JPS59102547A - Device for holding tool - Google Patents

Abstract

PURPOSE:To reduce the ratio of wear and to avoid seizure even in heavy cutting with a tool holder inserted in the spindle of a machine tool, by providing a contact part of a vanadium carbide or alumina between the tool holder and the spindle. CONSTITUTION:Alumina powder of 0.5 to 2mu in grain size is mixed with 3 to 5% by weight of a high-molecular binder. The mixed material is molded under pressure of 500 to 2,000kg/cm<2> and then baked at a temperature of 1,500 to 1,600 deg.C to obtain a sintered alumina element. This element is fitted as an alumina sleeve 22 in the tapered part of a spindle 21 by screws 23.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tool holding device for a machine tool, and more particularly, to a tool holding device that reduces the wear caused by a tool having a fitting part or a contact part accompanied by vibration at t#.

Vibration wear that occurs in the rotating and vibrating parts of general machinery is surface damage that occurs when minute tangential vibrations are applied between two solid bodies that are in contact with each other. It is necessary to apply a strong force to the surface or apply lubricating oil to reduce the coefficient of friction. However, if we take a machine tool's machining center or side boring machine as an example, the clamping force between the tool holder and the tapered surface of the spindle is applied by the Solstud built into the spindle, but the space is limited. I controlled it. For this reason, when heavy cutting is performed for a long time using a rough figure/gravity cutter, end mill cutter, etc., the shank surfaces of the tool holder and spindle will wear out due to cutting vibrations, and the two surfaces will adhere, causing the tool to be removed after cutting. It was sometimes difficult to extract the Therefore, lubricating oil is sometimes applied between the two surfaces, but the current situation is that the lubricating oil is coated with cutting powder and is not a viable solution.

Therefore, in order to understand the phenomenon of vibration wear, the inventor conducted a test using a vibration wear tester shown in FIG. In the figure, a plate-shaped test piece 11 is fixed to a tension shaft 19 via bolts, and is opposed to a test piece 14 attached to the test piece INC supporter 12 and pressed by a pole 13. The supporter 12 is pressed by a ring 15 and a port 16 attached to a fixing member (not shown). When a hydraulic mechanism that has a servo mechanism (not shown) and can adjust the amount of displacement repeatedly applies a compression load to the shaft 17, the tension shaft 19, which is attached to @17 by the bolt 18, expands and contracts. Both test pieces 1] and 14 reciprocate over a minute distance and wear out. Table 1 shows the results when the swing width and pressing load were varied using carburized and quenched steel such as 8CM435 as the material for both test pieces 1 and 14.

Table 1 Specific wear amount The specific wear amount refers to the wear volume of specimens 11 and 14 subjected to vibration wear. ) is the value divided by As shown in Table 1, vibration wear occurs when a small distance is displaced under a load. Table 2 shows the specific wear amount under amplitude and vertical load of 100 mm for various combinations of materials. Wear is occurring.

Table 2 Specific Wear Amount of Each Material This was developed from the viewpoint of the present invention, and its purpose is to provide a tool holding device that combines a tool holder and a spindle with a small amount of wear.

An embodiment of the present invention will be described below. The tool holder and the spindle are each made of air-hardenable tool steel, and both are suspended in a bath molten salt (Na2B40□) of vanadium or 7-erononadium powder, and the temperature of the molten salt is raised to 950 or higher. 2 to 1 inside stored at 1100℃
Perform air quenching for 0 hours. On the surface layer of both surfaces exposed to K, 5 to 15 μm of fake sodium carbide is formed, and its hardness reaches 3,000 to 4,000 on the Vickers scale.

As another example, 3 to 5 parts by weight of a polymer indulator is added to alumina powder of about 0.5 to 2 μm, and this is molded at a pressing force of 500 to 2000 Kt/α2, and then 1500 to 1600 Kt/α2 is applied. As shown in FIG. 2, the sintered alumina part fired at 0.degree.

Similarly, although not shown, an alumina sleeve is also attached to the tapered portion of the tool holder. Note that the tool holder and the main @21 may be made of alumina compact.

A specific example will be explained below.

Example 1 The material of the tool holder and spindle is SKDl], and the following pretreatment is performed on it. Forged material → Annealing (800℃ 3 hours) →
Machining → Annealing (600℃ 1 hour) → Quenching (1050℃
] → Tempering (250℃ → Grinding process) This material was held in a bath molten salt (Na2B40□) in which vanadium powder was suspended at a heating temperature of 1050℃ for 5 hours, and then removed from the bath and blown with nitrogen gas. Boxwood forced cooling base material (5KDII)
was quenched. The thickness of the generated layer at this time was 10μ, the hardness of the generated layer was 3200 on the Pinkers hardness, and the hardness of the base material was H.
It was V580. When this was tested using the vibration abrasion tester shown in Figure 1, the specific wear amount was 0.5 to 0.7 x 10-
71112/9, which is almost an order of magnitude smaller than in Table 2 above.

Example 2 Stearic acid was added by weight to 0.5 to 1μ alumina powder, and the sintered alumina material was molded at a pressure of 1000Kg/cIIL2 and then fired at 1500°C. Grind it into the shape and attach it to the main shaft 21. Similarly, the tool holder (not shown)
An alumina sleeve was attached to the tapered part. The hardness at this time was 1800 on the Vikalas hardness. When this was tested using the vibration wear tester shown in Figure 1, the specific wear amount was 0.
．． It was 3 to 0.5×IQ-7w2/Kg.

As described above, the tool holding device of the present invention is constructed by treating the contact portion between the tool holder and the main shaft of the machine tool with vanadium carbide or alumina.

Therefore, the formed layer of nomanadium carbide or alumina is extremely hard, with a hardness of 1800 to 3000 on the Pinkers hardness, and therefore the specific wear amount measured by a gestational wear tester is one order of magnitude smaller than that of conventional general materials.

As a result of this effect, even when heavy cutting is performed with the tool holder inserted into the spindle, there are no accidents caused by condensation. Further, since the above-mentioned generated layer does not coexist with the iron-based material and the surface is in a dry state, the present invention has the effect that chips and dirt can easily fall off during cutting, no matter how many layers there are.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a vibration abrasion tester, and FIG. 2 is a sectional view of an embodiment of the present invention. 2] Main shaft, etc. Alumina sleeve.

Claims (1)

[Claims] 1) A tool holding member whose contact portion between the tool holder and the main shaft of the machine tool is treated with vanadium carbide or alumina. 2) Both the tool holder and the main shaft of the machine tool are constructed of air-hardenable tool steel. A patent characterized in that a vanadium carbide layer is formed at the contact area between the tool boulder and the spindle by treating the tool steel in a molten salt in which powder of vanadium or ferrovanadium is suspended. A tool holding device according to claim 1. 3) The contact parts or all of the tool holder and the main spindle of the machine tool are formed by molding 3 to 5% by weight of a polymer binder into 0.5 to 2μ alumina powder and then firing at 1500 to 1600°C. A tool holding device according to claim 1.