JPH11129299A - 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 in 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 provided between the small diameter shaft part 4 and the ring valve 6. At least the back parts 7r of the channels for the resin flow paths 7 are formed gradually wider toward the back end side.

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. 5 shows a general screw head device 50 provided in an injection molding machine. In the figure, reference numeral 60 denotes a screw loaded in 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 on the rear side of 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. 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 reference 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 particular, at least the rear portion 7r of the resin channel groove 7.
.. Are formed gradually wider toward the rear end.

In this case, according to a preferred embodiment, of the plurality of head divisions 9 formed between the resin flow channel grooves 7, every other one of the head divisions 9 in the circumferential direction is formed. Is formed into a specific dividing portion 9m, and each of the groove wall surfaces 10x, 10y on both sides of the specific dividing portion 9m is formed in a cut shape, so that the resin flow channel grooves 7 are formed gradually wider toward the rear end side. . In addition, the rear end face 9m ...
Are located forward of the rear end faces 9r of the adjacent head divisions 9 and the rear end faces 9r of the head divisions 9.
Are hardened by hard materials 11 using stellite, boron alloy, cobalt alloy or the like. On the other hand, the resin channel grooves 7 are provided at a predetermined angle Q with respect to the direction of the axis Fc of the screw head 5, preferably in a direction inclined at 12 to 15 °. Further, the bottom surface 7d of the resin flow channel groove 7 ...
It is desirable to provide a raised portion 12 that rises in an arc shape radially outward from the outer peripheral surface 4s of the small-diameter shaft portion 4. The raised portions 12 have a front portion 12f formed continuously on the outer peripheral surface 3s of the head tip portion 3 and a rear portion 12r.
Are continuously formed on the bottom surface 7d of the resin flow channel groove 7 or the outer peripheral surface 4s of the small diameter shaft portion 4.

As a result, at least the rear portion 7r of the resin flow channel groove 7 gradually widens toward the rear end, so that the resin flowing into the resin flow channel groove 7 from the rear during the measurement is As the width of the grooves 7 becomes narrower, the flow velocity and the flow pressure are increased, and the stagnation of the resin which tends to occur on the front side of the resin flow grooves 7 is prevented. On the other hand, each of the groove wall surfaces 10x and 10y on both sides of each of the specific dividing portions 9m is formed into a cutting shape, and the rear end surfaces 9mr of the specific dividing portions 9m are rear end surfaces 9r of the adjacent head dividing portions 9 ... If it is located further forward, the grooves 7 for the resin flow paths are left-right asymmetric, and the resin is diverted to the left and right by the rear end faces 9mr... The flow of the resin in the grooves 7 is changed, and the resin hardly stays from this side surface. If the rear end surfaces 9r of the head dividing portions 9 are hardened by the hard material 11, the head body 2
The contact area of the ring valve 6 on the rear end face is reduced by half as compared with the related art. If the resin flow grooves 7 are provided at a predetermined angle Q with respect to the direction of the axis Fc of the screw head portion 5, and preferably in a direction inclined at a range of 12 to 15 °, the resin flow grooves 7 can also be formed from this side surface. The resin in the road grooves 7 hardly stays. Further, the bottom surfaces 7d of the resin flow grooves 7 ...
Is provided with a raised portion 12 that rises in an arc shape radially outward from the outer peripheral surface 4s of the small-diameter shaft portion 4, the space in which the resin stagnates in the resin flow channel groove 7 becomes the raised portion 9. , The space where the resin stays is eliminated,
Also from this side, the stagnation of the resin is prevented. In addition, since the effective cross-sectional area through which the resin passes in the middle portion of the resin flow channel 7 becomes relatively smaller than before and after due to the raised portions 9, the rear portion 7 r of the resin flow channel 7. Is gradually increased toward the rear end side, the flow velocity of the resin is increased toward the front of the resin flow channel grooves 7..., And the resin hardly stays from this side surface.

[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 extending from the main body 2 to the head end 3 has a plurality of resin passage grooves 7 at predetermined intervals in the circumferential direction. In this case, as shown in FIG. 1, the resin flow channel grooves 7 are provided in a direction Fa inclined at a predetermined angle Q with respect to the axis Fc direction of the screw head portion 5, preferably in a range of 12 to 15 °.

At least the rear portions 7r of the resin flow channel grooves 7 are formed so as to gradually become wider toward the rear end. In particular,
Of the plurality of head divisions 9 formed between the resin flow channel grooves 7, every other head division 9 in the circumferential direction
Are formed into a specific shape 9m, and the groove walls 10x and 10y on both sides of the specific shape 9m are respectively formed in a cut shape so that the rear portion 7r of the resin flow channel groove 7 becomes closer to the rear end. Formed gradually wide.

Further, the rear end faces 9mr of the three specific shaped parts 9m are located forward of the rear end faces 9r ... of the three adjacent head shaped parts 9, and the rear end faces 9mr and the rear end faces 9mr. An offset L as shown in FIG.
Cause. Thereby, even if the ring valve 6 moves forward and abuts on the head main body 2, even if the rear end faces 9 r. The rear end faces 9mr are non-contact.

On the other hand, on the bottom surfaces 7d of the resin flow channel grooves 7, there are provided raised portions 12 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 12 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. Also,
The raised portions 12 have a front portion 12f formed continuously on the outer peripheral surface 3s of the head tip portion 3 and a rear portion 12r formed on the bottom surface 7d of the resin flow channel groove 7 or the outer peripheral surface 4s of the small diameter shaft portion 4. Form continuously. That is, as shown in FIG. 4, the raised portions 12 and the outer peripheral surface 3s of the head end portion 3 are continuously formed by a curved surface, and the raised portions 12 and the bottom surfaces 7d of the resin flow grooves 7 or the small-diameter shaft portion 4 are formed. Is made continuous by a curved surface.

On the other hand, 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 surfaces 9r of the head dividing portions 9 described above are formed on inclined surfaces that are in surface contact with the tapered surfaces. The ring valve 6 is mounted coaxially with the small diameter shaft portion 4 so as to be displaceable in the axial direction. Thereby, a resin flow passage space 8 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 surface thereof is formed into a head dividing portion 9. , The resin flow path space 8 is opened, and the ring valve 6 is opened.
Is displaced rearward, the rear end abuts on the front end of the screw body Sm, and the resin flow path space 8 is shut off.

Further, the rear end faces 9r of the head dividing portions 9 contacting the ring valve 6 and the front end face of the screw body Sm may be worn out by the contact of the ring valve 6.
For this reason, the rear end faces 9r of the head dividing portions 9 are made of a hard material 11 made of stellite, boron alloy, cobalt alloy or the like.
Are hardened by welding or the like, and a donut-shaped seat ring 13 formed of the same material as the hard material 11 is attached to the front end surface of the screw body Sm.

Next, the operation and function 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 body Sm side to move forward, so that the ring valve 6 moves forward to the open position and the rear end face 9r of the head dividing section 9. (Hard material 11 ...), and the resin on the screw body Sm side passes through the resin flow path space 8 and the resin flow path grooves 7 ... and the screw head 5
Is weighed in front of In FIG. 4, the arrow Ff indicates the flow of the resin. At this time, the resin enters the resin channel grooves 7 and flows forward in the resin channel grooves 7. However, the resin is diverted by the rear end faces 9 mr. The left and right asymmetric shape of each resin flow channel groove 7 changes the flow of the resin in each resin flow channel groove 7 in the left-right direction, so that the resin hardly stays. Moreover, since the space where the resin stays in the resin flow channel grooves 7 is filled with the raised portions 12, the space where the resin stays is eliminated, and the resin is prevented from staying from this side surface. 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 12, the rear portion 7 of the resin flow channel groove 7.
The width of the resin flowing through the resin flow channel grooves 7 is increased in the forward direction by combining r with... gradually increasing in width toward the rear end, so that the resin hardly stays from the side surfaces. Therefore, stagnation of the resin is effectively and sufficiently prevented, and deterioration in molding quality and molding defects 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 13). Thereby, the resin flow path space 8 is shut off.

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.

[0023]

As described above, in the screw head device of the injection molding machine according to the present invention, basically, at least the rear portion of the groove for the resin flow passage provided in the screw head portion is formed gradually wider toward the rear end side. Has the following remarkable effects.

[0024] Residual resin generated in the resin flow channel groove can be effectively and sufficiently prevented, so that deterioration in molding quality and defective molding due to deterioration of the retained resin can be reliably eliminated.

According to a preferred embodiment, the respective groove wall surfaces on both sides of each specific part are formed in a cut shape, and the rear end face of the specific part is located forward of the rear end face of the adjacent head part. If this is done, the resin will be diverted by the rear end face of the specific dividing portion, and then flow through the left-right asymmetric resin flow grooves, so that the resin flow in each resin flow groove will change in the left-right direction. This makes it difficult for the resin to stay from this side surface.

According to a preferred embodiment, if a raised portion is formed on the bottom surface of the resin flow channel groove so as to rise in an arc shape radially outward from the outer peripheral surface of the small-diameter shaft portion, the resin flow channel groove is formed. Since the space where the resin stays is filled by the upper portion, the space where the resin stays is eliminated, so that the resin can be prevented from staying from this side surface. Since the effective cross-sectional area that passes is relatively small compared to the front and rear, the resin is formed by gradually increasing the width of the rear portion of the groove for the resin flow path toward the rear end, so that the resin becomes The flow velocity is increased as going forward, so that the resin can hardly stay from this side surface.

[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 cross-sectional rear view of a screw head portion in the screw head device.

FIG. 3 is a partial cross-sectional plan view of the screw head device,

FIG. 4 is an operation explanatory view of the screw head device;

FIG. 5 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 device 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 channel groove 7r ... Resin channel Rear of groove 7d Bottom of resin flow channel groove 8 Space for resin flow channel 9 Head division 9r Rear end of head division 9m Specific division 9mr Rear end surface of specific division 10x Groove wall surface 10y Groove wall surface 11 Hard material 12 Upper part 12f Front part of upper part 12r Rear part of upper part Sm Screw body

Claims (8)

[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 resin passage space between a small diameter shaft portion and the ring valve, at least a rear portion of the resin passage groove is formed to be gradually wider toward a rear end side. Screw head device of injection molding machine. 2. A plurality of head divisions formed between the resin flow channel grooves, each head division at every other circumferential direction being a specific division, and each head division at both sides of the specific division. 2. The screw head device for an injection molding machine according to claim 1, wherein the groove for the resin flow path is formed gradually wider toward the rear end side by forming each of the groove wall surfaces into a cut shape. 3. The screw head device for an injection molding machine according to claim 2, wherein a rear end face of said specific shaping portion is located forward of a rear end face of an adjacent head shaping portion. 4. The screw head device for an injection molding machine according to claim 2, wherein a rear end face of said head shaping portion is hardened by a hard material using stellite, boron alloy, cobalt alloy or the like. 5. 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. 6. The screw head device for an injection molding machine according to claim 5, wherein said predetermined angle is set in a range of 12 to 15 °. 7. The injection molding according to claim 1, wherein a raised portion is formed on the bottom surface of the groove for the resin flow passage so as to rise in an arc shape radially outward from the outer peripheral surface of the small diameter shaft portion. Screw head device. 8. The embossed portion has a front portion continuously formed on an outer peripheral surface of the head end portion, and a rear portion formed continuously with a bottom surface of the resin flow channel or an outer peripheral surface of the small diameter shaft portion. The screw head device for an injection molding machine according to claim 7, wherein: