JP2828108B2 - Method and apparatus for extruding sintering material having spiral holes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an extrusion molding method of a sintering material having a spiral hole typified by a so-called oil drilled twist drill having a cutting oil supply hole, and its method. Related to the device.

[Conventional technology]

In the field of materials such as metal materials, cemented carbides, and ceramics, so-called hollow products having holes in the materials are widely used. In the metal materials field, hollow products are manufactured by methods such as machining, hot extrusion, welding, etc.In the cemented carbide and ceramics fields, plastic kneaded products are extruded using a mandrel with a shape corresponding to the hole using extrusion molding method. Extruded from a die to obtain a hollow material.

Among hollow products, hollow products represented by twist drills with oil holes need to have a plurality of holes and be spirally twisted, which makes production difficult and costly as described below. . Generally, a material for a twist drill with an oil hole manufactured from an ingot material is formed by drilling two straight holes in a rod-shaped material by a drill in parallel with an axis and drawing the material until a desired hole diameter is obtained. Are manufactured by mechanically twisting them so that they become predetermined leads.

In the case of powder metallurgy and manufacturing from high-speed tool steel, etc., a straight hole material is obtained by extrusion molding, and after sintering, it is further mechanically twisted similarly to the ingot material to form a spiral hole. Are formed.

JP-A-61-227101 and JP-A-62-240701 disclose
A forming machine and a forming method for obtaining a raw material for a drill having a helical hole by applying a torsion simultaneously with the extrusion of a cemented carbide are disclosed.

The present applicant eliminates the mechanical twisting step in the field of powder metallurgy and proposes a method of torsion extrusion of a sintering material in which a twisted hole is obtained immediately after molding, A torsion extruder and a method for extruding a binder material have been developed, and applications have been filed as JP-A-1-96305 and JP-A-2-34702.

[Problems to be solved by the invention]

As described above, after a material having a straight hole is obtained, a forming method of mechanically twisting to obtain a helical hole requires an expensive torsion device and increases the number of manufacturing steps, resulting in high cost. There is a problem that becomes.

When an article having holes is obtained by an extrusion molding method,
Usually, a mandrel or a pin (hereinafter, referred to as a mandrel) corresponding to the hole of the product is provided in the die hole. When the hole is a spiral shape, the mandrel also needs to have a shape having a spiral portion. In the case of a twist drill with an oil hole, this helical portion has a small diameter.

The present inventors have found the following items from the test results obtained by the above-mentioned torsional extrusion method. That is, since it is ideal that the material to be molded is kneaded as tightly as possible, in the above case, the elongated mandrel receives a strong side pressure from the rigid material to be deformed, and in particular, deforms to lengthen the spiral lead. Therefore, it is difficult to obtain a correct spiral hole, and the abrasion of the mandrel is fast. That is, in the conventional extrusion molding method, the material to be molded is substantially axially fed by the extruder and reaches the die entrance, where the spiral hole die formed in the inside diameter of the die and the inside thereof are arranged. To spiral along the spiral of the mandrel, overcome the internal shear forces,
It is necessary to start spinning, and this shearing force is shared by both the die and the mandrel, but the burden is particularly large for the spiral portion of the small diameter mandrel.

In addition, a molding machine or a molding method in which a spiral hole is obtained by applying a twist at the same time as the extrusion by the extrusion molding method is difficult to handle because the green body to be molded immediately after the extrusion is extruded while rotating. There is an incidental problem that workability is low.

In view of the above problems, an object of the present invention is to provide a method and an apparatus for extruding a sintering material having a helical hole having a correct shape at a low cost with a simple apparatus.

The sintering material referred to in the present invention is a material that becomes a product through a sintering step after molding, and is generally called green.

[Means for solving the problem]

The present invention provides a method for extruding a sintering rod-shaped material having a continuous hole along a spiral having a line parallel to the axis as an axis, wherein the spiral portion has a mandrel having a spiral portion corresponding to the hole. An extrusion method of a sintering material having a helical hole, characterized in that it is rotated around the axis as it moves along the spiral with respect to the material to be extruded, and parallel to the axis. Extruder for pressurizing and supplying a material to be molded, an extrusion die attached to the extruder, A mandrel having a linear spiral portion along a spiral around a line parallel to the axis of the opening in the opening of the die and rotatably provided around the axis, and extrusion of a molding material; Synchronizes the mandrel with its axis An extruder of the material for sintering having a helical hole, characterized in that it consists of a rotary drive which rotates Ri.

[Action]

According to the present invention, the rotational shear of the entire mandrel is reduced by rotating the mandrel to cause the internal shear of the material to be formed to be substantially zero or in the opposite direction. In addition, the present invention is applicable to both with and without a twist groove.

The mandrel of the present invention has a reduced force from the side of the helical portion and is more likely to maintain the correct helical shape.

In addition, since the abrasion caused by receiving the force from the side is prevented, the life due to the abrasion of the mandrel can be extended. Further, the extrusion pressure required for the extruder can be reduced to reduce the wear of the extrusion screw or the like, or to use a more rigid molded object.

〔Example〕

Next, the present invention will be described in detail with reference to the drawings of the embodiments. FIG. 1 is a longitudinal sectional view showing a main part of an apparatus according to an embodiment of the present invention, in which a twist groove of a twist drill is formed at the same time.

A spindle 2 is rotatably provided in the housing 1 through a wall at one end, and a bearing box 3 is fixed to the other end by a bolt 3a. A die case 4 is provided in the bearing box 3 so as to be rotatable via a bearing concentrically with the axis of the spindle 2. On the left end surface of the die case 4 , the case 4 is the same as the spindle 2. A series of synchronous gears 2a, 2b,
Among the 3b, the gear 3b is fixed.

In the die case 4 , a spiral ridge 5a corresponding to the twist groove of the twist drill is formed by an extrusion die 5 engraved at an extrusion opening.
However, it is mounted concentrically with the spindle 2 so as to prevent rotation inside the die case 4 by the pin 5b and to be replaceable by the tightening screw 5c. A mandrel 6 is screwed into a female screw hole at the end of the spindle 2 via a left-hand thread at the head thereof.
The die has a pair of spiral portions whose diameters gradually decrease from the head side along the spiral of the lead, in the same direction as the spiral ridge 5a of the die 4 , with the extension of the axial center as the axis.

The angular relationship between the helical ridge 5a of the extrusion die 5 and the helical portion of the mandrel 6 can be adjusted by disengaging a series of synchronous gears 2a, 2b, 3b and adjusting them again.

The spindle 2 is driven by a control motor (not shown) by a gear 2c.
For example, the rotation angle can be rotated in proportion to the extrusion length of the green extruded from the extrusion die 5 .

 Next, the operation of the above embodiment will be described.

The plastic kneaded body pressurized by an extruder (not shown)
The pressure is fed from the kneading body inlet 1a of the housing 1 and the spindle
2 around the mandrel 6, through the swirling chamber 1b surrounding the spiral direction of the spiral die 5, a die 5 is extruded from the gap between the mandrel 6. The cross-sectional area of the gap between the die 5 and the mandrel 6 is made up of a region that gradually decreases as the material to be extruded advances, and a region behind the region that has a constant cross-sectional shape. Generally, the rate of change of the cross-sectional area of the region where the cross-sectional area becomes gradually smaller is preferably set to be small.

The cross-sectional area of the kneading body inlet 1a of the housing is large corresponding to that of the extruder. In contrast, the cross-sectional area immediately after the inlet between the die 5 and the mandrel 6 depends on the target drill diameter, but is generally sufficiently small. .

In the conventional method in which the die 5 and the mandrel 6 are not rotated, the molded body is guided by the spiral projection 5a and the spiral portion of the mandrel 6 immediately after the entrance of the die 5 and the mandrel 6, and starts rotating. Die 5 and mandrel 6
Internal shearing of the kneaded material at the inlet portion with the upstream portion occurs. As a result, a side pressure acts on the spiral portion of the mandrel 6 and the spiral ridge 5 as a reaction of the shearing force. In particular, the side pressure acting on the spiral portion of the mandrel 6 causes the shape of the thin linear portion to be long. Deforms as it forms and promotes wear.

In the present invention, the die 5 and the mandrel 6 are rotated in a direction opposite to the rotation of the extrusion of the material to be formed, so that the internal shear of the kneaded material at the inlet of the die 5 and the mandrel 6 is substantially zero. . As a result, the spiral portion of the mandrel 6 does not receive the side pressure and is prevented from being deformed, and excessive wear due to the side pressure is also prevented. In addition, since the energy loss due to the internal shearing of the kneaded body is eliminated, and the pressure loss of this portion is reduced, the required pressure for feeding can be reduced or the kneaded body can be kneaded more firmly.

In the above case, the molded object at the exit of the die 5 and the mandrel 6 hardly rotates, or
By the adjustment, it is possible to rotate in any direction at an extremely low speed, and subsequent handling can be facilitated.

In the above embodiment, the case where the spiral ridge 5a corresponding to the twist groove is provided in the die 5 has been described, but the present invention does not relate to the existence thereof. In the absence of this, a mechanism for rotating the die 5 can be omitted.

The above-described embodiment is characterized in that the root portion of the spiral portion as the mandrel 6 has a large diameter so as to increase the strength against bending and further increase the shape stability. It has been confirmed that creation of complicated shapes such as the mandrel 6 and the die 5 can be easily manufactured by electric discharge machining using a plate-shaped electrode and appropriate manual finishing.

Next, by the above-mentioned apparatus (the die 5 does not have the spiral ridge 5a), C 1.58% corresponding to AISI T15, Si 0.4
5%, Mn 0.38%, Cr 3.98%, W 12.21%, Mo 1.05%, V
Using a water atomized prealloyed powder consisting of 4.86%, 4.99% Co, balance iron and unavoidable impurities, a rod-shaped material for an oil hole drill having a helical hole was formed. The raw material powder used had an average particle size of 44 μm, which was dry-pulverized to an average particle size of 18 μm. Weight of this powder 100
Then, methyl cellulose, water, microcrystalline wax, stearic acid emulsion, and glycerin were combined and kneaded at a ratio of 13 to obtain a plastic kneaded product.

The kneaded body is extruded from the die 5 by driving an extruder (not shown), and the speed is detected by a sensor (not shown) provided behind the die 5 , and by controlling a motor (not shown), the mandrel passes through the spindle 2. 6 was rotated to extrude a rod-shaped material having a spiral hole to obtain a molded body as shown in FIG. Thereafter, the molded body was dried and then sintered after removing the binder, but no abnormality was observed in each step.

In the above embodiment, the helical hole is made concentric with the axis of the rod material to be molded. However, it is clear from the mechanism that the present invention is not necessarily limited to the concentric one.

〔The invention's effect〕

As described above, the present invention facilitates the production of a material for sintering having a spiral hole directly by powder metallurgy, which has not been practically used in the past, and involves a twisting process which is currently in practical use. This realizes a significant cost reduction as compared with the case of (1).

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an essential part of an embodiment of the extrusion molding apparatus of the present invention, and FIG. 2 is a view showing a product according to the above embodiment. 1 : Housing, 1a: inlet, 1b: spiral chamber, 2 : spindle, 2a: synchronous gear, 2b: synchronous gear, 2c: gear, 3 : bearing housing, 3a: bolt, 3b: synchronous gear, 4 : die case, 5 : extrusion die, 5a: spiral ridge, 5b: pin, 5c: tightening screw, 6: mandrel

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) B22F 3/00-5/12 B23P 15/32 B30B 11/22 B28B 3/20

Claims (2)

(57) [Claims] 1. A method for extruding a sintering rod-shaped material having holes continuous along a helix having a line parallel to the axis as an axis, wherein a mandrel having a helix corresponding to the hole is provided by the helix. A method for extruding a sintering material having a helical hole, wherein the material is rotated about the axis as the material moves along the spiral with respect to the material to be extruded. 2. An extruder for extruding and supplying a material to be molded in a sintering rod-shaped material extruding apparatus having a hole continuous along a spiral having a line parallel to the axis as an axis. An extrusion die attached to the extrusion die, a mandrel provided inside the opening of the extrusion die and having a spiral portion along a spiral having a line parallel to the axis of the opening as an axis, and rotatably provided around the axis; And an apparatus for extruding a sintering material having a helical hole, the apparatus comprising a rotary drive for rotating the mandrel around its axis in synchronization with the extruding movement of the material to be molded.