JPH06293902A - Sintering material having spiral small hole and its rotation-controlled extrusionmolding method - Google Patents

Abstract

PURPOSE:To easily obtain a sintering material having a highly precise spiral small hole with a desired lead value by restricting the periphery of a compact leaving a die having a spiral pin and revolving the compact on its axis at a speed conforming to the extrusion rate of the compact. CONSTITUTION:A plastic kneaded body is charged into an extruder 1, pressed, twisted along the inner recess and protrusion 2a and 2b of the die 2 having a spiral pin 3 and extruded. The periphery of the extrudate is restricted by a rotating die 5, mounted freely rotatably on the outlet of the die 2, and a sintering material having a spiral small hole with the desired lead value is obtained. The obtained material has a small hole enhanced in spiral precision, and a sintering material having a spiral small hole with the error in the angle between the spiral and the axis of the small hole kept within + or -2.5 deg. is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sintered material having cutting oil supply holes, which has small holes spirally connected around an axis represented by a so-called oil drill twist drill, and an extrusion molding method thereof. .

[0002]

Hollow products are widely manufactured in the field of powder metallurgy materials, ceramics and the like. Among them, the extrusion molding method is a method of extruding a plastic kneaded body from a die having a mandrel having a shape corresponding to the hollow portion, a pin, etc. to obtain a hollow material, which is suitable for producing a long product having the same cross-sectional shape. There is. Among hollow products, hollow products represented by twist drills with oil holes require that the hollow holes be twisted in a spiral pattern around the axis, and the manufacturing method described below is adopted. ing. Materials for twist drills with oil holes, which are manufactured from rod-shaped starting materials made of ingot or powder, have a pair of holes drilled in the rod with a drill parallel to the axis, and the material with the desired hole diameter. It is manufactured by mechanically twisting the drawn material so that the small holes have a predetermined lead.

In the case of a powder metallurgical sintered material which is manufactured from high speed tool steel or the like, a material for a straight hole is obtained by an extrusion molding method, sintered, and then mechanically mechanically similar to the rod-shaped starting material. A method of applying a twist to form a spiral hole is used. In addition, JP-A-61-227101 and JP-A-1
Japanese Patent Laid-Open No. 156405 discloses a molding method for obtaining a molded product for a drill having a spiral small hole by extruding a plastic kneaded product made of a raw material powder and imparting a twist at the same time.

The applicant of the present invention has proposed a method for twisting and extruding a sintering material which can immediately obtain a twist groove for discharging chips as it is molded, and a twist extrusion of a sintering material which can obtain a twist hole and a twist groove. An apparatus and an extrusion method were developed and applied as Japanese Patent Application Laid-Open No. 1-96305 and Japanese Patent Application No. 63-182994. However, it is generally difficult to avoid the occurrence of bending during sintering, and a sintered material having a twist groove for discharging chips when straightening the bending is liable to be disadvantageous with respect to straightening accuracy and breakage.
Many do not have twist grooves.

[0005]

As described above, the method of obtaining a spiral small hole by mechanically twisting it after obtaining the material having the small hole of the straight, requires an expensive twisting device. Since it is necessary and the number of manufacturing processes increases, there is a problem that the cost increases. In the production of these twist drills, in the case of a material without a twist groove for discharging chips, it is necessary to form a twist groove by cutting or grinding, and in this case, the material is as long as possible from the viewpoint of production efficiency. It is desirable to have a shaku. However, if there is an error in the position of the small hole, that is, the angle of the small hole with respect to the axis or the lead, there is a risk that the small hole opens in the twist groove. A first object of the present invention is to provide a sintered material having spiral small holes with high accuracy of small hole position.

Further, recently, with the progress of the handling technique and the sintering technique of the plastic kneaded body, it has become possible to keep the shrinkage rate during sintering within a narrow range. Therefore, in order to obtain a sintered body with high dimensional accuracy, improving the accuracy of the green body is a major issue. A method for obtaining spiral small holes at the same time as extrusion molding is disclosed in JP-A-61-2721.
No. 01, Japanese Patent Laid-Open No. 1-156405, these methods are methods of forming a twist groove on the inner circumference of the die, thereby imparting a rotational tendency to the material to be molded. However, in these methods, the material to be extruded at the center of the die opening cannot move along the twist groove on the inner circumference of the mold because the force to move straight is exerted. The lead of the spiral small hole does not match the lead of the twist groove on the inner circumference of the die and is larger than the lead of the twist groove on the inner circumference of the die, and the amount of error depends on the kneading body and extrusion speed. There is a problem that it greatly fluctuates depending on the condition of.

Further, Japanese Patent Application Laid-Open No. 1-96305 and Japanese Patent Application No.
In No. 3-182994, a twist fin is arranged in the central portion on the upstream side of the inner cavity of the die, and the twisted groove on the inner circumference of the die is used to impart a rotational tendency to the material to be molded. Since there is a space from the inner circumference of the die, the material to be molded tends to go straight during this interval, and thus sufficient twist cannot be imparted. Therefore, the lead of the spiral small hole of the formed sintering material is still larger than the lead of the spiral groove on the inner circumference of the die. In addition, there is a proposal to rotate the pin corresponding to the die or the spiral hole in order to suppress the error or variation in the lead of the extruded material, but while sealing the high pressure of the kneading body, these can be rotated. It is practically impossible.

In view of the above problems, the second object of the present invention is to perform extrusion molding of a sintering material by the powder metallurgy method, in which the amount of twist or the accuracy of the lead is high. An object of the present invention is to provide an extrusion method capable of obtaining a binding material. The term "sintering material" as used in the present invention means a material for a sintered member manufactured through a sintering process after molding.

[0009]

DISCLOSURE OF THE INVENTION The inventors of the present invention have conducted various studies in order to obtain a sintering raw material having highly accurate spiral small holes of a lead, and as a result, have been extruded from a die opening. By providing a means for gripping and rotating the outer peripheral surface of the material to be molded, the rotation of the material to be molded, which tends to be insufficient as described above, is compensated for, or the shortage is taken into consideration, and the excessive amount of the extrusion die produced is used. I came up with the idea of restricting rotation, such as suppressing rotation. This can avoid the problem of sealing the kneaded body. Further, by obtaining the means for regulating the rotation, by adding an extrusion length measuring device, a rotation angle measuring device, etc., closed loop and feedback control becomes possible. By adopting this control method and by reducing the fluctuation range of the sintering shrinkage rate as described above, it becomes possible to obtain a sintered material with a high positional accuracy of small holes which has not been obtained in the past.

That is, the present invention relates to a rod-shaped powder sintered material having small holes spirally connected to each other around an axis, the small holes having a length of at least 300 mm excluding both ends of the rod-shaped material. The angle error between the spiral and the small hole around the axis is within ± 3.6 ° when it is assumed that the small lead follows the spiral of the constant lead. In a method of extruding a kneading body into a rod shape having small holes spirally connected around an axis, the plastic kneading body is extruded through a die having a pin corresponding to the small holes in the opening. A rotation-regulated extrusion molding method, which comprises a step and a second step of restraining the rotation of the molded material by restraining the molded material extruded by the outer periphery thereof, and the rotation around the axis. Pressing the sintering material with small holes spirally connected to each other In the extrusion molding method, the first step of extruding the plastic kneaded material as a raw material through a die having spirally continuous irregularities on the inner peripheral surface and having pins corresponding to the small holes in the openings. And a second step by a rotation restricting means for restricting the rotation of the molded material by restraining the molded material extruded by the outer periphery thereof, and the extrusion length of the molded material after the second step. The extrusion length measuring device for measuring the height, the rotation angle measuring device for measuring the rotation angle of the material to be molded after the second step, and the measurement values of both the measuring devices are input, and these are preset. Sintering having spiral small holes, characterized in that the position of the small hole with respect to the axis is controlled by a control device for controlling the rotation angle of the rotation restricting means in comparison with the value. Of material rotation It is out molding method.

[0011]

The sintered body of the first invention of the present application has small holes with high spiral precision. For this reason, when performing cutting dust discharge groove processing of the drill by grinding, cutting, etc., this processing is long,
Moreover, since the positioning can be performed easily on the processing machine, it is possible to improve the efficiency of this processing. Next, according to the method invention of the present application, when the material to be molded exits from the die, the outer periphery of the material is constrained to rotate around the axis of the material to be molded at a speed matching the extrusion speed of the material to be molded. By letting
A sintering material having spiral small holes with a desired lead value can be easily obtained.

In the second invention of the present application, by providing the inner peripheral surface of the die with spirally continuous irregularities, the workpiece material is extruded while being given a rotational tendency by the spiral irregularities of the die,
Furthermore, the rotation is restricted by the outer circumference and the rotation is regulated to form the desired lead, but since the material to be formed is pre-twisted due to the unevenness of the die, the rotational force to be given by the restraining means is small. Well, it is possible to reduce deformation and slip due to restraint, and by providing the protrusion with a rotation speed that matches the extrusion speed of the molded body, it is easy to have accurate lead spiral small holes, and grinding It is possible to obtain a sintered material with a small outer diameter finishing cost due to the above. Further, in the second invention of the present application, as a method of restraining the molded material in the second step of restricting the rotation of the molded material, the tip of the peripheral surface of the molded material is bited into the shaft of the molded material. A plurality of protrusions that rotate around the center is desirable because it has a simple structure and has little resistance to the movement of the material to be molded in the extrusion direction.

Furthermore, by obtaining the means for restricting the rotation of the material to be molded, it becomes possible to construct a closed loop automatic control system. The third invention of the present application shows the configuration of the closed-loop automatic control system, but the components other than the rotation restricting means have no particular feature. However, by completing this closed loop, it became possible to manufacture a green with extremely high spiral precision, which made it possible to obtain a highly accurate sintered body. That is, in combination with the fact that the kneaded body handling technology and the progress of the sintering technology have made it possible to control the shrinkage rate associated with sintering within a narrow range as described above,
A highly accurate sintered body can be obtained.

As a restraint means for restricting the rotation of the object to be molded, it is appropriate to use fins or spatula-shaped projections continuous in the axial direction, which will be described later in Examples, and to be concentric with the material to be molded. With a large number of discs rotatably supported around the tangent to the shaft or discs for the rotating piece of the roulette (these are designed to bite the tip or the periphery of the outer peripheral surface of the material to be molded) ), And a large number of caterpillar-shaped rolling elements may be arranged around the material to be molded.

[0015]

EXAMPLES The present invention will be described in detail with reference to Examples. Figure 1
FIG. 6 is a cross-sectional view showing a main part of an apparatus that has been subjected to rotation-regulated extrusion molding according to the second invention of the present application. The plastic kneaded body is pressed by an extruder 1 including a cylinder 1a and a screw 1b. At the outlet of the extruder 1, there is a spiral concavo-convex pattern on the inner peripheral surface, and the valley diameter of the valley section 2a of this concavo-convex section is 14.
6 mm, the inner diameter of the peak portion 2b is 12.6 mm, 8 convex portions,
The die 2 having a spiral lead of 56.7 mm is attached by screws. An outer diameter of 2.08 mm in the inner cavity of the die 2.
A mandrel having a twist pin 3 having a φ, a gap of 6.28 mm and a lead of 56.7 mm is positioned and held by the outer diameter of the spider holder 4. Further, adjacent to the outlet of the die 2, the inner diameter of the projection tip 5a is 14.3 m.
m, the inner diameter of the root 5b of the protrusion is 15 mm, and the rotating mold 5 having eight protrusions is mounted between the die 2 and the die 2 so as to be freely rotatable through a ball bearing. A tray having a V-shaped groove was arranged in front of the rotary mold 5, and the extrusion length was 700 mm.

(Embodiment 1) First, the rotary mold 5 is removed from the above-mentioned apparatus, and the extruder 1 is driven to make the AISI.
A powder having an alloy composition corresponding to T15 was previously mixed and kneaded with a binder to extrude a material to be molded into a plastic kneaded body.
After passing through the spider holder 4, the material to be molded is extruded while being twisted along the inner diameter irregularities of the die. Due to insufficient twist in the die 2, the lead of the spiral hole is 7
It became 9.4 mm-85.6 mm. That is, the lead of the molding material was increased by 40 to 51% with respect to the die and pin lead of 56.7 mm. Also, the hole had an elliptical cross section because it was not twisted along the mandrel. The extrusion speed at this time was 18.9 to 20.6 mm / se.
It was c. It should be noted that, as in the present experiment, the lead obtained by only the extrusion has a high extrusion speed requirement, and the lead also becomes large as the extrusion speed increases.

(Example 2) A push-out test was conducted under the same conditions as in Example 1 except that a rotating mold 5 was attached and this was rotated at a constant drive speed of 20 rpm. The lead of the obtained molded product was 56.8 to 61.8 mm, which was an increase of 0.2 to 9.0% from the lead of the die and the pin, and it was confirmed that the automatic regulation effect of the rotary mold is great. Let However, Example 1
It can be seen that the effect of improving the lead variation (11%) is small in the experiment conducted at. (Embodiment 3) The apparatus used in Embodiment 2 is incorporated with an extrusion length measuring device for a material to be molded, an angle measuring device for measuring a rotation angle of a front surface of the material to be molded, and a control device, but the rotation control is controlled. A system was constructed and in the same manner as in Example 2, the lead target of the molded product was set to 56.7 mm, and automatic control extrusion molding was performed.

The extrusion speed of the material to be molded is 18.9 mm / s.
ec ~ 20.6 mm / sec, but the rotating mold 5
The number of rotations of 20.0 rpm-21.8 rpm was tracked and controlled. Then, the material to be molded is extruded to a predetermined length and cut to have an outer diameter of 14.7 mmφ and an inner diameter of 2.09 mm.
φ, hole spacing 6.24 mm, spiral hole lead 56.5
A high spiral precision sintering material of 56.9 mm (lead error rate 0.7%) was obtained. After the sintering material is dried, it is held in a reducing atmosphere at 400 to 600 ° C. for 2 hours to remove the binder, and the binder-removed body is cooled to 1200 to 1250 ° C.
Vacuum sintering was performed for 2 hours. After sintering, the dimensions of each part were measured. As a result, the outer diameter was 11.9 mmφ and the inner diameter was 1.71 mm.
φ, hole distance 5.08 mm, spiral hole lead 46.0
It was ~ 46.3 mm, and the target dimension could be obtained. The variation ratio of this lead is 0.3 / 46.1.
5 = 0.65%, and the angle error with respect to the axis is 0.65 × 360≈2.3 ° (± 1.15 °).

FIG. 2 is a perspective view of a product obtained by forming a green and sintering it in the same manner as in Example 3. The material 10 has a small hole 10a spirally connected around the axis, and has a spiral groove 10c due to the twist groove of the die and a streak groove due to the protrusion of the rotary die on the outer peripheral surface 10b thereof. 10d is formed. In the example of this figure, the grooves 10c and 10d are designed to have substantially the same depth, and thus the finishing allowance after sintering is minimized. The streak-shaped groove 10d is not parallel to the axis (spiral). This shows that it exerts a rotation regulating effect. In this embodiment and the comparative example, the screw type extruder was used, but the same effect can be obtained by using a piston type extruder, a so-called plunger type extruder.

[0020]

As described above, since the sintered material of the first invention of the present application has small holes with high spiral precision, it is a long material and can be easily chucked by a simple chucking method. It can be processed, and a large cost reduction of twist drills with oil holes can be realized. Further, the second invention of the present application is capable of compensating or suppressing the rotation of the material to be extruded when manufacturing an extruded product with high spiral accuracy, and further constitutes a closed loop which is the third invention of the present application. It is one of the elements to do. The third invention of the present application is
By using the rotation restricting means of the second invention, it is possible to easily manufacture a green having extremely high spiral precision, and thereby it is possible to obtain the sintered product of the first invention of the present application.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of an apparatus for carrying out a method for torsional extrusion molding of a sintering material having spiral holes according to the present invention.

FIG. 2 is a perspective view of a product molded and sintered in substantially the same manner as in Example 3.

[Explanation of Codes] 1 Extruder 1a Cylinder 1b Screw 2 Die 2a Valley of uneven part of die 2b Mountain of uneven part of die 3 Mandrel 4 Spider holder 5 Rotating mold 5a Rotating mold protrusion 5b Rotating mold Root of protrusion 10 Sintered product 10a Spiral small hole 10b Outer peripheral surface 10c Groove 10d Groove

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Iwao Kashiwagi 2107-2 Yasugi-cho, Yasugi-shi, Shimane Prefecture 2 Hitachi Metals Ltd. Yasugi factory

Claims (6)

[Claims] 1. A rod-shaped powder-sintered material having small holes spirally connected to each other around an axis, wherein the small holes within a length of at least 300 mm excluding both ends of the rod-shaped material are constant leads. A sintered material having spiral small holes, wherein an angle error between the spiral and the small holes around the axial center is ± 3.6 ° when it is assumed to follow the spiral. 2. The angle error is within ± 2.5 °.
A sintered material having spiral small holes. 3. A method of extruding a plastic kneading body into a rod shape having small holes spirally connected to each other around an axis, wherein the plastic kneading body has a die having a pin corresponding to the small hole in the opening. 2. A rotation-regulated extrusion molding method comprising: a first step of extruding through a first step; and a second step of constraining the molded material extruded by the above at the outer periphery thereof to restrict the rotation of the molded material. 4. The rotation-regulated extrusion molding method according to claim 3, wherein the constraint on the outer periphery of the material to be molded is made by a plurality of projections that bite the outer peripheral surface of the tip and rotate around the axis. 5. The die has a concavo-convex pattern formed in a spiral shape on the inner peripheral surface thereof, and the projection has a lead in the same direction as the spiral twist with respect to the progress of the material to be molded, and in the same or almost the same lead. The rotation-regulated extrusion molding method according to claim 3 or 4, wherein such a rotation speed is applied. 6. The extrusion molding method of a sintering material having small holes spirally connected around an axis, wherein the extrusion is performed by forming a spiral kneaded concavo-convex pattern on the inner peripheral surface of a plastic kneading material as a raw material. A first step of extruding through a die having a pin corresponding to the small hole in the opening and a rotation regulation for restraining the rotation of the molding material by restraining the molding material extruded by the outer periphery thereof. An extrusion length measuring device for measuring an extrusion length of the material to be molded after the second step, and a rotation for measuring a rotation angle of the material to be molded after the second step. The measurement values of the angle measuring device and the both measuring devices are input, and the control device that controls the rotation angle of the rotation restricting means by comparing these values with a preset value, with respect to the axial center of the small hole. Direction to reduce position error A method for controlling the rotation of a raw material for sintering having spiral small holes, which is characterized in that: