JPH11129300A - Screw device in injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To guarantee highly stable molding action by making the axial center of a screw main body part always surely and precisely coincide with the axial center of a screw head part. SOLUTION: The first centering part 7 which makes the axial center of a screw main body part 5 coincide with the axial center of a screw head part 3 by connecting the screw head part 3 with the screw main body part 5 through a screw connecting part 2 and fitting a centering axial part 8 provided at the front of a screw part 4 on the screw head part 3 into a centering hole part 9 provided at the front of a screw hole part 6 on the screw main body part 5, and the second centering part 10 consisting of the second centering axial part 11 projected backward from the back end part of the screw part 4 and the second centering hole part 12 which fits in the second centering axial part 11 by being provided on the bottom part 6d of the screw hole part 6 and aligns the axial center of the screw main body part 5 with the axial center of the screw head part 3, are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw device for an injection molding machine having a screw head portion screwed to a front end portion of a screw body by a screw connection portion.

[0002]

2. Description of the Related Art Conventionally, a screw device of an injection molding machine having a screw head portion screwed to a front end portion of a screw main body by a screw coupling portion is known from Japanese Patent Publication No. 4-16055.

FIG. 5 shows a conventional screw device 50 of the same configuration. The screw device 50 is loaded inside the heating cylinder 70, and the screw device 50 includes a screw main body 51, a screw head 52 provided at a front end of the screw main body 51, and a screw head 52. The ring valve 53 is provided. The screw head 52 includes a head main body 54 at an intermediate portion, a pointed head tip 55 provided on the front side of the head main body 54, and a predetermined length provided on the rear side of the head main body 54. The small diameter shaft portion 56 and a coupling portion 57 provided rearward from the rear end of the small diameter shaft portion 56 are integrally provided. Further, a plurality of resin flow grooves 58 are formed at predetermined intervals in the circumferential direction on the outer peripheral surface from the head main body portion 54 to the head tip portion 55, and the coupling portion 57 is provided with a front centering shaft portion 59. And the rear threaded portion 60.

On the other hand, at the front end of the screw body 51,
A pressure receiving ring 61 made of a hard material for preventing abrasion when the ring valve 53 comes into contact is attached, and a coupling hole 62 is provided. The coupling hole 62 is formed by a front centering hole 63 and a rear screw hole 64. in this case,
The screw part 60 and the screw hole part 64 constitute a screw coupling part 65, and the centering shaft part 59 and the centering hole part 63 form a centering part 66. The ring valve 53 is formed in a cylindrical shape.

Thus, the ring valve 53 is mounted on the outer peripheral surface of the small-diameter shaft portion 56 of the screw head portion 52, and the coupling portion 57 of the screw head portion 52 is further inserted into the coupling hole portion 61 of the screw body portion 51. When the screw portion 60 is screwed into the screw hole portion 64, the screw head portion 52 is coupled to the screw body portion 51, and the centering shaft portion 59 is fitted into the centering hole portion 63 so that the screw body portion is screwed. The axes of the portion 51 and the screw head portion 52 are aligned. Further, the ring valve 53 has a small diameter shaft portion 56.
A space 67 for resin flow path is provided between the small diameter shaft portion 56 and the ring valve 53 so as to be displaceable in the axial direction on the same axis.

[0006] Therefore, at the time of measurement, the rotation of the screw device 50 causes the resin on the screw body 51 side to move forward, so that the ring valve 53 moves forward to the open position and contacts the head body 54, The resin on the screw body 51 side is measured in front of the screw head 52 through the resin flow space 67 and the resin flow grooves 58. On the other hand, at the time of injection, the screw device 50 moves forward, so that the ring valve 53 moves rearward to the closed position due to the resin measured and accumulated in front of the screw head portion 52 and contacts the front end portion of the screw body portion 51. Then, the resin flow path space 67 is shut off.

In this type of screw device 50 in which the screw head 52 and the screw main body 51 are connected by a screw connecting portion 65, if the screw main body 51 and the screw head 52 do not have the same axis, the screw head 52 is screwed. 52 rotates by eccentricity, and the screw head 52
Not only becomes unstable, but also causes various problems due to the eccentricity such as abrasion between the head main body 54 and the heating cylinder 70. Therefore, the conventional screw device 5
0, the above-described centering portion 66 for aligning the axes of the screw main body portion 51 and the screw head portion 52 is provided.
Since the centering portion 66 is provided at one position in front of the screw connection portion 65, the screw head portion 52 has a particularly high position on the screw head portion 52 due to various factors such as processing accuracy and assembly accuracy of the screw connection portion 65, use conditions, and timekeeping changes. There was a problem that the center of the shaft was eccentric.

The present invention has been made to solve the problems existing in the prior art, and a highly stable molding is achieved by always and accurately aligning the axis of the screw body with the axis of the screw head. An object of the present invention is to provide a screw device of an injection molding machine that can guarantee operation.

[0009]

According to the present invention, a screw portion 4 provided at a rear end of a screw head 3 is screwed into a screw hole 6 provided at a front end of a screw body 5. The screw head portion 3 is connected to the screw main body 5 by a screw connection portion 2. The centering shaft portion 8 provided in front of the screw portion 4 of the screw head portion 3 is connected to the screw hole portion 6 of the screw main body 5. A screw device 1 of an injection molding machine having a centering portion (first centering portion) 7 which fits into a centering hole portion 9 provided at the front and aligns the axis of the screw main body portion 5 with the axis of the screw head portion 3. At the time of construction, the second centering shaft portion 11 protruding rearward from the rear end of the screw portion 4 and the bottom portion 6d of the screw hole portion 6 are fitted to the second centering shaft portion 11 to be screwed. Second centering for aligning the axis of the body 5 and the screw head 3 Characterized in that a second centering section 10 which consists of parts 12.

In this case, according to a preferred embodiment, the second centering shaft portion 11 is formed in a pin shape smaller in diameter than the centering shaft portion 8 provided in front of the screw portion 4, and the second centering hole is formed. Part 12
Can accommodate a regulating block 13 that fills a gap between the bottom 12 d of the second centering hole 12 and the rear end of the second centering shaft 11.

As a result, since the first centering portion 7 is located at the front and rear of the screw coupling portion 2, that is, the second centering portion 10 is located at the front and the second centering portion 10 is located at the rear, the screw body 5 The axis of the screw head 3 and the axis of the screw head 3 are accurately matched without being affected by various factors such as machining accuracy and assembling accuracy of the screw coupling portion 2, use condition and time-measuring change. In addition, if the second centering shaft portion 11 is formed in a pin shape having a smaller diameter than the centering hole portion 9, the accuracy (centering) of centering can be further improved, and the inside of the second centering hole portion 12 can be improved. When the screw 13 is housed in the screw block 4, it is possible to prevent the screw section 4 from being damaged.

[0012]

Next, preferred embodiments according to the present invention will be described in detail with reference to the drawings.

First, the configuration of a screw device 1 according to the present embodiment will be described with reference to FIGS.

In FIG. 1, reference numeral 1 denotes a screw device according to the present embodiment, which is loaded inside a heating cylinder 41.
Comprises a screw body 5, a screw head 3 provided at the front end of the screw body 5, and a ring valve 42 mounted on the screw head 3. The screw device 1 is a screw driving mechanism (not shown). The part is rotated or moved forward and backward. The heating cylinder 41 constitutes a part of an injection device provided in the injection molding machine, and has a hopper for supplying molding material to the inside of the heating cylinder 41 at the rear, and a resin in a mold at a front end. It has an injection nozzle for injection.

The screw head 3 has an intermediate head main body 21, a pointed head tip 22 provided on the front side of the head main body 21, and a predetermined head provided on the rear side of the head main body 21. A small-diameter shaft portion 23 having a length and a coupling portion 24 provided rearward from the rear end of the small-diameter shaft portion 23 are coaxially and integrally formed. Are formed at predetermined intervals in the circumferential direction. Further, the coupling portion 24 includes a front centering shaft portion 8, an intermediate screw portion 4,
A second centering shaft portion 11 projecting rearward from the rear end of the screw portion 4 is integrally formed coaxially. In this case, the second centering shaft portion 11 is formed in a small-diameter pin shape that is about に 対 し て the diameter of the centering shaft portion 8 provided in front of the screw portion 4.

On the other hand, a pressure receiving ring 31 made of a hard material using stellite, boron alloy, cobalt alloy or the like for preventing abrasion when the ring valve 42 comes into contact is attached to the front end of the screw main body 5. Coupling hole 32
Is provided. The coupling hole 32 is a front centering hole 9, an intermediate screw hole 6, and a second centering hole provided at the rear of the screw hole 6, that is, at the bottom 6 d of the screw hole 6. 12 is formed coaxially. When the screw hole 6 and the screw 4 are screwed together, the centering hole 9 and the centering shaft 8 are fitted, and the second centering hole 12 and the second centering shaft 8 are engaged. 11 is fitted.
In this case, the screw portion 4 and the screw hole portion 6 form the screw coupling portion 2, the centering shaft portion 8 and the centering hole portion 9 form the first centering portion 7, and The second centering hole portions 12 constitute the second centering portions 10 respectively. The ring valve 42 is formed in a cylindrical shape.

Next, the function and operation of the screw device 1 according to the present embodiment will be described with reference to FIGS.

First, when assembling the screw device 1,
The ring valve 42 is mounted on the outer peripheral surface of the small diameter shaft portion 23 of the screw head 3, and the connecting portion 24 of the screw head 3 is further connected to the screw main body 5.
The screw portion 4 is screwed into the screw hole portion 6. This state is shown in FIG. As a result, the screw head 3 is coupled to the screw main body 5, and the centering hole 9 and the centering shaft 8, and the second centering hole 12 and the second centering shaft 11, respectively. Fit. On the other hand, the ring valve 42 is mounted coaxially with the small diameter shaft portion 23 so as to be displaceable in the axial direction, and a space 43 for a resin flow path is provided between the small diameter shaft portion 23 and the ring valve 42.

Therefore, two places on both the front and rear sides of the screw connection portion 2,
That is, since the first centering portion 7 is present at the front and the second centering portion 10 is present at the rear, the axes of the screw main body 5 and the screw head 3 are adjusted according to the processing accuracy of the screw coupling portion 2. Without being influenced by various factors such as assembly accuracy, use conditions, and time-measuring changes, it is possible to always consistently and accurately match, and a highly stable molding operation is guaranteed. Also,
Since the second centering shaft portion 11 is formed in a pin shape having a smaller diameter than the centering hole portion 9, the accuracy (centering accuracy) of centering is further improved.

On the other hand, during the molding operation, at the time of weighing,
The rotation of the screw device 1 causes the resin on the screw body 5 side to move forward, so that the ring valve 42 moves forward to the open position and abuts against the rear end face of the head body 21, and The resin on the side is measured in front of the screw head portion 5 through the resin passage space 43 and the resin passage grooves 25. On the other hand, at the time of injection, since the screw device 1 moves forward, the ring valve 42 is moved rearward to the closed position by the resin that is metered and accumulated in front of the screw head portion 3 to move to the front end portion of the screw main body 5 (pressure receiving portion). Abuts the ring 31). As a result, the resin flow path space 43 is shut off.

FIG. 4 shows a modified embodiment. In the modified embodiment, the second core hole 1 is provided inside the second core hole 12.
The second embodiment differs from the embodiment shown in FIG. 1 in that a regulating block 13 that fills a gap between the bottom 12d of the second and the rear end of the second centering shaft 11 is accommodated. The material of the restriction block 13 can be formed of a hard material using the same material as that of the ring valve 42 described above, such as stellite, boron alloy, and cobalt alloy.

In this type of screw device 1, when a force for preventing rotation of the screw head 3 is applied during rotation (at the time of measurement), the screw portion 4 of the screw head 3 is turned into the screw hole 6.
The screw head 3 is forcibly screwed in because the position of the screw head 3 with respect to the screw main body 5 is regulated by housing such a regulating block 13. This can prevent the screw portion 4 from being damaged. Although such a regulating block 13 can be provided between the rear end of the screw portion 4 and the bottom 6d of the screw hole 6, the rear end of the second centering shaft portion 11 and the second centering hole portion can be provided. By accommodating between the bottoms 12d of the twelve, a small diameter regulation block 13 is sufficient, which is advantageous in terms of cost and processing accuracy.

The embodiment has been described in detail above.
The present invention is not limited to such an embodiment,
The configuration, shape, material, quantity, etc. of the details can be arbitrarily changed, added, or deleted without departing from the gist of the present invention.

[0024]

As described above, the screw device of the injection molding machine according to the present invention has a second centering shaft portion projecting rearward from the rear end of the screw portion provided on the screw head portion, and a screw main body portion. A second centering portion consisting of a second centering hole portion that is fitted to the second centering shaft portion by being provided at the bottom portion of the provided screw hole portion to match the axis of the screw main body portion with the axis of the screw head portion. Due to the provision, the following remarkable effects are exhibited.

The axis of the screw body and the axis of the screw head can always be surely and accurately matched,
Thus, a highly stable molding operation can be guaranteed.

According to a preferred embodiment, if the second centering shaft portion is formed in a pin shape having a smaller diameter than the centering shaft portion provided in front of the screw portion, the accuracy (centering) of centering is further improved. be able to.

According to a preferred embodiment, a regulation block that fills a gap between the bottom of the second centering hole and the rear end of the second centering shaft is accommodated inside the second centering hole. For example, it is possible to prevent the screw portion from being damaged by forcibly screwing the screw head portion. In addition, a small-diameter regulating block is sufficient, which is advantageous in terms of cost and processing accuracy.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional side view of a screw device according to an embodiment of the present invention;

FIG. 2 is a sectional view taken along line AA in FIG.

FIG. 3 is a side view of the screw device,

FIG. 4 is a sectional view of a main part of a screw device according to a modified embodiment of the present invention,

FIG. 5 is a partial cross-sectional side view of a screw device according to the related art;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Screw device 2 Screw connection part 3 Screw head part 4 Screw part 5 Screw main body part 6 Screw hole part 6d Bottom part of screw hole part 7 First centering part 8 Centering shaft part 9 Centering hole part 10 Second centering part 11 second centering shaft portion 12 second centering hole portion 12d bottom of second centering hole portion 13 regulating block

Claims (3)

[Claims] 1. A screw connection part for screwing a screw part provided at a rear end part of a screw head part into a screw hole part provided at a front end part of a screw body part and connecting the screw head part to the screw body part. And a centering shaft portion provided in front of the screw portion in the screw head portion is fitted to a centering hole portion provided in front of the screw hole portion in the screw body portion, and the screw body portion In a screw device of an injection molding machine having a centering portion (first centering portion) for aligning the axis of the screw head portion, a second centering shaft portion projecting rearward from a rear end of the screw portion; A second centering portion comprising a second centering hole portion which is fitted to the second centering shaft portion by being provided at the bottom of the screw hole portion and which matches the axes of the screw main body portion and the screw head portion. Injection molding machine characterized by providing Screw device. 2. The screw device for an injection molding machine according to claim 1, wherein said second centering shaft portion is formed in a pin shape having a smaller diameter than a centering shaft portion provided in front of said screw portion. . 3. A regulating block which fills a gap between the bottom of the second centering hole and the rear end of the second centering shaft, inside the second centering hole. The screw device for an injection molding machine according to claim 1, wherein: