JPH037320A - Extrusion molding apparatus - Google Patents

Abstract

PURPOSE:To easily extrude even under a low pressure by forming a heat generated part of a mandrel in a conical shape having an end becoming a large diameter, and enlarging in diameter toward its end so that the bore of a position corresponding to the heat generated part of a heat generating cylinder becomes parallel to the outer wall of the corresponding heat generated part at a predetermined gap. CONSTITUTION:Rubber or elastomer extruded from an extruder 10 into a heat generating cylinder 12 is advanced between the inner wall of the cylinder 12 and the outer wall of a heat generating part 14a of a mandrel 14 by pressure from the extruder 10 side. Since the mandrel 14 is rotated at its axis as a center, a material is effected by a frictional force from the inner wall and the outer wall to generate heat by its shearing operation. Since the shape of the part 14a is formed to be conical at the end being thick, the end of the part 14a is accelerated to be faster than the base side, stronger shearing force is operated at the material to generate heat to be softened. When the ratio of diameters of the base of the part 14a to the end thereof is set to 1:1.3-1.5, the same effect in which the rotating speed of the mandrel is increased by 30-50% at the end with respect to the base is obtained, much material is heat- generated to increase its fluidity.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an extrusion molding apparatus.

(Prior art) In an extrusion molding device for rubber or elastomer, rubber or elastomer is continuously vulcanized by shear heat generation, or heated to near the crosslinking temperature, and then extruded to the molding section (Japanese Patent Publication No. 1983-1999). 58895).

In the apparatus disclosed in the above publication, a rubber or elastomer extrusion tube containing an extrusion screw and the material coming out from the end of the extrusion tube are received through a connecting tube, guided between a relatively rotating mandrel and an inner wall, where they are sheared and heated, and the material is heated by shearing in the molding section. The gap between the heat generating cylindrical surface of the mandrel and the inner wall of the heat generating cylinder is 5 to 25 III! 1, the axial length of the heat generating gap is set to 1 to 2.5 times the inner wall diameter of the heat generating cylinder.

(Problems to be Solved by the Invention) In the conventional extrusion molding machine described above, the mandrel is formed into a cylinder, the heating cylinder is formed into a cylinder, and the outer wall of the mandrel and the inner wall of the heating cylinder are set parallel, and the gap between them is Since it is set to a large value of 5 to 25 m+, it has the advantage of making it possible to extrude a material with high viscoelasticity such as rubber.

However, making the outer wall of the mandrel and the inner wall of the heating cylinder parallel to each other and increasing the gap between them means that the shearing effect on the material is reduced, and depending on the material, the rotation speed of the mandrel may be increased. However, sufficient heat generation may not be obtained even when using rubber, especially when using vulcanizing agents,
Depending on the blending conditions of the vulcanization accelerator and the like, there is a problem in that sufficient heat generation may not be achieved to near the vulcanization temperature.

Furthermore, there is a risk that the material may not soften sufficiently due to heat generation, and there is a problem that extrusion is impossible at low pressure.

Therefore, the present invention was made to solve the above problems, and its purpose is to provide extrusion molding that allows the required heat generation of the material even at a low rotation speed of the mandrel, and that allows extrusion even at low pressure. We are in the process of providing equipment.

(Means for Solving the Problems) In order to achieve the above object, in the extrusion molding apparatus according to the present invention, a rubber or elastomer material fed from an extruder is applied to the inner wall of the heat generating cylinder and an axis line inside the heat generating cylinder. In an extrusion molding device that performs vulcanization by shearing between the outer wall of a heat generating part of a mandrel that is rotatably built in as a center, or by raising the temperature to near the crosslinking temperature and extruding it from a goo in a molding part, the heat generated by the mandrel is The section is formed in a truncated conical shape with a larger diameter toward the distal end, and extends toward the distal end so that the inner diameter of the section corresponding to the heat generating section of the heat generating cylinder is parallel to the corresponding outer wall of the heat generating section with a predetermined gap. It is characterized by an enlarged diameter.

(Function) In the present invention, the heat generating portion of the mandrel is formed into a truncated conical shape with a tapered part, and the corresponding heat generating cylinder is formed into a cylindrical shape parallel to the outer wall of the heat generating portion and whose diameter increases toward the tip. Since the space between the parts is formed to be constant, materials with high viscoelasticity such as rubber can be extruded as before, and the peripheral speed is higher on the tip side of the heat generating part than on the base side. Because there is
The closer you go to the tip of the heat generating part, that is, the closer you get to the forming part, the greater the shearing action becomes, and even if the mandrel rotation speed is low, the necessary heat generation in the forming part can be easily obtained, and the closer you go to the tip, the stronger the shearing action becomes. Since the degree of softening is greater than before, extrusion can be easily performed even at low pressure.

The volume of the space between the heat generating part of the mandrel and the heat generating tube increases as it goes towards the tip of the heat generating part of the mandrel. Since the temperature is lower and therefore the residence time is longer, a higher exotherm is obtained.

(Embodiments) Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

In the figure, an extruder 10 has an extrusion screw (not shown) built therein, and extrudes rubber or elastomer into a heat generating cylinder 12.

A mandrel 14 is built into the heating cylinder I2, and this mandrel 14 is rotated about an axis by a motor (not shown) via a reduction gear.

A discharge screw 16 is formed in the middle of the mandrel 14 so as to be in sliding contact with the inner wall of the heat generating cylinder 12. 18 is a discharge hole formed in the heat generating cylinder 12.

The part of the mandrel ahead of the part slidingly in contact with the inner wall of the heat generating cylinder, including the discharge screw 16 part, is formed in the heat generating part 14 a with a predetermined gap formed between it and the inner wall of the heat generating cylinder 12 . The tip is shaped like a cone.

The material extruded from the extruder 10 is guided through the channel 2° into the gap on the base side of the heat generating part 14a.

A feature of the present invention is that the heat generating portion 14a of the mandrel 14 is formed into a truncated cone shape whose diameter increases mysteriously toward the tip.

Further, the inner diameter of the heat generating cylinder 12 corresponding to the heat generating part 14a is also expanded toward the distal end in parallel with the outer wall of the heat generating part in accordance with the shape of the heat generating part 14a.
A gap of constant thickness is formed between the outer wall and the outer wall.

The ratio of the diameter of the base side of the heat generating part 14a to the diameter of the thickest part at the tip is approximately 1:1, although it depends on the length of the heat generating part 14a.
It is preferable to set it to about 3 to 1.5.

The flow path ahead of the heat generating part 14a is narrowed approximately along the shape of the tip of the mandrel 14, and then connected to the forming part 22. A die 24 is attached to the tip of the molding part 22.

Note that a band heater 26 or the like is appropriately attached to the outside and top of the molding section 22 so as to adjust the temperature.

28.30 is a pressure gauge.

Although not shown, a thermometer is provided to detect the temperature of the material inside the molding section 22 and the like.

Since the configuration is as described above, the rubber and elastomer extruded from the extruder ``0'' into the heat generating cylinder 12 are
It moves between the inner wall of the heat generating cylinder 12 and the outer wall of the heat generating part 14a due to the pressure from the zero side. Here, since the mandrel 14 is rotating around its axis, the material is
Frictional force acts from the inner wall and the outer wall of the heat generating portion 14a, and heat is generated due to shearing action.

In the present invention, the shape of the heat generating part 14a of the mandrel 14 is a truncated cone shape with a thick taper as described above, so the circumferential speed is higher on the tip side of the heat generating part 14a than on the base side, and the material is more A strong shearing force acts on it, generating heat and softening it.

The diameter ratio of the base side and the tip side of the heat generating part 14a is 1:1.3.
If it is 1.5, the same effect as increasing the number of rotations of the mandrel by 30% to 50% can be obtained on the tip side compared to the base side, and the material can generate more heat.

In the case of rubber, the higher the temperature, the easier the rubber will flow around the vulcanization temperature, which is called the softening point in boat fishing. Therefore, by tapering the shape of the heat generating portion 14a as described above, the rubber on the tip side becomes softer than on the base side, thereby increasing fluidity. Fluid flows in the direction of faster flow, and this also makes it easier for the material to flow toward the tip of the heat-generating portion 14, where the circumferential velocity is high (and even if the pressing force from the base side is low). be.

Note that the volume of the gap between the inner wall of the heat generating cylinder 12 and the outer wall of the heat generating portion L4a is larger on the tip side of the heat generating portion 14a than on the base side, so in that sense, the flow of material is slower on the tip side. As mentioned above, since the fluidity is high, it flows easily even with a low pressing force. Furthermore, the slower the flow is on the tip side, the longer the residence time in the area where a greater shearing force can be obtained, and the -layer heat generation effect is enhanced.

Therefore, this also means that the length of the heat generating portion 14a can be shortened, and the device can be made smaller.

The material fluidized as described above flows into the forming section 22, is extruded from the die 24, and is molded.

Although it is unlikely that material will enter between the sliding contact part of the mandrel 14 and the inner wall of the heat generating cylinder 12, even if it does, it will be sent into the discharge hole 18 by the discharge screw 16 and discharged, so that the rubber This prevents clogging due to burns such as burns.

The present invention has been variously explained above with reference to preferred embodiments, but the present invention is not limited to these embodiments, and it goes without saying that many modifications can be made without departing from the spirit of the invention. That's true.

(Effects of the Invention) In the present invention, the heat generating portion of the mandrel is formed in the shape of a truncated cone with a thicker end, and the corresponding heat generating tube is formed in the shape of a cylinder parallel to the outer wall of the heat generating portion and expanding in diameter toward the front. Since the space between the two is constant, materials with high viscoelasticity such as rubber can be extruded as before, and the peripheral speed is higher on the tip side of the heat generating part than on the base side. Because it is large,
The closer you go to the tip of the heat generating part, that is, the closer you get to the forming part, the greater the shearing action becomes, and even if the mandrel rotation speed is low, the necessary heat generation in the forming part can be easily obtained, and the closer you go to the tip, the stronger the shearing action becomes. Since the degree of softening is greater than before, extrusion can be easily performed even at low pressure.

The volume of the space between the mandrel's heat generating part and the heat generating tube increases as it goes towards the tip of the mandrel's heat generating part, so the residence time of the material is longer at the part of the mandrel's heat generating part where a greater shearing action can be obtained. Therefore, more heat can be generated.

[Brief explanation of drawings]

The drawing is a partially cutaway sectional view showing a preferred embodiment of the extrusion molding apparatus according to the present invention. 10... Extruder, 12... Heat generating cylinder, 4 20... Mandrel, - Channel, 4... Gui.・Heating part,

Claims (1)

[Claims] 1. Rubber or elastomer material sent from an extruder is placed between the inner wall of the heat generating cylinder and the outer wall of the heat generating part of a mandrel that is rotatably built in the heat generating cylinder around an axis. In an extrusion molding device that performs vulcanization by shearing at a temperature, or extrudes through a die of a molding section after raising the temperature to near the crosslinking temperature, the heat generating section of the mandrel is formed in a truncated conical shape with a larger diameter toward the tip, An extrusion molding device characterized in that the inner diameter of a portion of the heat generating tube corresponding to the heat generating portion increases toward the distal end so that the inner diameter of the portion corresponding to the heat generating portion corresponds to the outer wall of the corresponding heat generating portion with a predetermined gap therebetween.