JPS5922974Y2 - Ram extrusion molding device for forming cylindrical bodies - Google Patents

Description

[Detailed description of the invention] The present invention relates to a ram extrusion device for forming a cylindrical body, and more specifically relates to a ram extrusion device for forming a cylindrical body.
E) and other polytetrafluoroethylene (PTF)
E) From high-molecular-weight threatening resin powders such as polyimide, aromatic polyamide, etc., which have a low dynamic friction coefficient, high molecular weight, high melt viscosity, and poor fluidity, to particularly thin-walled cylindrical, polygonal, or irregularly shaped cylindrical materials. The present invention provides a ram extrusion device suitable for manufacturing various cylindrical molded products.

A ram extrusion device, which is generally used to extrude a synthetic resin powder having the characteristics listed above into a cylindrical shape, includes an extrusion die equipped with a material supply section and a heating device, and is inserted into the extrusion die and moves reciprocatingly. It consists of a ram and a mandrel that is integrally attached to the tip of the ram, but when molding a cylindrical body with a small wall thickness, it is difficult to form a compressed cake because the contact area with the existing molded body is small. They tend to lack the ability to connect with the body.

Therefore, when the ram is retracted, the compressed cake clings to the mandrel surface and backs up to the material supply section, which has the disadvantage that the raw material powder cannot be continuously supplied.

As a means for suppressing the phenomenon in which the compressed cake clings to the surface of the mandrel when the mandrel retreats, moves away from the pre-formed molded product, and backs up to the rear of the extrusion die, the applicant proposed the following application in 1973.
In No. 7-22644, a synthetic resin extruded body having a shape that is in close contact with the inner wall surface of the extrusion die is interposed at the tip of the ram, that is, the joint between the ram and the mandrel, and a plurality of air vent grooves are carved on the surface of this extruded body. We have proposed a device that can suppress the receding phenomenon of the cake to a certain extent by smoothly discharging the air in the compressed state, but if the compressed cake is particularly thin, it may be difficult to In conjunction with the small contact area, the phenomenon of the compressed cake clinging to the mandle surface becomes more pronounced.

In this invention, when ram extrusion molds thin-walled cylindrical bodies of various shapes in which the ratio S1/S2 of the cross-sectional area S1 of the hollow part of the cylindrical body and the total cross-sectional area S2 of the cylindrical body is 0.06 or more, the ram retracts. In some cases, the compressed cake of the raw material powder clings to the mandrel surface in the caking zone and is prevented from following and retreating to the material supply section, thereby facilitating the continuous supply of the raw material powder and, by extension, continuous molding of the cylindrical body. The present invention provides a ram extrusion device for forming a cylindrical shape.

This idea is based on a ram with a mandrel protruding from the tip of the extrusion die, which has a material supply section installed at the rear of an elongated cylindrical extrusion die, and several heating devices installed in front of the supply section. A cylindrical synthetic resin extruded body with an end face that is in close contact with the inner wall of the extrusion die is interposed at the joint between the ram and the mandrel, and a plurality of air vents are provided on the surface of the extruded body, which extend completely in the direction of ram movement. In addition to the grooves, the mantle has a tapered surface that gradually becomes thinner in the direction toward the tip of the mandrel at the base portion on the ram side, and this tapered surface is used to connect the compressed cake to the pre-formed compact. 1) Continuous forming of ZL and cylindrical bodies by expanding the contact surface and smoothing the exhaust action from the air vent grooves carved on the surface of the extruded body, suppressing the regression phenomenon during molding of compressed cakes. A more specific embodiment of the present invention will be described below with reference to the drawings.

In the figure, 1 is a metallic extrusion die having a circular cross-sectional shape, and three heating devices 4a, 4b, and 4C are sequentially installed from the center part in the axial direction to the front part on the exit side. A material supply section 3 is attached near the rear of the extrusion die.

The respective heating devices 4a, 4b, and 4C have approximately equal lengths and distances corresponding to the sintering process of the molded product, with 4a serving as a caking zone, 4b serving as a melting zone, and 4C as a caking zone. They each form a cooling zone.

A metal ram 7 is inserted into the extrusion die 1 from the rear part of the extrusion die 1.
The ram is inserted leaving an appropriate gap 5 between it and the inner wall surface of the extrusion die, and is reciprocated over a movement width 1 by a hydraulic device 8 connected to the rear end of the ram.

At the tip of this ram 7, a columnar synthetic resin extruded body 9 is screwed and fixed 6, either completely facing the inner wall of the extrusion die 1 or with a slight gap.

Air vent grooves 10 are carved on the circumferential surface of the synthetic resin extruded body 9 in the same direction as the ram axis Jj or in a direction that is inclined, and in particular, the grooves 10 are carved in a concentrated manner on the upper surface of the extruded body 9. The air sealed in the material receiving section 11 is discharged or introduced to provide good air communication between the material receiving section 11 and the outside of the extrusion die 1.

Further, at the tip of the resin extrusion 9, a metal mandrel 12, which can determine the hollow part of the cylindrical molded body, inserts its proximal protrusion 13 into the tip of the ram 7, and The ram 7, the resin extrusion 9, and the mandrel 12 are firmly assembled together with the extrusion 9 interposed in their connecting parts. It is being

This mandrel 12 has a tapered portion 15 that gradually becomes thinner toward the tip in the axial direction at the base portion of the mandrel in contact with the side wall 14 of the resin extruded body 9; The region of the tapered portion 15 extends from the effective end surface 20 of the mandrel in contact with the side wall 14 of the resin extruded body to the region P corresponding to a length within approximately % of the mandrel effective length m from the end surface 20 to the mandrel tip 21. The angle θ of the tapered surface is selected within the range of 3° to 45°, and in this case, the effective length m of the mandrel 12 is approximately Preferably, the length is equal to up to 16.

This is because if the effective length m is larger than the length L of the extrusion die 1, when the cylindrical molded product is extruded from the extrusion die 1, shrinkage may be inhibited by the mandrel and cracks may occur; If it is too large, the shrinkage will be accelerated, making it difficult to manufacture a cylindrical body of a certain size.

In addition, the reason why the area of the tapered portion 15 in the above configuration is set to approximately % of the effective length of the mandrel is that when the ram 7 is advanced, the area within % of the effective length of the mandrel is approximately arranged in the multistages. The melting zone 4b of the heating device 4
This is because even if the tapered portion 15 is provided up to this region, there is no fear that the molded body will be destroyed during melting during heating and compression of the raw material powder.

However, if a portion of the taper is provided beyond this region to the cooling zone 4C, there is a risk that the molded body being cooled will be damaged by strong compressive force.

The raw material powder 17 fed from the material supply section 3 to the material receiving section 11 is compressed by the advance of the ram 7 and becomes a cake 18 in the melting zone 4b into a ready-made cylindrical compact 19.
to be fused and joined.

As a result, the molded body 19 is pushed forward.

Next, the ram 7 retreats to the rear of the material supply section 3 and waits until a predetermined amount of the next raw material powder 17 is introduced into the material receiving section 16.

The above operations are repeated to continuously form a cylindrical body by ram extrusion.

As the material for the mandrel 12 used in this device, hard metals such as mechanical structural carbon steel, nickel chromium steel, nickel chromium monobutylene steel, chrome steel, chrome molybutton steel, etc. are selected for durability. In addition, the surface is slippery, and it is desirable to apply hard chrome plating or nickel plating for rust prevention.

For the resin extruded body 9, a material that satisfies wear resistance, low coefficient of friction, compression resistance, and heat resistance is selected, such as polyimide, polyamideimide, aliphatic polyamide, aromatic polyamide, polyacetal, and phenolic resin. , epoxy resins and various fillers and additives are added to these resins, and glass fibers, carbon fibers, etc. are added to reinforce the extruded body.

As a result, this resin extruded body 9 has a low coefficient of friction with the inner surface of the third extrusion die 1, effectively suppressing the generation of grating sounds and abrasion debris when the ram 7 moves forward and backward. .

Next, we will describe in detail a more specific example using the ram extrusion device according to the present invention, and also list several comparative examples using a device that lacks one component of the present device. do.

Example 1 In an extrusion die with an inner diameter of 80 mm (cross-sectional area: 16π-), an outer diameter of 50 mm (cross-sectional area: 6.25π(1)
), a mandrel with a part of the taper with an inclination angle of θ8° was inserted into the mandrel base portion covering an area up to a point 75 mm from the mandrel base end, and the mandrel was made to have a wall thickness of 15 m.
Figures 1 and 2 are used to form a cylindrical body (pipe) of m.
Ultra-high molecular weight polyethylene powder (trade name Ho5tal
enGVR415 (manufactured by Hoechst) was extruded into a cylindrical shape, and although the cake formed by compression molding in the caking zone hugged the mandrel surface,
When the ram retreated, the raw material powder was continuously supplied without backing up to the material receiving port, and pipes with good appearance and dimensions were continuously formed by ram extrusion.

The surfaces of the mandrel and the mandrel taper portion were plated with hard chrome, and Table 2 shows the materials and dimensions of the parts used in the ram extrusion molding.

Comparative Example 1 A pipe was tried to be formed by ram extrusion of UHMW-PE powder under the same conditions as in Example 1 except that the base of the mandrel lacked a portion of the taper. Occasionally, objects cling to the mandrel surface and retreat to the material receiving section when the ram retreats, causing a situation where the continuous supply of raw material powder is interrupted, and the continuous ram extrusion molding process of pipes is interrupted. There was a problem.

Example 2 In an extrusion die with an inner diameter of 50 mm (cross-sectional area: 6.25 π cm2), a mandrel base portion that has an outer diameter of 20 mm (cross-sectional area: π cm2) and covers an area up to a point of 30 mm in width of the mandrel base end. Insert a mandrel whose taper part with an inclination angle θ18° is cut into the first shape, and the thickness is 15 mm cr).
In order to form a cylindrical body (pipe), a powder of ultra-high molecular weight polyethylene (trade name: Ho5tale) was prepared using the ram extrusion apparatus shown in Figs.
GVR412 (manufactured by Hoechst) was extruded into a cylindrical pipe, and as in Example 1, the compressed cake material did not cling to the mandrel and back up all the way to the material receiving section, and the appearance and texture were good. A continuous ram-extruded pipe was formed.

Table 4 shows the materials and dimensions of the parts used for the above-mentioned ram extrusion molding.

Comparative Example 2 When an attempt was made to form a pipe by ram extrusion molding of UHMW-PE powder under the same conditions as in Example 2 except that a part of the taper was missing at the base of the mantle, a compressed cake was formed in the caking zone. Occasionally, the pipe would cling to the surface of the mandrel and retreat together with the mandrel to the material receiving section, causing problems in pipe work.

The present invention is a ram extrusion device that is effective when ram extruding a cylindrical body.The base part of the mandrel in contact with the extruded resin body is provided with a tapered surface that gradually becomes thinner in the direction toward the tip of the mandrel. Furthermore, due to the extensive surface contact with the inclined end face of the pre-formed compact, the adhesion to the compact becomes stronger, and when the ram retracts, the cake compact and the mandle surface are tightly compressed. By dispersing the adhesion force on the contact surface, the mantle smoothly separates from the cake, preventing the cake from clinging to the mandrel surface when the ram retreats, and furthermore, In particular, the configuration in which air vent grooves are carved in the upper part improves air communication and reduces resistance when the ram advances and retreats, eliminating power loss and making work faster and easier. In addition, the exhaust action of the air vent groove and the above-mentioned elimination of the clinging phenomenon of the cake by the tapered part of the mandrel have a synergistic effect in preventing the cake from receding. This is particularly effective when continuously molding various cylindrical bodies regardless of their thickness.

[Brief explanation of the drawing]

Fig. 1 is a central vertical cross-sectional view of a ram pressing device for vibrator molding according to the present invention, Fig. 2 is an enlarged front view of a partial cutout at the tip of the ram, and Fig. 3 is an A-A in Fig. 2. FIG. 3 is an enlarged cross-sectional view along the line. In the figure, 1 is an extrusion die, 3 is a material supply section, 4 is a heating device,
7 is a ram, 9 is a synthetic resin extrusion body, 10 is an air vent groove,
Reference numeral 12 indicates a mandrel, and reference numeral 15 indicates a portion of the taper.

Claims (3)

[Scope of utility model registration request] (1) A ram with a mandrel protruding from the tip of the extrusion die, which has a material supply section installed at the rear and front of an elongated cylindrical extrusion die, and several heating devices installed in the forward direction from the supply section. A cylindrical synthetic resin extruded body with an end face that is in close contact with the inner wall of the extrusion die is interposed in the joint between the ram and the mandrel, and a plurality of extruded bodies extending in the ram movement direction are inserted on the surface of the extruded body. A ram extrusion molding device for forming a cylindrical body, in which an air vent groove is carved, and a tapered part is formed in the ram side base portion of the mandrel, the taper becoming gradually narrower in the direction of the mandrel tip j5. (2) A ram for forming a cylindrical body according to claim 1, wherein a portion of the taper shaped I=& in the base portion of the mandrel is provided in an area within approximately % of the effective length of the mandrel. Extrusion molding equipment. (3) The air vent grooves are provided concentratedly on one side of the surface of the extruded body.Claim 1 of Utility Model Registration:
A ram extrusion molding device for forming a cylindrical body as described in 2.