylindrical portion 14) of the holder body 10, low friction is achieved. It is possible to improve the wear resistance and the durability. It is also effective to perform nitriding treatment.

(Second embodiment)
3A and 3B show a tool holder 1A according to the second embodiment of the present invention.
In the present embodiment, a plurality of axial slits 114a are formed in a portion corresponding to the shank fixing of the tool insertion hole 116 of the tool holding cylinder portion 114 of the holder main body 110 in the first press-fit fixing portion H1 that is a tool attaching / detaching portion. Thus, the elastic deformation through the tapered hole 121 of the fastening sleeve 120 is facilitated. Other configurations are the same as those of the first embodiment shown in FIG.

According to the present embodiment, the tool holding force can be set for lighter loads than the tool holder 1 according to the first embodiment.
In addition, although this embodiment demonstrated the case where the axial direction slit 114a was formed in the quarterly position, this invention is not restricted to this, For example, by forming two or three, etc., It can be deformed concentrically.

(Third embodiment)
4 (a) and 4 (b) show a tool holder 1B according to a third embodiment of the present invention.
In the present embodiment, a plurality of axial grooves 216 a are formed on the inner surface of the tool insertion hole 216 of the tool holding cylinder portion 214 of the holder main body 210. Other configurations are the same as those of the first embodiment shown in FIG.
According to the present embodiment, the plurality of axial grooves 216a are used as outlets for cooling and lubricating fluid, and the width and depth of the grooves are appropriately designed to facilitate elastic deformation and the tool shank. By holding it partially against the surface, the holding can be ensured.

It is a front view which shows the partial cross section of the tool holder which concerns on 1st embodiment of this invention. It is the fragmentary sectional view which expanded the press fit adhering part of FIG. (A) It is a fragmentary sectional view of the tool holding part in the tool holder concerning a second embodiment. (B) It is AA sectional drawing of Fig.3 (a). (A) It is a fragmentary sectional view of the tool insertion part of the holder main body in the tool holder which concerns on 3rd embodiment. (B) It is a BB arrow line view of Fig.4 (a).

Explanation of symbols

1, 1A, 1B Tool holder 10, 110 Holder body 11 Mounting shank part 12 Tool change flange for automatic machine tool 13 Shaft part 13a Cylindrical part 13b Annular groove 13c End face 14, 114, 214 of cylindrical part 13a Tool holding cylinder part 14a Taper portion 15 Through hole 16, 116, 216 Tool insertion hole 17 Screw hole 20 Tightening sleeve 21, 121 Taper hole 22 Tightening portion 23 Tubular portion 24 Large diameter tubular portion 24a Annular groove 24b Step portion 25 Hole 30 Screw Member 30a Shaft portion 114a Axial slit 216a Axial groove H1 First press-fit fixing portion H2 Second press-fit fixing portion K Detachment device engagement portion S Machine tool spindle T Cutting tool

Claims (3)

A tool holding cylinder part having a mounting part to the machine tool spindle end at one end, a tapered outer periphery at the other end, and a tool mounting hole for inserting a shank of a cutting tool on the inner diameter side. A tool holder body having a shaft portion formed concentrically in the axial direction between the tool holding tube portion and the tool holding tube portion;
Has a large-diameter cylindrical part with a large-diameter inner diameter part at one end and a tapered hole concentric with the large-diameter cylindrical part to engage with the tapered outer periphery of the tool-holding cylindrical part at the other end A tightening sleeve having a tightening portion, and
The taper hole of the tightening sleeve engages with the tapered outer periphery of the tool holding cylinder portion and further pushes in the longitudinal direction to elastically deform the tapered outer periphery in the radial direction, thereby causing the taper hole. It has a press-fitting allowance (tightening allowance) for fixing the shank part of the cutting tool held on the inner diameter of the outer periphery,
The large-diameter cylindrical portion of the tightening sleeve is used for elastically deforming the large-diameter cylindrical portion radially outward by pushing the shaft portion of the holder main body of the tool holder main body into the inner diameter portion, thereby fixing them together. There is a press-fit allowance (tightening allowance),
A first press-fit fixing portion is constituted by a taper hole of the tightening sleeve that engages a taper outer periphery of the tool holding cylinder portion of the holder body and a tightening portion having the taper hole of the tightening sleeve. ,
A tool holder, wherein a second press-fit fixing portion is constituted by a cylindrical portion of a shaft portion of the holder body and a hole formed in a large-diameter cylindrical portion of the fastening sleeve. The tool holder according to claim 1, wherein
The tool holder, wherein the large-diameter cylindrical portion of the fastening sleeve forms an operation portion for attaching / detaching the cutting tool. The tool holder according to claim 1 or 2,
The tool holder cylinder part is formed with a plurality of slits penetrating to the inner diameter.