JPH074017U - Injection device for thermosetting resin - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a thermosetting resin injection device in which backflow is unlikely to occur during injection. [Structure] Screw 1 with screw threads formed on the side surface
In a thermosetting resin injection device in which 2 is inserted into a heating cylinder 20 so as to be able to rotate and move forward and backward, the screw 12 is provided with a plunger portion 16 between a front end face 18 and a screw screw portion 14 rearward thereof. The inner diameter of the nozzle portion 26 at the front end of the heating cylinder 20 facing the plunger portion at the forward position of the screw is made substantially equal to the outer diameter of the plunger portion 16 so that the outer peripheral surface of the plunger portion 16 of the screw is the nozzle when the screw is forward. The inner peripheral surface 27 of the part is almost in contact with.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a thermosetting resin injection device, and more particularly to a thermosetting resin injection device that uses a screw front portion as a plunger.

[0002]

[Prior art]

 In a conventional thermosetting resin injection device, as shown in FIG. 3, a screw 50 is inserted into a heating cylinder 40 so as to be rotatable and movable forward and backward. The screw 50 described above has a screw end portion 52 having a substantially conical shape, and has a screw thread portion 54 formed with a screw thread on a side surface thereof. This screw 50 transfers the thermosetting resin 60 supplied in the heating cylinder 40 to the front by the rotation of the screw 50 while plasticizing the thermosetting resin 60 by the heat of the heating cylinder 40, kneading at that time, and at a predetermined amount. After the transfer (measurement), the plastic thermosetting resin is injected by advancing the screw 50. In the illustrated heating cylinder 40, the inner peripheral surface 44 of the nozzle portion 42 at the front end is formed into a substantially conical shape matching the front end surface 52 of the screw 50, and the inner diameter of the rear inner surface 46 is made substantially equal to the screw diameter. There is.

By the way, in a thermoplastic resin injection device, a check valve may be provided at the front end of the screw, whereas in a thermosetting resin injection device, a check valve is usually not provided at the screw front end. A screw screw portion 54 is formed up to the rear portion of the front end face 52. This is because the thermosetting resin raw material turns into a plastic state once by heating, but it does not plasticize again even if it is heated again after being cured after it has been cured over time and once cured. This is because if the screw is provided at the tip of the screw, if the plastic thermosetting resin stays in the vicinity of the check valve, it will cure as it is and the screw will no longer be usable.

However, since the thermosetting resin injection device does not have a check valve, the plastic thermosetting resin during injection (during forward movement of the screw) causes the plastic thermosetting resin to contact the inner peripheral surface of the nozzle of the heating cylinder and the front end of the screw. It is easy to flow backward from the clearance 56 between the surfaces to the rear of the screw through the clearance between the heating cylinder inner peripheral surface and the screw mountain behind, and the injection amount changes with each shot, or the injection pressure is not sufficiently transmitted to the mold. However, there is a problem that molding defects are likely to occur. Further, there is a problem that the screw is easily worn due to the backflow at the time of injection.

[0005]

[Problems to be solved by the device]

 Therefore, the present invention has been made in view of the above points, and provides an injection device for a thermosetting resin that hardly causes backflow.

[0006]

[Means for Solving the Problems]

 This invention is a thermosetting resin injection device in which a screw having a screw screw formed on the side surface is inserted into a heating cylinder so that the screw can be rotated and moved forward and backward. A plunger portion is provided on the front surface of the heating cylinder or the nozzle portion facing the plunger portion at the forward position of the screw so that the inner diameter of the nozzle portion is substantially equal to the outer diameter of the plunger portion. The thermosetting resin injection device is characterized in that the outer peripheral surface of the portion is substantially in contact with the front end portion of the heating cylinder or the inner peripheral surface of the nozzle portion. In this invention, the term "screw screw portion" refers to a range portion where the screw screw is formed.

[0007]

[Action]

 The thermosetting resin injection device of the present invention operates as follows. The thermosetting resin supplied into the heating cylinder is plasticized in the heating cylinder, kneaded by the rotation of the screw, and transferred to the front of the heating cylinder. Then, after being transferred by a predetermined amount, the forward movement of the screw causes the plastic resin at the front end of the heating cylinder to be pushed by the screw and injected into the mold. At that time, the outer peripheral surface of the plunger at the front part of the screw is almost in contact with the front end of the heating cylinder or the inner peripheral surface of the nozzle, and the outer peripheral surface of the plunger and the tip of the heating cylinder or inner peripheral surface of the nozzle are almost closed. Since the plastic thermosetting resin in front of the screw is pushed forward, there is almost no risk that the resin will flow backwards to the rear of the screw.

[0008]

【Example】

 Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a sectional view of an injection device for thermosetting resin according to an embodiment of the present invention, and FIG. 2 is an enlarged sectional view of a main part at the time of injection.

In the injection device 10, the screw 12 is inserted into the heating cylinder 20, and a screw driving device (not shown) is connected to the rear portion of the screw 12, so that the screw 12 is rotated and moved forward and backward. . The screw 12 is for kneading, measuring, and injecting a thermosetting resin, and has a screw screw portion 14, a plunger portion 16, and a front end face 18. The screw screw portion 14 is a portion where a screw screw is formed on the side surface of the screw 12. The screw ridge 15 of the screw screw portion 14 is gentle and disappears before the plunger portion 16.

The plunger portion 16 is located between the screw thread portion 14 and the front end face 18, and has an outer diameter b which is equal to the root diameter a of the screw thread portion 14 in this embodiment. The length d of the plunger portion 16 is preferably about 1/2 to 1/4 of the screw diameter. Although the plunger portion 16 is integrated with the screw thread portion 14 in this embodiment, it may be screwed to the front end of the screw thread portion 14 so as to be replaceable. Further, the screw front end surface 18 is a surface that constitutes the front end of the screw 12, and is substantially conical in this embodiment.

The heating cylinder 20 is for heating a thermosetting resin to plasticize it. In the heating cylinder 20 of this embodiment, a jacket 22 for circulating the temperature control medium is provided as a heating means on the peripheral wall portion. The rear part of the heating cylinder 20 is provided with a raw material charging hopper 24 having an open upper surface.

The front end of the heating cylinder 20 serves as a nozzle portion 26 for introducing the plastic thermosetting resin into the mold. The inner peripheral surface of the nozzle portion 26 is shaped to conform to the outer peripheral surface of the plunger portion 16 and the front end surface 18 of the screw 12, and the inner diameter c of the portion 27 facing the plunger portion 16 when the screw 12 is in the forward position. Is approximately equal to the outer diameter b of the plunger portion 16, preferably 0.1 to 0. It is enlarged by about 3 mm. Further, the inner diameter of the heating cylinder 20 behind the nozzle portion 26 is made substantially equal to the screw diameter. 28 is a nozzle hole.

The injection device 10 thus configured operates as follows during injection molding. First, the thermosetting resin 30 as a raw material is put into the raw material feeding hopper 24. As the thermosetting resin 30, a rubber material can be used in addition to the pure thermosetting resin.

The thermosetting resin 30 charged in the raw material charging hopper 24 is introduced to the rear part of the screw 12 in the heating cylinder 20, and is fed forward in the heating cylinder 20 by the rotation of the screw 12. At that time, the thermosetting resin 30 is heated by the heat medium of the jacket 22 on the peripheral wall of the heating cylinder 20 to become plastic. The heating temperature at this time is set to the temperature at which the thermosetting resin raw material used is plasticized.

After a predetermined amount of the plastic thermosetting resin has been sent (measured) to the front end of the heating cylinder 20 by the rotation of the screw 12, the outer peripheral surface of the plunger portion 16 of the screw 12 is almost the same as the inner peripheral surface 27 of the nozzle portion 26. While advancing, the plastic thermosetting resin at the front end of the heating cylinder is injected into the mold from the nozzle hole 28 of the nozzle portion 26. At the time of injection, the screw 12 moves forward while pushing the outer peripheral surface of the plunger portion 16 of the screw 12 and the inner peripheral surface 27 of the nozzle portion 26 and pushes the plastic thermosetting resin forward. There is almost no risk of backward flow. The plastic thermosetting resin injected into the mold cures into a molded product.

In the above-mentioned embodiment, the case where the inner peripheral surface of the nozzle portion faces the plunger portion of the screw has been shown, but the present invention is not limited to this, and the inner peripheral surface of the front end portion of the heating cylinder is It may be opposed to the plunger portion of the screw.

[0017]

[Effect of device]

 As shown and described above, in the thermosetting resin injection device of the present invention, the inner peripheral surface of the front end of the heating cylinder or nozzle and the outer peripheral surface of the plunger at the front of the screw are almost in contact with each other during injection. Since the screw advances, there is almost no backflow of thermosetting resin during injection. As a result, the injection amount is stable, and the injection pressure is sufficiently applied to the mold, so that favorable molding can be performed, and the abrasion of the screw due to the reverse flow at the time of injection can be eliminated. Also, the provision of the plunger portion has the advantage that the injection pressure can be made higher than that of a normal screw.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a thermosetting resin injection device according to an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view showing a main part of the injection device during injection.

FIG. 3 is a cross-sectional view of a conventional thermosetting resin injection device.

[Explanation of symbols]

10 Thermosetting Resin Injection Device According to One Embodiment of the Invention 12 Screw 14 Screw Screw Part 16 Plunger Part 18 Front End Face 20 Heating Cylinder 26 Nozzle Part 27 Nozzle Inner Perimeter Face of Plunger Part at Screw Advance Position

Claims (1)

[Scope of utility model registration request] 1. A thermosetting resin injection device in which a screw having a screw screw formed on a side surface is inserted into a heating cylinder so that the screw can rotate and move forward and backward, the screw includes a front end face and a screw screw portion behind the screw. A plunger portion is provided between the heating cylinder front end portion and the nozzle portion facing the plunger portion at the forward position of the screw, and the inner diameter of the nozzle portion is substantially equal to the outer diameter of the plunger portion, and the plunger portion of the screw at the time of advancing the screw. The thermosetting resin injection device is characterized in that the outer peripheral surface is substantially in contact with the front end portion of the heating cylinder or the inner peripheral surface of the nozzle portion.