JPH0453934Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an injection molding machine equipped with a raw material supply device into which a feed screw is rotatably inserted for supplying raw materials.

(Prior Art) In conventional main screws, the feed zone is relatively long, and the raw material supply device for supplying raw materials to the feed zone of the main screw does not include heating means.

(Problem to be solved by the invention) However, in injection molding machines where the feed zone of the main screw is relatively long and the raw material supply device is not equipped with a heating means, gas release during metering is difficult or as the main screw retreats. Some of the raw materials supplied at the front of the feed zone do not receive sufficient preheating from the heating cylinder and are subjected to rapid shearing at a relatively low temperature in the compression zone, causing extreme heat generation and causing resin burns, etc. Problems may occur.

(Means for Solving the Problems) The present invention has been made against the background of the above, and the length of the feed zone of the main screw is 3d to 8d when the outer diameter of the main screw is d.
In addition, the raw material supply device is provided with heating means for preheating the raw material to a maximum temperature close to the melting temperature.

(Example) Examples will be described according to the drawings.

In FIG. 1, 1 is the bed of an injection molding machine, and 2 is an injection device mounted on the bed 1. In FIG.

3 is a housing of the injection device, and 4 is a heating cylinder which is fixed to the housing 3 by a flange 5 via a threaded portion 4B.

A main screw 6 is inserted into the heating cylinder 4 so that it can rotate and reciprocate. Furthermore, M written on the drawing
is the metering zone of the main screw 6, C is the compression zone, and F is the feed zone. A screw head portion 7 is provided at the tip of the main screw.
is provided. Many types of screw head portions 7 are known, but in this example a ball check type check valve unit is adopted.

Reference numeral 8 denotes a cylinder head having an inner hole with a conically reduced diameter at a position facing the screw head portion 7, and is fastened to the tip of the heating cylinder 4 by a plurality of bolts 8A.

A nozzle 9 is screwed onto the cylinder head 8. The cylinder head and the nozzle may also be fabricated as one piece.

Reference numeral 10 denotes a plurality of band heaters provided around the outer periphery of the heating cylinder 4. Band heaters 11 and 12 are provided on the outer periphery of the cylinder head 8, and band heaters 13 are provided on the outer periphery of the nozzle 9, respectively.

Reference numeral 14 denotes a raw material supply device for supplying raw materials from the raw material supply port 4A of the heating cylinder 4 to the main screw 6.

15 is a feed cylinder of the raw material supply device 14.

15A is an inner hole passing through the feed cylinder 15, and 15B is a raw material supply hole communicating with the inner hole 15A. A first bearing hole 15C is formed from one end (the right end in this figure) of the inner hole 15A, and a second bearing hole 15D is formed from the other end on the same axis as the inner hole 15A.

A connector 16 is rotatably supported by a plurality of bearings 17. 18 is the first bearing hole 15C
It is a resin bush that is inserted into the connector 16, and there is a slight clearance close to zero between the inner periphery of the bush 18 and the outermost periphery of the connector 16, and the width of the bush 18 is equal to the outermost periphery of the connector 16. The dimensions are approximately 1mm larger than the width of the .

Reference numeral 15E indicates a leg portion of the feed cylinder 15, and the lower outer periphery of the leg portion 15E has a flange shape, and the feed cylinder 15 is fastened to the heating cylinder 4 by a plurality of bolts passing through the flange shape portion. Ru.

15F is a raw material fall hole, which extends from the top of the feed cylinder 15 at right angles to the inner hole 15A and extends through the leg portion 15E.
The upper part opens to the outside, and the lower part opens to the raw material supply port 4A of the heating cylinder 4. The inner diameter of the raw material drop hole 15F is slightly smaller than or the same diameter as the inner diameter of the raw material supply port 4A.

Reference numeral 19 denotes a bracket erected on the housing 3, and the right side of the feed cylinder 15 and the variable speed electric motor 20 are fixed to the bracket 19 while being centered. A drive shaft (not shown) of the variable speed electric motor 20 is fitted into a boss hole (not shown) of the connector 16 to transmit the output of the variable speed electric motor to the connector 16 via a key (not shown). ing. 21 is a feed screw inserted into the inner hole 15A, and one end is connected to the connector 16.
The connector 1
6 is detachably fitted and supported without any play, and the other end is supported by a bearing 22 fitted into the second bearing hole 15D. The feed screw 21
For example, when the length of M of the main screw 6 is 4d, the length of C is 6d, and the length of F is 7d (where d is the outer diameter of the main screw 6),
Same shape as F of main screw 6, same 6d~7d
It can be of a certain length. 23 is a resin bushing inserted into the second bearing hole 15D;
The inner peripheral surface of the bush 23 and the feed screw 21
There is a clearance close to zero between the outer circumferential surfaces of the two. Reference numeral 24 is a removable pressing flange whose outer edge can come into contact with the outer ring of the bearing 22.

25 is a lid fitted into the upper opening of the aforementioned raw material drop hole 15F. A gas vent hole 25A can be provided through the center of the lid 25. This gas vent hole 25A can also be made blind by a plug.

26 is a plurality of band heaters provided on the outer periphery of the feed cylinder 15.

27 is the raw material supply hole 15 of the feed cylinder 15
This is a hopper for storing raw materials supplied to the feed screw 21 through B.

The operation will be explained.

FIG. 1 shows a state in which injection is completed and the main screw 6 is at its forward limit position.

At the same time as the main screw 6 inserted into the heating cylinder 4 starts rotating, the variable speed electric motor 20 of the raw material supply device 14 is started. The output of the variable speed electric motor 20 is transmitted to the feed screw 21 via the connector 16, and the feed screw 21 rotates at a preset rotation speed. The raw material stored in the hopper 27 is transferred to the left in the drawing by the rotation of the feed screw 21. At this time, the raw material is preheated by a plurality of band heaters provided around the outer periphery of the feed cylinder 15. The preheating temperature is set to an arbitrary temperature with the highest limit being close to the melting temperature of the raw material, and is feedback controlled. The preheated raw material transferred to the left side of the feed cylinder naturally falls through the raw material drop hole 15F and reaches the raw material supply port 4A of the heating cylinder 4.
The feed zone F of the main screw 6 is supplied from the feed zone F of the main screw 6. The raw material supplied to the feed zone F of the main screw 6 is transferred to the front of the screw head 7 while being heated and melted by a plurality of band heaters 10 provided on the outer periphery of the heating cylinder 4.

Since the raw material is preheated by the raw material supply device, it is not subjected to sudden shearing in the compression zone C, and the length of the feed zone F of the main screw 6 is set to 7d for the gas generated when the raw material is melted. Therefore, the raw material can be easily discharged from the rear of the feed zone F of the main screw 6 to the outside through the gas vent hole 25A of the lid 25 through the raw material supply port 4A and the raw material drop hole 15F.

As the almost ideally melted raw material accumulates in front of the screw head 7, the main screw 6 moves back accordingly, and when a predetermined metering is completed, the main screw 6 stops rotating.

When the main screw 6 stops rotating, the feed screw 21 of the raw material supply device 14 also stops rotating.

Next, in the injection stroke, the melted and metered raw material is injected by the forward movement of the main screw 6 through the nozzle 9 into a mold cavity (not shown) on the mold clamping side.

Immediately after the injection stroke ends, or after a preset time has elapsed, the main screw 6 rotates again and begins melting and metering the raw material for the next cycle.

Next, a second embodiment will be explained with reference to FIG. 1
00 is a raw material supply device having a heating means different from the raw material supply device 14 in FIG.

Reference numeral 200 is a feed screw of the raw material supply device 100, and an insertion hole 2 is a deep hole with a bottom that is bored in the feed screw 21 in FIG. 1 from the left side in the drawing to near the base of the screw.
00A is provided.

On the other hand, a presser flange 500, which has a through hole at the center of the presser flange 24 shown in FIG.

300 has a mounting flange portion at the left end, and the tip thereof is attached to the feed screw 20 when mounted.
It is a bottomed pipe-shaped sliding heat transfer member that reaches the bottom of the insertion hole 200A, and its outer diameter is the same as that of the insertion hole 200A.
The inner diameter is such that the outer diameter of the cartridge heater 400 can be inserted into the cartridge heater 400 with almost no clearance. The cartridge heater 400 has an attachment flange portion at the left end, and the tip thereof reaches the bottom of the sliding heat transfer member 300 when attached.

That is, the heating means of the raw material supply device 100 is such that a sliding heat transfer member 300 is inserted into the insertion hole 200A of the feed screw 200, and a cartridge heater 400 is inserted into the sliding heat transfer member 300. A sliding heat transfer member 300 is attached to a presser flange 500 fixed to the cylinder 15 with bolts.
A cartridge heater 400 is attached to the flange portion of the fixed sliding heat transfer member 300.
The flange part is fixed. Therefore, the operation is such that when the feed screw 200 rotates simultaneously with the main screw 6, the feed screw 200 rotates and slides the insertion hole 200A of the feed screw 200 around the outer periphery of the fixed sliding heat transfer member 300, and the cartridge heater 400
It will be heated by the transfer of output electric heat.

In the second embodiment, no band heater is provided around the outer periphery of the feed cylinder.

As mentioned above, the second embodiment differs from the first embodiment only in the heating means of the raw material supply device, and the rest is completely the same as the first embodiment, so a description thereof will be omitted.

Although two embodiments of the present invention have been described above, the present invention can be implemented in various ways without departing from the spirit thereof. A band heater is provided on the outer periphery of the feed cylinder, and in the second embodiment, a cartridge heater is provided inside the feed screw. It is also possible to provide a cartridge heater in addition to the cartridge heater.

(Functions and Effects) According to the present invention, the length of the feed zone of the main screw is set to 3d to 8d, and the raw material supply device is provided with a heating means for preheating the raw material to a maximum temperature close to the melting temperature. This makes it possible to supply the preheated raw material relatively close to the compression zone of the main screw, thereby preventing the raw material from being subjected to extreme shearing during melting and metering, thereby preventing problems such as resin burning. In addition, the length of the feed zone of the main screw is approximately 1/2 of the normal length, making it easier for gas to escape from the rear of the main screw, and the short feed zone shortens the time required for color changes. There is also.

Furthermore, by shortening the main screw, its weight and inertia are reduced, making it possible to control injection speed and accurate control of the screw stop position, and to make the overall length of the machine shorter and more compact.

[Brief explanation of the drawing]

FIG. 1 is a front view of essential parts for explaining the first embodiment of the present invention, and FIG. 2 is a partial view for explaining the second embodiment. 4... Heating tube, 6... Main screw, F... Feed zone (main screw), 14... Raw material supply device, 15... Feed cylinder, 20... Variable speed electric motor, 21... Feed screw, 26... Band heater, 100... Raw material supply device, 200...
...Feed screw, 200A...Insertion hole, 30
0...Sliding heat transfer member, 400...Cartridge heater, 500...Pushing flange.

Claims (1)

[Scope of utility model registration request] In an injection molding machine equipped with a raw material supply device in which a main screw is rotatably and reciprocatably inserted into a heating cylinder, and a feed screw for supplying raw materials to the main screw is rotatably inserted into a feed cylinder, A heating means for setting the length of the feed zone of the main screw to be 3d to 8d when the outer diameter of the main screw is d, and preheating the raw material to the raw material supply device with a maximum temperature close to the melting temperature. An injection molding machine characterized by being equipped with.