JP2002283162A - Shrink fitting tool holder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fix a tool of a small diameter, to fix tools of a large size range by the same holder, to correct vibrations of the tool after fixing, and to simply set the insertion length of the tool. SOLUTION: A tool holder 10 is provided with a tapered shank portion 11 fitted in a machine tool at one side, and a chuck portion 13 fixing a shank of a tool by shrink fitting at the other side. A cylindrical sleeve 20 is interposed between the shank of the tool and the chuck portion 13, and a slit 22 and a collar 21 are formed on the sleeve 20. The sleeve 20 is made of a material having a coefficient of thermal expansion smaller than that of the chuck portion of the tool holder, and a screw hole 23 is provided on the end surface of the collar 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tool holder mounted on a machine tool such as a machining center, a lathe, a grinding machine, etc., and more particularly to a shrink-fit type tool holder for holding a tool by utilizing thermal expansion.

[0002]

2. Description of the Related Art As a shrink fit tool holder (hereinafter simply referred to as a holder), the applicant has filed Japanese Patent Application No. 10-30375.
No. 8 (Japanese Unexamined Patent Application Publication No. 2000-126961), "In a holder having a shank portion detachable from a main shaft of a machine tool and a chuck portion for holding a cutting tool by shrink fitting, the chuck portion is provided with the shank portion. A holder which is formed separately and is made of a material whose coefficient of thermal expansion is larger than the coefficient of thermal expansion of the shank portion; and `` the chuck portion is detachably attached to the shank portion. Tool holder ".

[0003]

SUMMARY OF THE INVENTION The first problem of shrink fitting in "gripping a small-diameter tool" is the size of shrink-fit portion (outer diameter of tool), heating temperature and thermal expansion of shrink-fit portion. Although it is determined by the ratio, when the size of the shrink-fitting portion is reduced, the absolute amount of thermal expansion is reduced, so that a sufficient interference can not be obtained.

Therefore, if the heating temperature is increased, the thermal expansion increases and the interference can be increased. However, if the temperature is excessively increased, tempering occurs, and the hardness of the tool (blade) decreases, and the tool and the blade are hardened. Since the durability of the holder is reduced, the heating temperature is limited.

The interference can be increased by increasing the difference between the coefficient of thermal expansion of the tool and that of the holder, but the tool itself is generally made of high-speed steel (hereinafter, referred to as high-speed steel).
High-speed steel), the holder also needs the required precision and durability, and in order to fulfill the demand, it is limited to stainless steel and tool steel with an austenitic structure, or similar materials, and has a thermal expansion coefficient of There is a limit to increasing the difference.

Further, if a tool made of a sintered alloy of tungsten carbide (hereinafter referred to as a super hard) or a fine ceramic material is employed, the difference in the coefficient of thermal expansion can be increased. Tools are expensive and not widely used.

Under the above circumstances, the outer diameter of the tool is required to be 3 mmφ in order to absorb the dimensional error (tolerance) of the tool recognized in the standard and to obtain a sufficient interference in shrink fitting. Below this, even if the tool can be mounted, it cannot be removed because there is not much temperature difference between the chuck part of the holder and the shank part of the tool.

[0008] The second problem is that the chuck of the holder is detachable from the shank of the tool. There is an advantage that a tool having a different outer diameter can be replaced and gripped within the conditions of having, but the chuck portion having the tapered outer surface corresponding thereto is fitted into the tapered inner surface of the holder having the tapered inner surface, and the chuck portion is formed. A pull bolt is screwed into the female screw at the rear end to make it removable, but the chuck hole diameter must correspond to the shank shaft diameter of the tool, so it is necessary to align both the length and diameter as necessary There is.

[0009] The third problem "correcting the run-out of the tool after gripping" gripping of the tool by the shrink fit method is that the holder expands and contracts evenly from the surroundings, so that it is compared with other gripping methods such as the collet method. Although there is little runout of the shaft center and high accuracy, the shrink fit method has to perform heating and cooling in order to grip the tool, and there is a problem in workability.

The present invention seeks to adopt a tool gripping method which is excellent in accuracy, workability and cost by taking advantage of the advantages of the shrink fitting method and the collet method. Swing occurs.

When the outer diameter of the tool to be gripped is large, the degree of the deflection of the shaft center does not affect the machining accuracy and the service life of the tool is small. However, when the outer diameter is small, the degree is large.

This will be described by taking a two-flute type carbide end mill as an example. The cutting conditions recommended by a tool maker are as follows.
In the case of an end mill of 10 mmφ, it is 52.8 μm.
6.6μ per end mill revolution for end mill of mmφ
m, but if the axis of the end mill oscillates 1.7 μm, it becomes 3.4 μm on both sides of the axis, cutting with only one blade and the other blade idle. 6.6 μm per rotation, ie 6.6 μm with one blade
m, which shortens the life of the end mill or causes breakage.

Fourth problem "Easy setting of tool insertion length"
Regarding the attachment / detachment of the tool in the shrink fitting method, the applicant has proposed “a blade insertion restricting tool used in a shrink fitting device” in Japanese Patent Application No. 9-243851 (Japanese Patent Application Laid-Open No. 11-77443). The contents of this proposal are as follows. As shown in FIGS. 5 and 6, a spring clip arm is gripped on a shank of a tool, the diameter of the spring clip is increased, and the diameter is fitted to the shank of the tool. The holder is attached to a shrink fitting device and inserted into the chuck portion of the heated holder.

As can be seen from the above description, in the above proposal, a measuring instrument such as a caliper must be used each time to set the insertion length, and the setting of the insertion length is not accurate.

In view of the above situation, the present invention firstly makes it possible to grip a small-diameter tool, secondly makes it possible to grip a wide range of tools with the same holder, and thirdly, after gripping. The fourth object is to make it possible to correct the run-out of the tool, and fourthly, to easily set the insertion length of the tool.

[0016]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention forms a shank portion to be fitted into a machine tool on one side and a chuck portion for gripping a shank of a tool by shrink fitting on the other side. In the formed tool holder, a cylindrical sleeve is inserted between the shank of the tool and the chuck portion, a slit and a flange are formed in the sleeve, and the sleeve material is formed of the chuck portion of the tool holder. It is assumed that the thermal expansion coefficient is smaller than the above, and a configuration in which a screw hole is provided on an end surface of the flange is adopted, and a cylindrical main body provided with a grip portion for gripping a shank of a tool at one end as necessary, A cylindrical body having a configuration comprising a plug to be fitted into the main body, or a grip portion for gripping a shank of a tool attached to one end, and a female screw formed on the other inner surface;
A tool insertion length setting jig having a configuration in which a screw shaft formed with a male screw to be screwed with the female screw of the cylindrical main body is screwed is added.

According to the present invention configured as described above, it is possible to grip a small-diameter tool, which has been difficult to grip by shrink fitting, and the gripping range by shrink fitting can be expanded.
Even if gripping is possible, the diameter is relatively small, so strong gripping force can be obtained even in areas where strong gripping force was not obtained, tool deflection can be easily corrected, and tool The insertion length can be easily set.

[0018]

Embodiments of the present invention will now be described with reference to the drawings. As shown in FIGS. 1 and 2, the holder 10 includes a tapered shank portion 11 attached to a machine spindle, a manipulator holding portion 12 engaged with an automatic tool changer, and a chuck portion 13 for gripping a tool shank.
A sleeve 20 provided with a flange 21 at one end as shown in FIG. 3 is interposed between the shank of the tool and the chuck portion 13 of the holder 10 for determining the insertion length of the tool into the sleeve 20. An insertion length setting jig 30 is prepared.

FIG. 3A shows the periphery of the sleeve 20.
And (d), slits 22 are provided at equal intervals parallel to the axis and not to both ends, and a screw hole 23 parallel to the axis is provided on the end face of the flange 21 of the sleeve 20.

The tool 31 (see FIG. 4) and the sleeve 20 are made of a material having a small coefficient of thermal expansion, and the holder 10 is made of a material having a relatively large coefficient of thermal expansion such as austenitic stainless steel or SKD.

A tool 31 is mounted on the holder 10 (see FIG. 4).
First, the insertion length setting jig 30 (hereinafter, referred to as the
The anvil 32 of the jig 30 is set at a desired position, and the tool 31 is pushed into the holding portion 33 of the jig 30 so that the tool 3
The tip of the tool 1 is brought into contact with the anvil 32 and the shank 34 of the tool 31 is gripped by the grip 33.

On the other hand, the holder 10 is set in the shrink-fitting device 40 shown in FIG. 5 and the chuck portion 13 is heated to a set temperature, and the shank 34 of the tool 31 and the sleeve 21 are fixed to the chuck portion 13 together with the sleeve 20. Insert until it abuts against the end face, stop heating, cool and complete shrink fitting.

Here, by inserting slits 22 parallel to the axis of the sleeve 20 and not reaching both ends, when the chuck portion 13 of the holder 10 shrinks after shrink fitting, the shrinking force is efficiently and evenly applied to the shank 34 of the tool 31. Propagated to
It is surely grasped with high accuracy.

Further, even when the dimensional difference between the inner diameter of the sleeve 20 and the outer diameter of the shank 34 of the tool 31 becomes zero, or when the outer diameter of the tool 31 becomes larger than the inner diameter of the sleeve, the insertion may be performed. Tool 31 can be used for sleeve 2
In addition, the work of inserting the tool 31 into the chuck portion 13 of the holder 10 together with the sleeve 20 is facilitated by providing the collar 21 at one end of the sleeve 20.
Positioning is assured.

As shown in FIG. 4A, the insertion length setting jig 30 includes a cylindrical main body 35a having a grip portion 33 for the tool 31 at one end, and a plug 36 fitted into the main body 35a. 4B, a cylindrical main body 35b provided with a grip portion 33 of the tool 31 at one end and a female screw 37 provided therein, and a female screw 3 of the main body 35b as shown in FIG.
7 and a screw shaft 39 having a male screw 38 formed therein. The grip portion 33 has a C-shaped cross section, and uses the elasticity to grip the tool 31. . The end faces (anvils) of the plug 36 and the screw shaft 39 are finished in a plane perpendicular to the shaft.

In the case of FIG. 4 (a), the insertion length is set in a state where the step 36a of the plug 36 is in contact with the end face of the main body 35a, and in the case of FIG. The insertion length is set by the screwing amount of. Therefore, when the micrometer is constituted by the male screw and the female screw, the insertion length can be easily set.

Here, the significance of the use of the jig for setting the insertion length of the tool into the holder is that, in an actual cutting operation, the distance from the gauge line of the spindle of the machine tool to the tip of the tool is input to the storage device of the machine tool. Therefore, the insertion length set by the tool insertion length setting jig has the same significance as the protrusion length from the gauge line of the spindle of the machine tool to the tip of the tool.

When removing the tool 31 from the holder 10,
The insertion length setting jig 30 (see FIG. 4) is fitted over the shank 34 of the tool 31, and the end surface of the grip portion 33 of the insertion length setting jig 30 is set to be several millimeters from the end surface of the sleeve 20. The holder 10 in that state is mounted on the shrink fitting device 40 and heating is started.

When heating is started, the coefficient of thermal expansion of the holder 10 is larger than that of the sleeve 20 or the tool 31, so that the chuck portion 13 of the holder 10 expands in diameter, and the sleeve 20 and the tool 31 are released from the shrink-fit state. The tool 20 and the tool 31 drop by their own weight and stop at the clip 41. In this state, the sleeve 20 and the tool 31 can be removed from the holder 10.

If the tool after shrink fitting has a run-out, the holder 10 is mounted on a measuring instrument such as a machine or a tool setting gauge, and the sleeve is watched by a run-out measuring dial gauge (not shown) while watching the run-out. 20 Tsuba 2
A screw (not shown) is screwed into the screw hole 23 provided on the end surface of the holder 1 and the end surface of the holder 10 is pressed to make correction.

When the cutting work is performed with the bolts attached after the run-out correction, hexagonal bolts are used so that the bolt heads do not protrude. When the bolt is removed and used after the deflection correction, the correction is made in consideration of the return due to the internal stress.

[0032]

As described above, according to the present invention,
First, small-diameter tools can be gripped by shrink-fitting.Also, even if gripping is possible, a relatively small diameter allows a strong gripping force to be obtained even in areas where strong gripping force was not obtained. Second, the same holder can hold a wide range of tools with the same holder, third, the runout of the tool after gripping can be easily corrected, and fourth, the tool insertion length can be easily set. Became.

[Brief description of the drawings]

FIG. 1 is a sectional view of a tool holder according to the present invention.

FIG. 2 is a sectional view of the holder.

FIGS. 3A and 3B are a front view and a bottom view of a sleeve according to the present invention, wherein FIG.
(D) is part 4

FIGS. 4A and 4B show a tool insertion length setting jig according to the present invention; FIG.

FIG. 5 is an explanatory view of a shrink fitting device.

FIG. 6 is a diagram showing a state where a clip is attached to a tool.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Holder 11 Taper shank 12 Manipulator 13 Chuck part 20 Sleeve 21 Flange 22 Slit 23 Screw hole 30 Insertion length setting jig 31 Tool 32 Anvil 33 Gripping part 34 Shank (of tool) 35a, 35b Main body 36 Plug 37 Female screw 38 Male screw 39 Screw Shaft 40 Shrink fitting device 41 Clip

Claims (10)

[Claims] 1. A tool holder having a shank portion to be fitted into a machine tool on one side and a chuck portion for gripping a shank of a tool by shrink fitting on the other side. A shrink-fit type tool holder characterized by having a cylindrical sleeve interposed therebetween. 2. The shrink-fit tool holder according to claim 1, wherein the sleeve is provided with an axial groove. 3. The shrink-fit tool holder according to claim 1, wherein the groove is formed to penetrate in a radial direction. 4. The shrink-fit type tool holder according to claim 1, wherein the groove extends through the groove in the axial direction. 5. The shrink-fit tool holder according to claim 1, wherein the sleeve material is smaller than the thermal expansion coefficient of the chuck member material of the tool holder. 6. The shrink-fit tool holder according to claim 1, wherein a flange is formed at a tip of the sleeve. 7. The shrink-fit tool holder according to claim 1, wherein a screw hole is provided in an end face of the flange. 8. A cylindrical main body provided with a grip for gripping a shank of a tool at one end, and an anvil located on an end surface in the cylindrical main body. The shank of the tool is gripped by the grip. A tool insertion length setting jig for setting a tool insertion length by bringing a cutting edge of the tool into contact with the anvil. 9. A cylindrical main body provided with a grip portion for gripping a shank of a tool at one end, and a plug fitted into the cylindrical main body, wherein the grip portion grips the shank of the tool, A tool insertion length setting jig for setting the insertion length of a tool by bringing the cutting edge of the tool into contact with the anvil of a plug inserted into the main body. 10. A screw shaft provided with a grip portion for gripping a shank of a tool at one end and having a female thread formed on the other inner surface, and a male screw threaded with a female screw of the cylindrical body. A tool insertion length setting jig for setting the insertion length of the tool by holding the shank of the tool in the holding portion and abutting the cutting edge of the tool on the anvil of the screw shaft screwed into the main body. Utensils.