JP2000158499A - Method for forming screw head for injection molding machine and injection device for injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming the screw head of an injection molding machine capable of inexpensively and easily forming a projected part having an arbitrary shape at the screw head. SOLUTION: A projected part 3 is formed on the taper surface 2a of a screw head 2 formed in opposed relation to the taper surface 1a formed on the inner surface of the cylinder head 1 of an injection device by build-up welding. The angle of inclination of the taper surface 2a of the screw head 2 is formed (t1<t2) so that the interval with the taper surface 1a of the cylinder head 1 becomes gradually narrow forwardly and the projected part 3 of the taper surface 2a of the screw head 2 is formed so that the interval t3 with the taper surface 1a formed on the inner surface of the cylinder head 1 becomes equal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a projection of a screw head of an injection molding machine and a screw head of the injection molding machine. A method for forming a screw head in which a convex portion is provided on a tapered surface formed to face a tapered surface, and a convex portion is provided on a tapered surface formed to face a tapered surface of a cylinder head. The present invention relates to an injection device of an injection molding machine having a screw head provided.

[0002]

2. Description of the Related Art Conventionally, in order to prevent resin from remaining on the inner wall of a cylinder head or the like of an injection device of an injection molding machine, as disclosed in Japanese Utility Model Publication No. There is known an injection device in which an axial groove is formed in a tapered portion. It is disclosed that the shape of the groove is formed linearly or spirally. In this injection device, when injecting the resin, the tip space formed by the outer surface of the screw head and the inner surface of the cylinder head communicates with the nozzle by a groove formed in the tapered portion of the screw head. And that the remaining resin flows out toward the nozzle due to the pressure difference. Furthermore, it is described that the cross-sectional shape of the groove formed in the tapered portion of the screw head may be an appropriate one such as a semicircle or a square. It is further described that the inclination of the tapered portion of the screw head is equal to that of the inner surface of the cylinder head.

In order to remove resin adhering to an inner wall of a cylinder head or the like of an injection device of an injection molding machine, as disclosed in Japanese Utility Model Laid-Open Publication No. 57-22022, a tapered portion of a screw head has a convex portion. An injection molding machine in which a concave portion is formed is also known. In this injection molding machine, when performing color change or resin change, if the screw head is held at the injection limit and rotated, the resin adhering to the inner wall of the cylinder head by the convex portion will be removed from the convex portion with a slight gap to the cylinder head. It is described that it is peeled off from the cylinder head under a shearing force. It is described that a plurality of convex portions and concave portions are alternately formed in a tapered portion, or that the cross section of the tip end of the screw head has an omsby shape to form the convex portions and the concave portions.

[0004]

Problems to be Solved by the Invention
As disclosed in Japanese Patent No. 98425, when a groove is formed in a tapered portion of a screw head, a cutting tool is prepared according to the cross-sectional shape of the groove to be formed. And it must be attached to the cutting device, and there is a problem that cost and labor are required.

Further, when the convex and concave portions of the tapered portion of the screw head disclosed in Japanese Utility Model Laid-Open No. 57-22022 are formed by cutting a material or the like, the processing shape is large. There is a problem that a lot of waste occurs in the material, and it takes time and effort for cutting. Further, in this case, since it is difficult to form a convex portion and a concave portion on a screw head having a tapered surface having a slope as conventionally used, the convex portion and the concave portion are difficult. However, there is a problem in that a screw head having the above-mentioned structure must be newly formed, which increases costs.

Further, when the gap between the tapered surface of the screw head and the tapered surface formed on the inner surface of the cylinder head is formed so as to change for a while toward the front, the above-mentioned groove or convexity is required. There is a problem that control of a tool in an apparatus for cutting a part and a concave part into an arbitrary shape is complicated and difficult.

[0007] Then, any of the above-mentioned prior arts,
The gradient between the tapered portion of the screw head and the tapered surface of the cylinder head is almost equal, and the pressure of the resin at such a portion does not increase more than the pressure up to the screw head. For this reason, since the flow speed of the resin in such a portion does not increase more than the flow speed due to the compression of the screw, the resin easily stays, and it is not possible to purge the resin deposited when performing resin change or color change. Further, the resin staying in the cylinder head is carbonized by overheating. In order to remove the resin before resin change or color change, or to remove carbonized resin, the operation must be stopped and the inside of the cylinder must be cleaned, which raises the problem of increasing the cost of resin molding. Was.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a method for forming a screw head of an injection molding machine, which can easily and inexpensively form a convex portion having an arbitrary shape on a screw head. With the goal. Another object of the present invention is to provide a method for forming a screw head of an injection molding machine, which can easily form the screw head of the injection molding machine in a shape in which resin does not accumulate. Still another object of the present invention is to provide a screw head of an injection molding machine that has a simple structure and does not deposit resin, and can reliably perform resin change and color change.

[0009]

According to a first aspect of the present invention, there is provided a method for forming a screw head of an injection molding machine, wherein the screw head is formed on an inner surface of a tip end of a cylinder head of an injection device of the injection molding machine. A method for forming a screw head in which a convex portion is provided on a tapered surface formed to face a tapered surface, wherein the convex portion is formed by overlay welding on the tapered surface of the screw head. It is a feature.

The invention according to a second aspect of the present invention relates to a method for forming a screw head of an injection molding machine.
According to the first aspect of the present invention, the gap between the tapered surface of the screw head and the tapered surface of the cylinder head is formed so as to be gradually narrowed toward the front, and thereafter, the inclination with the tapered surface of the cylinder head is reduced. It is characterized in that a convex portion is formed by overlay welding on the tapered surface of the screw head so as to be substantially equal.

According to a third aspect of the present invention, in order to achieve the above object, a projection is provided on the tapered surface so as to face the tapered surface formed on the inner surface of the cylinder head. An injection device of an injection molding machine having a screw head, wherein the inclination angle of the tapered surface of the screw head is formed such that the interval between the tapered surface of the cylinder head and the tapered surface of the cylinder head becomes narrower for a while, and the screw is formed. The convex portion of the tapered surface of the head is formed so that the interval between the tapered surface and the tapered surface of the cylinder head is uniform.

According to the first aspect of the present invention, by overlay welding on the tapered surface of the screw head, the resin can be formed into an arbitrary shape having an optimum shape so that resin does not stay between the tapered surface of the screw head and the tapered surface of the cylinder head. Form a convex part.

According to a second aspect of the present invention, in the first aspect of the present invention, the gap between the tapered surface of the screw head and the tapered surface of the cylinder head is formed so as to be gradually narrowed toward the front. When the resin is injected, the screw head of the injection device can be easily formed into a shape that can surely increase the flow velocity of the resin in such a portion and also can prevent the resin from being deposited by scraping the resin.

According to the third aspect of the present invention, the inclination angle of the surface of the screw head having the tapered surface is formed so that the distance between the tapered surface of the screw head and the tapered surface of the cylinder head becomes narrower as it goes forward. When the resin is injected, the flow velocity of the resin in such a portion is increased and does not stay, so that the accumulation of the resin is prevented. In addition, by forming the convex portion on the surface of the screw head so that the distance between the screw head and the tapered surface of the cylinder head becomes uniform, the screw can be rotated around the axis at the limit of forward movement every time the resin or color is changed. As a result, the resin in the cylinder head is scraped off, so that the resin used up to that time does not remain in the cylinder head, and the resin is reliably switched to the newly used resin.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described in detail with reference to FIGS. The same reference numerals in the drawings denote the same or corresponding parts.

The injection device according to the present invention generally includes an injection head including a screw head 2 having a projection 3 provided on a tapered surface 2a formed opposite to a tapered surface 1a formed on the inner surface of a cylinder head 1. In the injection device of the molding machine, the inclination angle of the tapered surface 2a of the screw head 2 is formed so that the interval between the tapered surface 2a formed on the inner surface of the cylinder head 1 becomes narrower as it goes forward. (T1 <t2), the tapered surface 2a of the screw head 2
Are formed so that the interval t3 between the convex portion 3 and the tapered surface 1a formed on the inner surface of the cylinder head 1 becomes uniform.

The method of molding a screw head of an injection molding machine according to the present invention generally comprises forming a convex portion on a tapered surface 2a formed on an inner surface of a cylinder head 1 of an injection device. 3. A method for forming a screw head provided with 3, comprising:
The convex portion 3 is formed by overlay welding on the tapered surface 2a.

Further, according to the method of molding a screw head of an injection molding machine of the present invention, a tapered surface 2a of a screw head 2 is provided.
(T1) is formed such that the distance between the cylinder head 1 and the tapered surface 1a of the cylinder head 1 becomes narrower as it goes forward.
<T2) Then, the convex portion 3 is formed by overlay welding on the tapered surface 2a of the screw head 2 so that the inclination with the tapered surface 1a of the cylinder head 1 becomes substantially equal.

A screw 12 is inserted into the cylinder 11 for plasticizing and kneading the injected resin.
As is well known, the screw 12 is formed with a spiral groove 12a on its peripheral surface, and is driven to rotate around an axis and is moved in the axial direction. A screw head 2 having a tapered surface 2a is attached to a tip of the screw 12, and a check ring 15 is provided at a small diameter portion between the tip of the screw 12 and the screw head 2.

A base of a nozzle 16 for introducing the melt-plasticized and injected resin into a mold (not shown) is screwed to the tip of the cylinder 11. Nozzle 16
The base portion has a tapered surface 1a formed therein, and constitutes the cylinder head 1.

The inclination angle of the tapered surface 2a of the screw head 2 is determined by the tapered surface 1a formed on the inner surface of the cylinder head 1.
The angle is set so that the angle is closer to the axis C than the inclination angle of a. Therefore, the tapered surface 2a of the screw head 2 and the tapered surface 1a of the cylinder head 1
As shown in FIG. 1, the distance t1 is formed such that the distance t1 at the front is narrower than the distance t2 at the rear, that is, the distance t1 becomes narrower from the rear toward the front.

On the tapered surface 2a of the screw head 2 formed as described above, a convex portion 3 having a predetermined direction, cross-sectional shape, thickness, or number is formed by overlay welding by arc welding, gas welding, or the like. . And the direction of the convex part 3,
When the cross-sectional shape, thickness, or number exceeds a predetermined amount, the convex portion 3 formed by overlay welding is subjected to removal processing, such as cutting or grinding, so as to be adjusted to a predetermined shape. The cross-sectional shape of the convex portion 3 in the axial direction is, as shown in FIG. 2, a shape having a substantially semicircular shape, and as shown in FIG. 4, or a shape having a substantially trapezoidal shape as shown in FIG. The convex portion 3 is formed so that the interval t3 between the distal end edge 3a outside the axis C and the tapered surface 1a of the cylinder head 1 is equal between the front and the rear, that is, the convex with respect to the axis C. The inclination of the portion 3 and the inclination of the tapered surface 1a of the cylinder head 1 are substantially equal. In the embodiment shown in the drawings, the protrusion 3 is formed such that one protrusion extends substantially the entire length in the axial direction of the tapered surface 2 a of the screw head 2. The present invention is not limited to this embodiment.
Can be appropriately formed in an optimum shape for scraping off the resin between the tapered surface 1a of the cylinder head 1 and the like by, for example, spirally dividing the resin in the axial direction.

Next, the operation of the injection device having the screw head 2 formed as described above will be described. In a normal state, the screw 12 is driven to rotate around the axis in the cylinder 11, and the resin charged in the cylinder 11 is melt-plasticized in a compression section located in front of the supply section, and is kneaded and kneaded. , And is reliably stored at the tip of the cylinder 11 by the action of the check ring 15. Then, as the amount of resin melt-plasticized and stored at the tip in the cylinder 11 increases, the screw 12
Is moved backward to a predetermined position and weighing is performed. Thereafter, when the screw 12 is driven forward by an axial driving device (not shown) such as a hydraulic cylinder in a state where the nozzle 16 is in contact with a mold (not shown), the screw 12 is plasticized and melted and weighed. A fixed amount of resin will be injected into the mold. The forward position of the screw 12 at this time is slightly behind the forward limit position set so that the convex portion 3 provided on the screw head 2 does not collide with the tapered surface 1a of the cylinder head 1. The flow of the resin between the tapered surface 2a of the screw head 2 including the convex portion 3 and the tapered surface 1a of the cylinder head 1 is ensured.

Since the interval between the tapered surface 2a of the screw head 2 and the tapered surface 1a of the cylinder head 1 is formed so as to become narrower from the rear to the front (t1 <t2), the resin is discharged from the nozzle 16. When the resin is injected into the mold, the pressure of the resin passing through the two tapered surfaces 1a and 2a is increased, and the flow speed is increased so that the resin does not stay. Remains and is not heated and carbonized.

On the other hand, when performing resin change or color change,
The screw 12 is rotationally driven around an axis while being driven forward to the forward limit. Tapered surface 2a of screw head 2
Is formed so that the distance between the tip end of the convex portion 3 and the tapered surface 1a of the cylinder head 1 is uniform. Since the resin that has been removed is not scraped off and remains in the cylinder head 1, and therefore can be reliably switched to a newly used resin, the color change without stopping the operation of the injection molding machine and cleaning. And resin change can be easily performed.

[0026]

According to the first aspect of the present invention, a convex portion is formed on the tapered surface of the screw head by overlay welding to easily form a convex portion of any shape on the screw head at low cost. And a method for forming a screw head of an injection molding machine.

According to the second aspect of the present invention, the gap between the tapered surface of the screw head and the tapered surface formed on the inner surface of the cylinder head is formed so as to be gradually narrowed toward the front, and thereafter the cylinder is formed. By forming a convex portion by overlay welding on the tapered surface of the screw head so that the inclination with the inner surface of the head is almost equal, the screw head of the injection molding machine can be easily formed in a shape in which resin does not accumulate. And a method for forming a screw head of an injection molding machine.

According to the third aspect of the present invention, the inclination angle of the tapered surface of the screw head is formed so that the interval between the tapered surface and the tapered surface formed on the inner surface of the cylinder head becomes narrower as it goes forward. By forming the convex portion of the tapered surface of the screw head so that the interval between the tapered surface formed on the inner surface of the cylinder head is uniform, no resin is deposited with a simple structure, Also,
It is possible to provide a screw head of an injection molding machine capable of reliably performing resin change and color change.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a main part of an injection device of an injection molding machine of the present invention.

FIG. 2 is a plan view of a projection formed on a screw head,
It is a partial view showing one embodiment of a section shape in A line.

FIG. 3 is a plan view of the projection formed on the screw head,
FIG. 4 is a partial view showing another embodiment of the cross-sectional shape taken along line A, which is different from FIG. 2.

FIG. 4 is a plan view of a projection formed on the screw head,
FIG. 4 is a partial view showing another embodiment of the cross-sectional shape taken along line A, which is different from FIGS. 2 and 3.

[Description of sign]

DESCRIPTION OF SYMBOLS 1 Cylinder head 1a Tapered surface 2 Screw head 2a Tapered surface 3 Convex part t1 Distance between tapered surface of cylinder head and tapered surface of screw head t2 Distance between tapered surface of cylinder head and tapered surface of screw head t3 Cylinder head Between the tapered surface of the screw and the tip of the protrusion provided on the tapered surface of the screw head

Claims (3)

[Claims] 1. A method for forming a screw head in which a convex portion is provided on a tapered surface formed to face a tapered surface formed on an inner surface of a cylinder head of an injection device of an injection molding machine, A method for forming a screw head of an injection molding machine, wherein a convex portion is formed by overlay welding on a tapered surface of the screw head. 2. The gap between the tapered surface of the screw head and the tapered surface of the cylinder head is formed so as to gradually become narrower toward the front, and thereafter, the inclination with the tapered surface of the cylinder head becomes substantially equal. 2. The method according to claim 1, wherein the protrusion is formed by overlay welding on the tapered surface of the screw head. 3. An injection device for an injection molding machine comprising a screw head having a convex portion provided on a tapered surface formed opposite to a tapered surface formed on an inner surface of a cylinder head, wherein the taper of the screw head is provided. The inclination angle of the surface is formed so that the interval between the tapered surface of the cylinder head and the tapered surface of the cylinder head become narrower for a while, and the convex portion of the tapered surface of the screw head is formed between the tapered surface of the cylinder head and the convex portion. A screw head for an injection molding machine, wherein the screw head is formed so as to have a uniform interval.