JPH11129298A - Screw head device in injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively and sufficiently prevent a resin from being retained and to surely avoid lowering quality of molding and failure of molding caused by deterioration of the retained resin. SOLUTION: A screw head device 1 comprises a screw head part 5 having a peaked head apex part 3 at the front side of a head main body part 2 and a small diameter shaft part 4 connected with the front end of a screw main body Sm on the back side, and a ring valve 6 freely movably mounted in the axial direction coaxially with the small diameter shaft part 4, a plurality of channels 7 for resin flow paths provided at a specified interval in the peripheral direction on the outer peripheral face from the head main body part 2 to the head apex part 3, and a space 8 for a resin flow path is provided between the small diameter shaft part 4 and the ring valve 6. Protruded parts 9 protruded in a circular arc-like shape to the outside in the diameter direction from the outer peripheral face 4s of the small diameter shaft part 4 are respectively provided on the bottom faces 7d of the channels 7 for the resin flow paths.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw head device for an injection molding machine having a screw head provided with a ring valve.

[0002]

2. Description of the Related Art FIG. 6 shows a general screw head device 50 provided in an injection molding machine. In the figure, reference numeral 60 denotes a screw loaded inside a heating cylinder 61. The screw 60 includes a screw main body 62 and a screw head device 50 provided at a front end of the screw main body 62. The screw head device 50 includes a screw head portion 51 and a ring valve 52, and further includes a screw head portion 51.
The head main body 53 at the intermediate portion and the head main body 5
3 and a small-diameter shaft portion 55 having a predetermined length and connected to the front end of the screw body 62 by being provided behind the head body portion 53. Head 53 to head tip 5
On the outer peripheral surface reaching No. 4, a plurality of resin flow channel grooves 56 are provided at predetermined intervals in the circumferential direction. In this case, the bottom surfaces of the resin flow channels 56 coincide with the extension of the outer peripheral surface of the small diameter shaft portion 55. On the other hand, the ring valve 52 is formed in a cylindrical shape, and is mounted coaxially with the small diameter shaft portion 55 so as to be displaceable in the axial direction. Thus, a resin flow path space 57 is provided between the small diameter shaft portion 55 and the ring valve 52.

[0003] Therefore, at the time of weighing, the rotation of the screw 60 causes the resin on the screw body 62 side to move forward, so that the ring valve 52 moves forward to the open position and abuts on the head body 53, and the screw body 52 62
The resin on the side is a resin flow path space 57 and a resin flow path groove 56.
Weighed in front of the screw head 51 through the On the other hand, since the screw 60 moves forward at the time of injection, the ring valve 52 moves rearward to the closed position due to the resin measured and accumulated in front of the screw head portion 51 and abuts on the front end of the screw main body 62, and the resin flow is reduced. The road space 57 is shut off.

[0004] In the screw head device 50, the geometrical shape of each part including the shape of the screw head portion 51, the resin flow path and the flow rate, and the rotation of the screw 60 cause the resin at the time of weighing. 6 does not smoothly pass through the resin flow grooves 56, and there is a problem that a part of the resin stays at the position indicated by the symbol Xs in FIG.

On the other hand, in order to solve this problem, a conventional injection molding screw in which the groove for the resin flow path is inclined with respect to the axial direction of the screw head portion to thereby prevent the resin from stagnating is also known. Although disclosed in Japanese Unexamined Patent Publication No. 9-70863, such a conventional screw can eliminate the cause of stagnation due to the rotation of the screw to some extent.
Other causes, for example, because the tip of the head is pointed, when the resin passes through the groove for the resin flow path, the resin flows out into the heating cylinder earlier on the outer peripheral side, and stays more easily on the center side. Is not resolved. As a result, there is a problem that the retention of the resin cannot be effectively and sufficiently prevented, and that the degradation of the molding resin due to the deterioration of the retained resin and the molding failure cannot be reliably eliminated.

The present invention has been made to solve the problems existing in the prior art, and can effectively and sufficiently prevent the stagnation of the resin, and can surely eliminate the deterioration of the molding quality and the molding failure due to the deterioration of the stagnation resin. An object of the present invention is to provide a screw head device of an injection molding machine.

[0007]

SUMMARY OF THE INVENTION The present invention is directed to a head body 2 having a pointed head end 3 at the front side of a head body 2 and a predetermined length connected to the front end of a screw body Sm at the rear side. A screw head portion 5 having a small diameter shaft portion 4 and a ring valve 6 that is mounted coaxially with the small diameter shaft portion 4 so as to be displaceable in the axial direction are provided on an outer peripheral surface from the head main body portion 2 to the head tip portion 3. A plurality of resin flow grooves 7 are provided at predetermined intervals in the circumferential direction, and a screw head device 1 of an injection molding machine is provided in which a resin flow space 8 is provided between the small-diameter shaft portion 4 and the ring valve 6. In this case, in particular, a raised portion 9 that rises in an arc shape radially outward from the outer peripheral surface 4s of the small-diameter shaft portion 4 is provided on the bottom surface 7d of the resin flow channel groove 7.

In this case, according to a preferred embodiment, the raised portions 9 have a front portion 9f formed continuously on the outer peripheral surface 3s of the head distal end portion 3 and a rear portion 9r formed with the resin flow channel grooves 7.
Of the small-diameter shaft portion 4. The resin flow channel grooves 7 can be provided in the direction of the axis Fc of the screw head 5, and have a predetermined angle Q, preferably 12 to 1 with respect to the direction of the axis Fc.
It may be provided in the direction Fa inclined at an angle of 5 °.

As a result, the space in which the resin stays in the resin flow channel grooves 7 is filled with the raised portions 9, so that the space in which the resin stays is eliminated, and as a result, the resin is prevented from staying. . Further, since the effective cross-sectional area through which the resin passes in the intermediate portion of the resin flow channel groove 7 becomes relatively smaller than before and after due to the raised portions 9, the resin flow channel groove 7 is formed.
The flow velocity of the resin in the middle part of ... is increased, and as a result,
Stagnation is less likely to occur.

[0010]

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

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

In the drawing, reference numeral 30 denotes a screw loaded inside a heating cylinder 31, and this screw 30 is a screw main body Sm.
And the screw head device 1 according to the present embodiment provided at the front end of the screw body Sm. The heating cylinder 31 constitutes a part of the injection device provided in the injection molding machine. The heating cylinder 31 is provided with a hopper for supplying molding material into the heating cylinder 31 at the rear, and a resin is injected into a mold at the front end. It has an injection nozzle. Further, the screw 30 is rotated or moved forward and backward by a screw driving mechanism unit connected to the rear end.

On the other hand, the screw head device 1 includes a screw head portion 5 and a ring valve 6. The screw head 5 includes an intermediate head main body 2 and the head main body 2.
And a small-diameter shaft portion 4 having a predetermined length, which is provided on the rear side of the head main body 2 and is connected to the front end of the screw main body Sm. The outer peripheral surface from the main body 2 to the head tip 3 has a plurality of resin flow channel grooves 7 at predetermined intervals in the circumferential direction. In this case, the resin flow grooves 7 are provided in the direction of the axis Fc of the screw head 5 as shown in FIG.

Further, the ring valve 6 is formed in a cylindrical shape, and a tapered surface whose outer peripheral surface is located forward is provided on the front end surface. For this reason, the rear end surface of the head main body 2 is formed as an inclined surface that comes into surface contact with the tapered surface. The ring valve 6 is mounted coaxially with the small diameter shaft portion 4 so as to be displaceable in the axial direction. Thereby, the ring valve 6
A space 8 for a resin flow path is provided between the ring valve 6 and the small-diameter shaft portion 4, and when the ring valve 6 is displaced forward,
The front end contacts the rear end of the head main body 2 to open the resin flow path space 8, and when the ring valve 6 is displaced rearward, the rear end contacts the front end of the screw main body Sm to allow the resin flow. The road space 8 is shut off.

The rear end face of the head main body 2 against which the ring valve 6 contacts and the front end face of the screw main body Sm are:
There is a risk that the ring valve 6 will wear down due to contact. Therefore, the rear end face of the head main body 2 is hardened by welding a hard material 11 using stellite, boron alloy, cobalt alloy, or the like, and the front end face of the screw main body Sm has the same shape as the hard material 11. A donut-shaped seat ring 12 formed of the above material is attached.

On the other hand, according to the present invention, on the bottom surfaces 7d of the grooves 7 for resin flow passages, there are provided raised portions 9 which are raised radially outward in an arc shape with respect to the outer peripheral surface 4s of the small diameter shaft portion 4.
Thereby, the raised portions 9 are provided in a circular arc shape outward in the radial direction with respect to the conventional bottom surface Fs indicated by phantom lines in FIGS. 1 and 3. The raised portions 9 have a front portion 9f formed continuously on the outer peripheral surface 3s of the head tip portion 3 and a rear portion 9r formed on the bottom surface 7d of the resin flow channel groove 7 or the outer peripheral surface of the small diameter shaft portion 4. Continuously formed for 4 s. That is, as shown in FIG.
The raised portion 9 and the outer peripheral surface 3s of the head tip 3 are made continuous with a curved surface, and the raised portion 9 and the bottom surface 7d of the resin flow channel groove 7 or the outer peripheral surface 4s of the small diameter shaft portion 4 are made continuous with a curved surface. .

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

First, at the time of measurement, the rotation of the screw 30 causes the resin on the screw main body Sm side to move forward, so that the ring valve 6 moves forward to the open position and the rear end of the head main body 2 (hard material). 11)
The resin on the screw main body Sm side is measured in front of the screw head portion 5 through the resin flow path space 8 and the resin flow path grooves 7. In FIG. 3, the arrow Ff indicates the flow of the resin. At this time, the resin flows inside the resin flow channel grooves 7. However, since the raised portions 9 exist on the bottom surfaces 7 d of the resin flow channel grooves 7, the space in which the resin stays is eliminated, and the resin flow is reduced. Since the stagnation is prevented and the effective cross-sectional area through which the resin passes in the middle portion of the resin flow channel groove 7 is relatively smaller than before and after, the resin in the middle portion of the resin flow channel groove 7. Is increased, and the stagnation hardly occurs. As a result, stagnation of the resin is effectively and sufficiently prevented, and deterioration of molding quality and defective molding due to deterioration of the stagnation resin are reliably eliminated.

At the time of injection, since the screw 30 moves forward, the ring valve 6 is moved rearward to the closed position by the resin weighed and accumulated in front of the screw head 5 to move to the front end (sheet) of the screw main body Sm. It contacts the ring 12). Thereby, the resin flow path space 8 is shut off.

FIG. 5 shows a modification of this embodiment. In a modified example, when the resin flow grooves 7 are provided, the resin flow grooves 7 are inclined at a predetermined angle Q with respect to the axis Fc direction of the screw head 5, preferably in a range of 12 to 15 °. The present embodiment differs from the embodiment shown in FIGS. 1 to 4 in that it is provided at Fa. In the modified example, the effect of preventing resin from staying is further enhanced. Note that other configurations and shapes in the modified example can be carried out in the same manner as in the embodiment shown in FIGS. Therefore, in FIG. 5, the same parts as those in FIG. 4 are denoted by the same reference numerals to clarify the configuration, and a detailed description thereof will be omitted.

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.

[0022]

As described above, in the screw head device of the injection molding machine according to the present invention, the bottom surface of the resin flow channel provided in the screw head portion is smaller than the outer peripheral surface of the small diameter shaft portion in which the ring valve is loaded. Since the raised portion which rises in an arc shape outward in the radial direction is provided, it is possible to effectively and sufficiently prevent the stagnation of the resin generated in the resin flow channel groove, thereby reducing the deterioration of the molding quality and the molding defect due to the deterioration of the accumulated resin. It has a remarkable effect that it can be reliably eliminated.

[Brief description of the drawings]

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

FIG. 2 is a front view of a screw head portion of the screw head device.

FIG. 3 is a diagram illustrating the operation of the screw head device.

FIG. 4 is a plan view showing a part of a screw head portion in the screw head device.

FIG. 5 is a plan view showing a part of a screw head portion in a screw head device according to a modification of the embodiment;

FIG. 6 is a partial cross-sectional side view of a screw head device according to the related art;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Screw head apparatus 2 Head main body part 3 Head tip part 3s Outer peripheral surface of head tip part 4 Small diameter shaft part 4s Outer peripheral surface of small diameter shaft part 5 Screw head part 6 Ring valve 7 ... Resin flow groove 7 d ... For resin flow path Bottom of groove 8 Space for resin flow passage 9 ... Upper part 9f ... Front part of upper part 9r ... Rear part of upper part Sm Screw body

Claims (5)

[Claims] 1. A screw head having a pointed head tip on the front side of a head body, a small diameter shaft having a predetermined length connected to the front end of the screw body on the rear side, A ring valve that is coaxially displaceable in the axial direction, and a plurality of resin flow grooves are provided at predetermined circumferential intervals on an outer peripheral surface from the head main body to the head tip. In a screw head device of an injection molding machine provided with a space for a resin flow path between a small diameter shaft portion and the ring valve, a bottom surface of the groove for a resin flow passage is disposed radially outward from an outer peripheral surface of the small diameter shaft portion. A screw head device for an injection molding machine, comprising a protruding upper portion that protrudes in an arc shape. 2. The method according to claim 2, wherein the raised portion has a front portion continuously formed on an outer peripheral surface of the head tip portion, and a rear portion formed continuously with a bottom surface of the resin flow channel groove or an outer peripheral surface of the small diameter shaft portion. The screw head device for an injection molding machine according to claim 1, wherein: 3. The screw head device for an injection molding machine according to claim 1, wherein said resin flow channel groove is provided in an axial direction of said screw head portion. 4. The screw head device for an injection molding machine according to claim 1, wherein said resin flow channel groove is provided in a direction inclined at a predetermined angle with respect to an axial direction of said screw head portion. 5. The screw head device for an injection molding machine according to claim 4, wherein said predetermined angle is set in a range of 12 to 15 °.