JPH0715319U - Thermosetting resin injection molding machine - Google Patents

Abstract

(57) [Summary] [Purpose] A thermosetting resin injection molding machine capable of performing injection molding while removing gas generated from the plasticizing material of the screw tip. [Structure] Between a hopper 11 and a raw material discharge port 5 of a thermosetting molding material of a heating cylinder 2 of an injection molding machine, a supply device 8 capable of adjusting a supply amount of a molding material is provided, and a screw 3 of a screw 3 is provided. Thermosetting resin injection molding machine with a drawing head 4 at the tip. [Effect] The gas generated from the plasticizing material at the tip of the screw escapes to the rear of the screw, and injection molding can be performed while removing the gas, so the surface of the molded product has a beautiful gloss that is not affected by gas. It is possible to obtain a dense product without voids inside the molded product.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a thermosetting resin injection molding machine capable of performing injection molding while removing a gas generated from a plasticizing material of a screw tip in injection molding of a thermosetting resin.

[0002]

[Prior art]

 Injection molding of thermosetting resin has conventionally been performed by a screw type injection molding machine. A hopper for supplying a molding material is provided at the rear of the heating cylinder of the injection molding machine, and the molding material from the hopper falls into the cylinder due to its own weight and is kneaded by the rotation of the screw, It is sent to the tip of the cylinder along the screw groove. The material in the cylinder is plasticized by the heat from the cylinder and the frictional heat generated by the kneading action of the screw. When the thermosetting resin is cured by heating, its chemical reaction (curing reaction) is an irreversible reaction. Therefore, the heating cylinder of the thermosetting resin not only heats the material, but also when necessary. Temperature control is performed so that the material is cooled and kept at a predetermined material temperature. The plasticized material stored in the tip portion of the screw is then injected into the mold. In thermosetting resin injection molding, after the material is filled into the mold, the mold clamping force is temporarily released and the mold dividing surface is opened for a few millimeters to discharge the gas in the cavity. Is being operated. In addition, since the thermosetting resin material has high viscosity during plasticization and little backflow of the plasticized material, the backflow prevention device often used in thermoplastic resin injection molding machines is used in thermosetting resin injection molding machines. The attached screw is not normally used.

[0003]

[Problems to be solved by the device]

 In injection molding of thermosetting resin, 90% or more of the causes of molding failure are due to gas generated from the material during molding. Therefore, the present invention is a thermosetting resin injection molding machine capable of performing injection molding in the injection molding of thermosetting resin while removing the gas generated from the plasticizing material at the screw tip. The task is to provide

[0004]

[Means for Solving the Problems]

 The present invention is a screw type thermosetting resin injection molding machine, in which it is possible to adjust the amount of molding material supplied between the hopper and the raw material drop opening of the heating cylinder in which the screw is rotatably and reciprocally inserted. And a squeezing head is provided at the tip of the screw.

In the conventional screw type thermosetting injection molding machine, a hopper is provided at the raw material dropping port of the thermosetting molding material of the cylinder of the injection molding machine, and the molding material supplied from the hopper flows inside the cylinder. Although it is fed forward by a screw in a clogged state, in the present invention, a feeding device capable of adjusting the feeding amount of the molding material between the hopper and the raw material dropping port of the thermosetting molding material of the heating cylinder. The molding material can be supplied little by little into the heating cylinder by the supply device. The molding material supplied into the cylinder is sent forward by the rotation of the main screw, but since the molding material is supplied little by little, the molding material is filled between the rear and middle screw grooves of the main screw. It is sent in a rough state. The material in the cylinder is gradually plasticized while being sent forward by the frictional heat generated by the heating from the cylinder and the kneading action of the screw. Volatile gas is generated from the plasticizing material at the tip of the screw, but the generated gas is rough because the molding material is in a rough state between the screw grooves in the middle and rear of the screw. Escapes from the middle part of the cylinder to the rear part and escapes from the raw material drop port. Therefore, in the injection molding machine of the present invention, it is possible to perform injection molding while removing the gas generated from the plasticizing material at the screw tip. Also, in a normal thermosetting resin injection molding machine, the material is clogged in the cylinder, and the thermosetting resin material has a high viscosity at the time of plasticization, so there is little risk of backflow of the plasticized material. There is no backflow prevention device at the tip of the screw. However, if the molding material between the screw grooves at the middle and rear of the screw is in a rough state, the plasticized material at the tip may flow backward. Since a throttling head, a so-called smear head, is provided, backflow of the plasticized material at the screw tip is prevented.

The thermosetting resin that can be molded by the injection molding machine of the present invention is phenol resin, urea resin, melamine resin, melamine-phenol resin, epoxy resin, diallyl phthalate resin and the like. These resins are mixed with a filler, a curing agent, a lubricant, etc. and used as a powdery or pelletized molding material. However, since the finely powdered molding material may be attached to the wall surface of the drop port by water droplets due to degassing of volatile components when it is supplied into the cylinder by the supply device, it is preferable that the molding material does not contain fine powder as much as possible. A particularly preferable molding material is a pellet having a particle diameter of 1 mm or more.

As a molding material supply device, a device having a feed screw incorporated therein and capable of adjusting the supply amount of the molding material in accordance with the number of revolutions of the feed screw is preferable. It is not limited. The compression ratio of the screw is 1.0 to 2.0. A high compression ratio is preferred to prevent backflow of the plasticized material. As the screw dimensional specifications, the screw pitch (P) of the screw is 0.8D to 1.0D, the screw depth (T) of the measuring portion is 1 / 8D to 1 / 12D with respect to the screw diameter (D). It is preferable that the aperture (H) of the aperture head is 1 / 20D to 1 / 40D and the seal length (L) of the aperture head is 3 / 8D to 7 / 8D. The screw diameter (D) is preferably in the range of 30 to 60 mm. Further, it is preferable that the cylinder head is made longer than usual so that when the molding material is hardened at the screw tip, the cylinder head can be removed to clean the diaphragm head.

[0008]

【Example】

 An embodiment of the present invention will be described with reference to FIG. In FIG. 1, 1 is a plasticizer of an injection molding machine, 2 is a heating cylinder of the injection molding machine, 3 is a main screw, 4 is a squeezing head (smear head), 5 is a raw material dropping port of a cylinder, and 6 is a cylinder head. , 7 is an injection nozzle, 8 is a molding material supply device, 9 is a feed cylinder, 10 is a feed screw, 11 is a hopper, and 12 is a gas vent. The thermosetting resin molding material filled in the hopper 11 is introduced from the hopper 11 into the feed cylinder 9 of the supply device 8. The molding material introduced into the cylinder is sent forward by the rotation of the feed screw 10, drops from the tip thereof, and enters the heating cylinder 2 of the injection molding machine through the raw material drop port 5 at the rear of the cylinder of the injection molding machine. Supplied. The supply amount of the molding material is adjusted by the rotation speed of the feed screw 10. The molding material supplied into the cylinder 2 of the injection molding machine is sent forward by the rotation of the main screw 3, but the molding material is not filled between the rear and middle thread grooves of the main screw 3 and is in a rough state. The molding material is supplied little by little so as to be sent by. Volatile gas is generated from the plasticized material at the tip of the screw 3, but the generated gas is rough because the molding material is in a rough state between the screw grooves at the middle and rear of the screw 3. Escapes to the rear part, escapes from the raw material dropping port 5, and is discharged to the outside of the device from a gas vent port 12 provided in the supply device 8 above it. In the figure, the arrow indicates the escape direction of gas. The compression ratio of the screw is 1.0 to 2.0, and a so-called smear head 4 is provided at the tip of the screw. In normal thermosetting resin injection molding, the material is clogged in the cylinder, and since the thermosetting resin material has a high viscosity at the time of plasticization, there is little risk of the material flowing backwards. If the molding material between the rear and rear groove portions is in a rough state, the plasticized material at the tip may flow backward, and the smear head 4 functions to prevent the material from flowing backward. Further, it is preferable to set a high compression ratio in order to throttle the generated gas and prevent backflow of the material. As an example of screw dimensional specifications, the screw diameter (D) = 40 mm, the screw thread pitch (P) is 0.9 D, the thread depth (T) of the measuring part is 1/10 D, and the gap of the iris head. (H) is 1 / 30D, and the seal length (L) of the diaphragm head is 5 / 8D. The plasticized material at the tip of the screw from which the generated gas is removed in this way is then injected from the injection nozzle 7 into the mold. The cylinder head 6 is made longer than usual, that is, extended to a position covering the smear head 4 so that the cylinder head 6 can be removed to clean the smear head when the molding material hardens at the tip of the screw. Is preferred.

[0009]

[Effect of device]

 In the thermosetting resin injection molding machine of the present invention, the gas generated from the plasticizing material at the tip of the screw is allowed to escape to the rear of the screw and injection molding can be performed while removing the gas. The surface of the molded product can have a beautiful gloss that is not affected by gas, and the inside of the molded product is a dense product without voids. It can also be formed from materials with high plasticizing torque.

[0010]

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of a thermosetting resin injection molding machine of the present invention.

[Explanation of symbols]

 1 Plasticizing device of injection molding machine 2 Heating cylinder of injection molding machine 3 Main screw 4 Drawing head 5 Cylinder raw material drop port 6 Cylinder head 7 Injection nozzle 8 Molding material supply device 9 Feed cylinder 10 Feed screw 11 Hopper 12 Degassing Mouth D Screw diameter P Screw thread pitch T Thread depth of measuring section H Gap of the drawing head L Seal length of the drawing head

Claims (3)

[Scope of utility model registration request] 1. In a screw type thermosetting resin injection molding machine, a supply amount of a molding material can be adjusted between a hopper and a raw material dropping port of a heating cylinder in which a screw is inserted so as to be rotatable and reciprocally movable. A thermosetting resin injection molding machine comprising a supply device and a drawing head provided at the tip of the screw. 2. The thermosetting resin injection molding according to claim 1, wherein a feed screw of the molding material is incorporated into the feeding device, and the feed amount of the molding material can be adjusted according to the rotation speed of the feed screw. Machine. 3. The screw has a compression ratio of 1.0-2.
0, the screw pitch (P) of the screw is 0.8D to 1.0D, the screw depth (T) of the measuring portion is 1 / 8D to 1 / 12D, and the gap of the diaphragm head ( The thermosetting resin injection molding machine according to claim 1, wherein (H) is 1 / 20D to 1 / 40D, and the seal length (L) of the aperture head is 3 / 8D to 7 / 8D.