JPH03107401A - Method and apparatus for executing extrusion-compacting of raw material for sintering having spiral hole - Google Patents

Abstract

PURPOSE:To easily execute extrusion-compacting of raw material for sintering having spiral hole at a low cost by pressurizing material to be compacted, extruding, rotating a mandrel around parallel line to an axis and moving the spiral part thereof along spiral. CONSTITUTION:In a valute chamber 1b in a hausing 1 in an extrusion-compacting apparatus, the material to be compacted of kneaded plastic material is fed under pressure from an inlet 1a. This material to be compacted is fed by rotation of a spindle 2 through a gear 2c and extruded from gap between a die 5 and the mandrel 6. The above extruding die 5 is supported as rotatable with a bearing box 3 and synchronously rotated with the spindle 2 through synchronizing gears 2a, 2b, 3b, etc. to make internal sharing in the material to compacted almost zero. On the other hand, the mandrel 6 fixed at tip part of the spindle 2 has spiral projection 5a and rotates around the parallel line to the axis so as to move along the spiral to the material to be compacted subjected to the above extruding movement. By this method, the extrusion-compacting is easily executed to the bar-like raw material for sintering having spiral hole without receiving side pressure to the above spiral projection 5a part.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an extrusion molding method for a sintering material having a spiral hole, typified by a so-called twist drill with an oil hole, which has a cutting oil supply hole. Regarding equipment.

[Conventional technology]

In the field of materials such as metal materials, cemented carbide, and ceramics,
So-called hollow products with holes in the material are widely used. In the metal materials field, hollow products are manufactured using methods such as machining, hot extrusion, and welding, while in the cemented carbide and ceramics fields, extrusion molding methods are used to manufacture plastic mixed bodies with mandrels shaped to correspond to the holes. Hollow holes are obtained by extrusion from a die.

Among hollow products, hollow products such as oil hole twist drills have multiple holes and need to be twisted in a spiral shape, making them difficult and costly to manufacture as described below. It also becomes more expensive. Generally, the material for twist drills, which is manufactured by melting and drilling, is made by drilling two straight holes parallel to the axis of a rod-shaped moon with a drill, and drilling it until the desired hole diameter is achieved. It is manufactured by mechanically twisting the drawn material so that the holes form a predetermined lead.

Powder metallurgy at high speed - When manufacturing from molded steel, etc., a straight material is obtained by extrusion, sintered, and then mechanically twisted to form spiral holes in the same way as the melted material. A method of forming is being used.

JP-A-61-227101, JP-A-61-24070
Publication No. 1 discloses a molding machine and a molding method for obtaining a material for a drill having a spiral hole by extruding and simultaneously twisting a cemented carbide.

In the field of powder metallurgy, the applicant has proposed a method for twist extrusion of a sintering material that eliminates the mechanical twisting step and that allows twisted holes to be obtained immediately after forming, and a sintering method that allows twisted holes and twisted grooves to be obtained. Developed a torsional extrusion device and extrusion method for knotted materials, and published Japanese Patent Application Laid-open No. 96305 and Patent Application No. 1983-1.
The application was filed as No. 82994.

[Problem to be solved by the invention]

The method described above, in which a material with straight holes is obtained and then mechanically twisted to obtain spiral holes, requires an expensive twisting device and requires many manufacturing steps, resulting in high costs. There is a problem that.

When an article with holes is to be obtained by extrusion molding, a mandrel or bottle (hereinafter referred to as mandrel) corresponding to the hole in the product is usually provided in the die hole, but if the hole is spiral-shaped, the mandrel also has a spiral portion. It is necessary to have a shape that has the following. In the case of a twist drill with an oil hole, this spiral portion has a small diameter.

The present inventors discovered the following from the test results using the above-mentioned twist extrusion method. That is, since it is ideal to knead the material to be formed as hard as possible, in the above case, the elongated mandrel receives strong lateral pressure from the hardened material to be formed.
In particular, it is subject to deformation that lengthens the helical lead, making it difficult to obtain the correct helical hole, and also causing rapid wear of the mandrel.

That is, in the conventional extrusion molding method, the phase to be molded is force-fed by an extruder in the axial direction to reach the die cavity, where it is formed into a spiral hole formed in the inner diameter of the die and is disposed within the inner diameter. In order for the mandrel to move spirally along the helical part, it is necessary to overcome the internal shearing force and start rotating, and this shearing force is borne by both the die and the mandrel. This is a heavy burden for the spiral portion of a small-diameter mandrel.

In addition, extrusion molding machines and molding methods that create spiral holes while applying twist at the same time as extrusion are difficult to handle because the molded object in a green state immediately after extrusion is extruded while rotating. There is an additional problem of low workability.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide a method and apparatus for extrusion-molding a sintering material having spiral holes of the correct shape at low cost using a simple device.

The sintering material used in the present invention is a material that is formed into a product through a sintering process after molding, and is generally called green.

[Means to solve the problem]

The present invention provides a method for extrusion molding a rod-shaped material for sintering having holes continuous along a spiral whose axis is a line parallel to the axis, in which a mandrel having a spiral portion corresponding to the hole is formed so that the spiral portion is A method for extruding a sintering material having a spiral hole, the method comprising rotating a phase to be extruded around the axis so as to move along a spiral, and parallel to the axis. An extrusion molding apparatus for a rod-shaped material for sintering having continuous holes along a spiral with a line as an axis includes an extruder that pressurizes and supplies a phase to be molded, an extrusion die attached to the extruder, and an extrusion die attached to the extruder. A mandrel having a linear spiral part along a spiral whose axis is a line parallel to the axis of the opening in the die and rotatable around the axis, and extrusion of a material to be formed. This compact press-forming device for a sintering material having a spiral hole is characterized by comprising a rotary drive device that rotates the mandrel around its axis in synchronization with the motion.

[Effect]

The present invention reduces the rotational force load on the entire mandrel by driving the mandrel to rotate so that the internal shear of the material to be formed is almost zero or causes internal shear in the opposite direction. Furthermore, the present invention is applicable to both with and without helical grooves.

The mandrel of the present invention has reduced lateral forces on its helical portion, making it easier to maintain the correct helical shape.

Furthermore, by preventing wear caused by receiving this lateral force, it is possible to extend the life of the mandrel due to wear. Furthermore, it becomes possible to reduce the extrusion pressure required for the extruder, thereby reducing wear on the extrusion screw, etc., or to use a harder molded object.

〔Example〕

The present invention will be described in detail based on the drawings of embodiments. 1st
The figure shows the main parts of an apparatus according to an embodiment of the present invention, and is a longitudinal cross-sectional view of the apparatus for simultaneously forming twisted grooves of a twist drill.

A spindle 2 is rotatably provided in the housing 1 passing through a wall surface at one end, and a bearing box 3 is fixed to the other end with bolts 3a. A die case 4 is provided in the bearing box 3 so as to be concentric with the axis of the spindle 2 and rotatable via a bearing. A series of synchronous gears 2a, 2 rotate in the same direction and at the same speed.
Of gears b and 3b, gear 3b is fixed.

Inside the die case 4, there is an extrusion die 5 having an extrusion opening carved with a spiral protrusion 5a corresponding to the helical groove of the twist drill.
is mounted concentrically with the spindle 2 to prevent rotation within the die case 4 with a pin 5b and to be replaceable with a tightening screw 5C. A mandrel 6 is screwed into the female threaded hole at the end of the spindle 2 through a left-hand thread on its head, and the mandrel 6 has a foot part with an extension line of the axis of the spindle 2 as its axis, and a die. 4 spiral protrusion 5
It has a pair of spiral portions that extend in the same direction as a and along the spiral of the lead, and whose diameter gradually decreases from one side of the head.

The angular relationship between the helical protrusion 5a of the extrusion die 5 and the helical portion of the mandrel 6 is a series of synchronous gears 2a.

Adjustments can be made by disengaging 2b and 3b, adjusting them, and then re-engaging them.

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

The operation of the above embodiment will now be explained.

The plastic mixed material pressurized by an extruder (not shown) is fed under pressure from the kneading rod inlet 1a of the housing 1, and is spirally surrounded around the spindle 2 in the spiral direction of the mandrel 6 and die 5 in a spiral chamber]-1) It is then extruded from the gap between the die 5 and the mandrel 6. The cross-sectional area of the gap between the die 5 and the mandrel 6 consists of a region that gradually becomes smaller as the material to be extruded advances, and a region behind that region that remains in the perfect cross-sectional shape. As the cross-sectional area becomes gradually smaller, the rate of change in the cross-sectional area of the region should generally be set to a small value.

The cross-sectional area of the mixer inlet 1a of the housing is large corresponding to that of the extruder, whereas the cross-sectional area immediately after the inlet between the die 5 and the mandrel 6 is generally sufficiently small, although it depends on the target drill diameter. .

In the conventional method in which the die 5 and mandrel 6 are not rotated, the object to be molded immediately after the entrance of the die 5 and mandrel 6 is guided by the spiral protrusion 5a and the helical portion of the mandrel 6 and begins to rotate. Along with this, die 5, mandrel 6
Internal shear occurs between the hybrid body to be molded in the artificial part and its upstream part. As a result, as a reaction to the shear force, the mandrel 6
Lateral pressure acts on the spiral portion of the mandrel 6 and the spiral protrusion 5a, and in particular, the lateral pressure acting on the spiral portion of the mandrel 6 deforms the shape of the thin linear core portion into a long lead shape, and also prevents wear. Facilitate.

In the present invention, the die 5 and the mandrel 6 are rotated in the direction opposite to the rotation of the extrusion of the material to be formed to such an extent that the internal shear of the mixed wire to be formed at the entrance of the die 5 and the mandrel 6 is reduced to almost zero. . This prevents the helical portion of the mandrel 6 from receiving lateral pressure, thereby preventing deformation, and also prevents excessive wear due to lateral pressure. In addition, there is no energy loss due to internal shearing in the mixed body to be formed, which reduces the pressure loss in the core, making it possible to reduce the required pumping pressure or to make the mixed body more rigid.

Furthermore, in the case indicated by "-", the molded object at the outlet of the die 5 and mandrel 6 is in a state where it hardly rotates, or it is possible to rotate it in any direction at a very low speed by adjustment. This makes it possible to facilitate subsequent handling.

Although the above-mentioned embodiment describes the case where the die 5 is provided with the spiral protrusion 5a corresponding to the helical groove, the present invention is not concerned with the presence or absence of the helical protrusion 5a. In the absence of this, the mechanism for rotating the die 5 can be omitted.

The second embodiment is characterized in that the root part of the spiral portion of the mandrel 6 has a large diameter to increase the strength for bending and to further improve the shape stability. It has been confirmed that complex shapes such as the mandrel 6 and the die 5 can be easily produced by electrical discharge machining using a plate-shaped electrode and appropriate manual finishing.

Next, using the above-mentioned device (however, the die 5 does not have the spiral protrusion 5a), C1,5 equivalent to Al5I T15 is
8%, SiO, 45%, Mn 0.38%, Cr 3.9
8%, W12.21%, Mo 1.05%, V 4.8
A water atomized prealloyed powder consisting of 6% Go, 4.99% Go, balance iron and unavoidable impurities was used to form a bar for an oil hole drill having a spiral hole. The average particle size of the raw material powder used was 44 μm, which was dry-pulverized to have an average particle size of 18 μm. Methyl cellulose, water, microcrystalline wax, stearic acid emulsion, and glycerin were mixed and kneaded at a ratio of 13 parts per 100 parts by weight of this powder to obtain a plastic kneaded body.

This crosstalk is extruded from the die 5 by driving an extruder (not shown), its speed is detected by a sensor (not shown) installed behind the die 5, and by controlling a motor (not shown), it is passed through the spindle 2 to the mandrel. Rotate 6,
A rod-shaped rod having spiral holes was extruded to obtain a molded body as shown in FIG. 2. Thereafter, the molded object was dried, the binder was removed, and then sintered, but no abnormality was observed in each step.

In the second embodiment, the spiral hole is concentric with the axis of the mixed wire to be molded, but it is clear that the present invention is not necessarily limited to a concentric hole.

〔Effect of the invention〕

As described above, the present invention facilitates the production of sintering materials having direct spiral holes using powder metallurgy, which has not been fully put into practical use in the past, and which involves twisting, which is currently in practical use. This results in a significant cost reduction compared to the previous model.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing a main part of an embodiment of an extrusion molding apparatus of the present invention, and FIG. 2 is a diagram showing a product according to the above embodiment. 1: housing, la: inlet, 1b: swirl chamber, 2 spindle, 2a: synchronous gear, 2b = synchronous gear, 2c: gear, 3: bearing box, 3a: bolt, 31) bisynchronous gear, 4:
Die case, 5: Extrusion die, 5a: Spiral protrusion, 5b:
Pin, 5C: Tighten screw, 6: Mandrel

Claims (1)

[Scope of Claims] 1. In an extrusion molding method for a rod-shaped material for sintering having holes continuous along a spiral whose axis is a line parallel to the axis, a mandrel having a spiral portion corresponding to the hole is 1. A method for extruding a sintering material having a spiral hole, characterized in that the spiral portion is rotated about the axis of the material to be extruded so that the material moves along the spiral. 2. In an extrusion molding device for a rod-shaped material for sintering having holes continuous along a spiral whose axis is parallel to the axis, an extruder that pressurizes and supplies the material to be molded, an extruder attached to the extruder An extrusion die, a mandrel having a helical portion in the opening of the extrusion die that follows a spiral whose axis is a line parallel to the axis of the opening, and rotatable around the axis, and a material to be formed. 1. An extrusion molding device for a sintering material having a spiral hole, the device comprising a rotational drive device that rotates the mandrel around its axis in synchronization with the extrusion movement of the mandrel.