JP2002096367A - Heating cylinder for injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heating cylinder for an injection molding machine in which when accompanied with using the heating cylinder for a long time, the inner wall of the heating cylinder is worn and the heating cylinder is exchanged, it is enough that only a heating head is exchanged and expenditure for the work can be reduced and the work for exchange is easily performed and even when a resin material is solidified in the heating cylinder, unnecessary articles can be removed. SOLUTION: In the heating cylinder 1 for the injection molding machine constituted of a heating cylinder being separable to a heating cylinder main body 2 and the heating cylinder head 3, the connecting part on the heating cylinder side of the heating cylinder head 3 is a long cylinder 12 with a ratio of the cylindrical inner diameter to the length in the connecting direction of approximately 1 versus 16 and a male screw channel 13 is cut at the apex of the outside wall of the long cylinder 12 and a female screw channel corresponding to the male screw channel 13 is cut on the inside wall of a receiving cylinder 14 into which the long cylinder 12 on the heating cylinder side of the heating cylinder main body 2 is correspondingly inserted and screw-fixed and for the heating cylinder 1, the long cylinder 12 of the heating cylinder head 3 is inserted into the receiving cylinder of the heating cylinder main body 2 and the male screw channel 13 of the heating cylinder heat 3 is screw-fixed with the female screw channel 15 of the heating cylinder main body 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a heating cylinder for an injection molding machine which is improved so that the heating cylinder does not need to be replaced even if the heating cylinder wears as the frequency of use of the injection molding machine increases. The present invention relates to a heating cylinder of an injection molding machine in which only the heating cylinder head can be replaced.

[0002]

2. Description of the Related Art Usually, one heating cylinder is used in an injection molding machine. When a molding machine using this heating cylinder uses a thermoplastic resin, it is necessary to attach a backflow prevention mechanism to the tip of the screw inside the heating cylinder.

FIG. 5 is a schematic diagram showing the tip of a conventional general injection molding machine, that is, the relationship among a nozzle, a heating cylinder head, a heating cylinder, a screw, and a backflow prevention ring.
Here, as shown in FIG. 5, a male screw groove is cut on the outer wall of the annular bulging portion at a joint portion on the heating cylinder side of the heating cylinder head, while a female screw groove corresponding to the male screw groove is heated. It is cut into the inner wall of the recessed recess at the tip of the cylinder body,
The heating cylinder has an external thread groove of the heating cylinder head screwed into a female thread groove provided at the tip of the heating cylinder main body, and a bolt hole formed at the flange portion of the heating cylinder head and the distal end of the heating cylinder main body. After the positioning, the above two parts are joined by bolting.

At this time, the backflow preventing ring is used to prevent the resin once injected from flowing back to the screw side when the resin melted in the heating cylinder is injected from the nozzle into the mold by a screw and the pressure is particularly maintained. Things. FIG.
In the structure of the tip of a conventional injection molding machine as
The backflow prevention ring is mounted with a little play behind the screw spire loaded at the tip of the screw, and these screws recede along the inner wall of the heating cylinder main body at the time of material measurement, and the resin At the time of injection, the screw spire is advanced to a position where the screw spire comes into contact with a substantially funnel-shaped bottom surface formed in the heating cylinder head. Further, as shown in the figure, at the most advanced position at the time of holding pressure where the resin filling pressure is most applied to the heating cylinder head and the heating cylinder main body, the tip of the backflow prevention ring is connected to the heating cylinder main body and the heating cylinder head. It can be seen that they are designed to match. This is because the inner wall of the heating cylinder main body in which the screw with high temperature and high pressure repeats advancing and retreating with prolonged use, the inner wall expands due to wear, and the outer dimensions almost match the inner diameter dimensions of the heating cylinder main body When the backflow prevention ring, which is designed in such a manner and receives the high resin filling pressure of the holding pressure, repeatedly slides on the joint portion between the heating cylinder head and the heating cylinder main body, a step is likely to occur at the joint portion. ,
Since the outer peripheral portion of the backflow prevention ring is caught by the joint step and hinders the smooth movement of the backflow prevention ring, and furthermore, there is a problem that the backflow prevention ring or the joint periphery is damaged. In order to avoid this, the tip of the backflow prevention ring is configured not to advance beyond the joint position even at the most advanced position during the pressure holding as described above.

[0005] However, depending on the tip structure of the conventional injection molding machine, the inner wall of the heating cylinder body expands due to wear over a long period of time, and resin is discharged from the joint surface between the heating cylinder head and the heating cylinder body. The problem of leakage to the outside occurs. Finally, when the filling pressure is applied by the screw, the molten resin flows backward between the inner wall of the heating cylinder and the screw, causing a so-called back flow. Conventionally,
In such a case, there is no alternative but to replace the heating cylinder main body, and there is a disadvantage that a large amount of cost is required.

On the other hand, in a thermosetting resin injection molding machine comprising an injection screw having a mixing mechanism for resin kneading, a heating cylinder main body, and an injection cylinder which can be divided into a cylinder head, the mixing mechanism for the injection screw is used. At the end of the part or behind said end,
Japanese Patent Application Laid-Open No. 52-25552 discloses an injection cylinder having an injection molding device provided with an inner joint surface formed at a connection portion between the head and the main body of the injection cylinder. Further, while following the basic technology of JP-A-52-42552, the outer peripheral portion of the backflow prevention ring is caught by a step at the inner periphery of the joint formed at the connection between the heating cylinder and the nozzle, and the smoothness of the backflow prevention ring is improved. Japanese Unexamined Patent Publication No. 9-24529 is known as a device which does not hinder a proper movement and does not damage the periphery of the joint portion of the backflow prevention ring or the nozzle. Here, the object of the invention according to Japanese Patent Application Laid-Open No. 52-25552 is that, when the nozzle is removed, the backflow prevention ring completely comes out of the heating cylinder, and during injection molding with a thermosetting resin, An object of the present invention is to enable unnecessary substances to be easily removed even when the resin material is cured in the heating cylinder.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks of the prior art. Also, according to the measurement results of the inner diameter of the heated cylinder actually worn by the inventor, as for the wear of the inner wall of the heated cylinder, the backflow prevention at the time of holding pressure where the resin filling pressure is most applied to the heated cylinder body. The inner wall portion corresponding to the most advanced position of the ring has the largest inner diameter expansion due to wear, and then the pellets put into the hopper are sent out toward the heating cylinder head and fixed by the first heater attached to the heating cylinder body. Since the inner wall portion of the heating cylinder corresponding to immediately below the first heater at which the shape of the pellet starts to soften was unexpectedly found to have the next highest wear, the present invention was also made based on this finding. is there. Accordingly, an object of the present invention is to reduce the construction cost by replacing only the heating cylinder head, even when the inner wall of the heating cylinder is worn due to long-term use and the heating cylinder must be replaced. It is an object of the present invention to provide a heating cylinder of an injection molding machine which can be easily replaced. It is still another object of the present invention to provide a heating cylinder of an injection molding machine that can remove unnecessary materials even when the resin material is cured in the heating cylinder during injection molding with a thermosetting resin.

[0008]

In order to achieve the above object, a heating cylinder of an injection molding machine according to the present invention can be divided into a screw having a backflow prevention ring at a tip, a heating cylinder main body and a heating cylinder head. A heating cylinder of an injection molding machine comprising a heating cylinder, wherein a ratio of a cylindrical inner diameter to a length in a joining direction of the heating cylinder head on the heating cylinder side is 1:10 to 1:20. A male screw groove is cut into a part of the outer wall of the long cylinder, and a female screw groove corresponding to the male screw groove is inserted and screwed in accordance with the long cylinder on the heating cylinder side of the heating cylinder body. The heating cylinder is cut into the inner wall of the receiving cylinder, and the heating cylinder inserts the long cylinder of the heating cylinder head into the receiving cylinder of the heating cylinder main body. The gist of the present invention is to screw an external thread groove.

In the heating cylinder of the injection molding machine according to the present invention, in addition to the gist described above, gas holes are formed in the long cylinder of the heating cylinder head through the inner wall side and the outer wall side of the long cylinder. Further, a gas discharge groove is formed from the outer wall side opening of the gas hole to the longitudinal end of the elongated cylinder in the longitudinal direction of the elongated cylinder, and continuously to the back surface of the flange portion of the heating cylinder head. A gas delivery hole may be formed so as to penetrate from the gas discharge groove on the back surface to the upper surface side of the flange portion.

[0010]

In the heating cylinder of the injection molding machine according to the present invention,
Even if the abrasion progresses with the increase in the frequency of use of the injection molding machine, the inner wall of the long cylinder of the heating cylinder head only expands due to the abrasion and the abrasion to the heating cylinder body does not occur. It works to maintain the performance of the cylinder.

[0011] Next, in the heating cylinder of the injection molding machine according to the present invention, as described above, a high pressure is applied as the molten resin is extruded and the holding pressure is applied, and it is estimated that the inner wall is most worn. A long cylinder of the heating cylinder head is formed even beyond the abraded inner wall portion immediately below the first heater at which the solid pellet starts to soften by the first heater attached to the heating cylinder body, and the first heater attached to the heating cylinder body. Because the pressure applied by the molten resin does not reach the joint surface between the heating cylinder head and the heating cylinder main body, even if the inner surface of the heating cylinder head expands due to wear due to the increase in usage frequency, conventional injection molding This prevents the resin from leaking to the outside from the joint surface between the heating cylinder head and the heating cylinder main body as in the case of the heating cylinder of the machine.

Next, in the heating cylinder of the injection molding machine according to the present invention, Japanese Patent Application Laid-Open No. 52-42 described in the prior art section.
As for the problem to be solved by the invention according to No. 552, when the screw between the heating cylinder main body and the heating cylinder head is unscrewed and the long cylinder of the heating cylinder head is removed from the receiving cylinder of the heating cylinder main body, the screw is heated. Since it appears in a projecting state with a predetermined gap from the inner surface of the receiving cylinder of the cylinder main body, it acts so that unnecessary materials can be removed even when the resin material is cured in the heating cylinder during injection molding with a thermosetting resin. .

Further, in the heating cylinder of the injection molding machine according to the present invention, the heating is performed beyond the inner bottom portion of the heating cylinder head which is heavily worn as described above, and also the inner wall immediately below the first heater which is abraded second. Since the long cylinder of the cylinder head is configured and the backflow prevention ring of the screw that advances and retreats during the injection molding process is configured to advance and retreat along the inner wall of the long cylinder, the reciprocation path of the backflow prevention ring Since there is no step above due to the joint surface between the heating cylinder main body and the heating cylinder head, the above-mentioned backflow prevention ring acts so that it can move smoothly.

Further, in the heating cylinder of the injection molding machine according to the present invention, the heating cylinder head has gas holes, gas discharge grooves,
Since the gas delivery hole is provided, the gas generated in the heating cylinder due to the melting of the filling resin can be discharged outside the machine,
It works so that troubles such as molding failure caused by the gas can be solved.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail through preferred embodiments of the present invention with reference to the drawings.

First, FIG. 5 is a schematic view mainly showing the tip of a conventional general injection molding machine. As shown, a heating cylinder 100 of an injection molding machine generally includes a heating cylinder main body 101.
The heating cylinder head 102 and the heating cylinder head 10
2 is provided with a nozzle 103 at the tip. Here, the heating cylinder main body 101 is a substantially cylindrical body, and a screw 107 composed of a screw spire 104, a backflow prevention ring 105, and a screw main body 106 is disposed in the substantially cylindrical body. The screw 107 advances and retreats along the inner wall of the heating cylinder main body 101 in accordance with a molding process of an injection molding machine such as resin measurement and injection filling. On the other hand, as shown in FIG.
08 is provided with three heaters 109, and the resin pellets input from the hopper 110
When the resin is extruded toward the heating cylinder head 102 by 07, it is melted by the heater 109.
Here, a male screw groove is cut on the outer wall of the annular bulging portion at a joint portion of the heating cylinder head 102 on the heating cylinder side, and a female screw groove corresponding to the male screw groove is formed on the heating cylinder main body 1.
01 is cut into the inner wall of the depressed concave portion at the front end, and the heating cylinder 100 is screwed with the male thread groove of the heating cylinder head 102 into the female thread groove formed at the tip of the heating cylinder main body 101, and The flange portion 111 of the head 102 and the bolt hole 112 formed in the distal end portion of the heating cylinder main body are aligned and bolted to join the two. In the heating cylinder 100 configured as described above, as the frequency of use increases, wear on the heating cylinder main body 101 progresses, and finally, the filled resin flows back to the screw 107 side, so-called backflow occurs. Become.

Next, the results of measurement and investigation by the present inventor on the state of wear of the inner wall of the heating cylinder main body 101 will be described. Each of the heating cylinder bodies subjected to the measurement investigation was used for injection molding for more than three years. However, in recent years, in resin products, it has become mainstream to use hard materials such as glass fibers and carbon fibers as fillers for the purpose of improving mechanical strength, heat resistance and flame retardancy. Is said to have increased wear and reduced service life. First, as a first example, when a measurement was carried out on a heating cylinder main body having an inner diameter of 22 mm and a length of 676 mm, the wear was expanded up to a diameter of 0.27 mm at a position 20 mm from the inner wall tip of the heating cylinder main body, Then, it was expanded by 0.23 mm in a straight line at a position of 360 mm from the tip of the inner wall. Subsequently, as a second example, when measuring a heating cylinder main body having an inner diameter of 22 mm and a length of 560 mm, the wear at the position of 20 mm and 30 mm from the tip of the inner wall of the heating cylinder main body had a maximum straight diameter of 0.68 mm, Then, go straight through 0.3 at 280 mm from the tip of the inner wall.
It was a 7mm expansion. As a third example, the measurement was performed on a heating cylinder main body having an inner diameter of 22 mm and a length of 615 mm. In this case, the result was that the wear was straight at 0.16 mm at a position 20 mm from the tip of the inner wall of the heating cylinder main body, and the maximum wear was 0.42 mm at a position 200 mm from the tip of the inner wall.

From the above results, the state of wear on the inner wall of the heating cylinder main body became clear, and the wear position was examined.
The position 20 mm from the tip of the inner wall of 1 is the stop position of the backflow prevention ring 105 when the screw spire 104 comes into contact with the substantially funnel-shaped bottom surface of the heating cylinder head 102 and the holding pressure is performed. Although the length of the heating cylinder main body and the length of the screw differ depending on the manufacturer, the stop position of the backflow prevention ring 105 is the same as long as the inner diameter is the same. Next, with respect to the abrasion at the slightly rearward position of the inner wall of the heating cylinder main body, it was found that any of these abuts directly below the first heater attached to the outer periphery of the heating cylinder main body. Although the detailed reason for the wear is unknown, this position corresponds to a position where the resin pellets supplied from the hopper 110 start softening. The present invention has been created based on the above findings.

FIG. 1 is a schematic diagram mainly showing the tip of the injection molding machine according to the present invention. As shown in the figure, a heating cylinder 1 of an injection molding machine according to the present invention comprises a heating cylinder main body 2, a heating cylinder head 3 loaded from the distal end of the heating cylinder main body 2, and a nozzle 4 at the distal end of the heating cylinder head 3. Is provided. Here, the heating cylinder main body 2 is a substantially cylindrical body, and the screw spire 5, the backflow prevention ring 6,
A screw 8 composed of a screw body 7 is arranged. On the other hand, a triple heater 10 with a thermocouple 9 is provided on the outer periphery of the heating cylinder main body 2 as shown in the figure, and resin pellets supplied from a hopper 11 are extruded toward the heating cylinder head 3 by a screw 8. When the heater 10 is melted, it is melted by the heater 10. Here, the joining portion of the heating cylinder head 3 on the heating cylinder main body side is a long cylinder 12. Further, a male screw groove 13 is cut at the end of the outer wall of the long cylinder 12, while the long cylinder 1 of the heating cylinder main body 2 is cut.
A female screw groove 15 corresponding to the male screw groove 13 is cut in the bottom of the inner wall of the receiving cylinder 14 into which the screw 2 is inserted and screwed. In the heating cylinder 1, the long cylinder 12 of the heating cylinder head 3 is inserted into the receiving cylinder 14 of the heating cylinder main body 2, and the male thread groove 13 of the heating cylinder head 3 is screwed into the female thread groove 15 of the heating cylinder main body 2. Things. Further, in the long cylinder 12, the ratio of the cylindrical inner diameter to the length in the joining direction is about 1:16. As a result, as shown in the figure, the tip of the long cylinder 12 is positioned directly below the first heater 10. The hopper 11 reaches a position just before the resin pellet supply port 16 of the hopper 11 further extended.
Then, the flange portion 17 of the heating cylinder head 3 and the bolt hole 18 formed in the distal end portion of the heating cylinder main body are aligned and bolted to join the two.

Further, FIG. 2 is a sectional view of the heating cylinder main body according to the present invention, FIG. 3 is a sectional view of the heating cylinder head according to the present invention, and FIG. 4 is a right side view in the direction of FIG.
Here, FIG. 2 is a sectional view showing a state where the heating cylinder head 3 is removed from the heating cylinder 1 according to the present invention. As shown, the screw 8 has a gap with the inner surface of the receiving cylinder 14 of the heating cylinder main body 2. Since it appears in a protruding state, unnecessary substances can be removed even when the resin material is cured in the heating cylinder during injection molding with a thermosetting resin. In this case, it is preferable that the screw 8 be advanced in the opening direction of the receiving cylinder 14. On the other hand, as shown in FIGS. 3 and 4, a gas hole 19 is formed in the long cylinder 12 of the heating cylinder head 3 so as to penetrate the inner wall side and the outer wall side. A gas discharge groove 20 is formed in the longitudinal direction of the long cylinder 12 in the longitudinal direction of the long cylinder 12 and continuously over the back surface of the flange portion 17 of the heating cylinder head 3.
0 to the flange 17 at the top side of the gas delivery hole 21
Are drilled. Thereby, the gas generated in the heating cylinder 1 due to the melting of the filling resin can be discharged outside the machine.

[0021]

Since the present invention is configured as described above in detail, it has the following effects.

In the heating cylinder of the injection molding machine according to the present invention, as described above, a high pressure is applied along with the extrusion and holding pressure of the molten resin, and the inner bottom portion of the heating cylinder head which is estimated to have the greatest wear on the inner wall is provided. Further, the heating cylinder is moved to a position where the pressure of the molten resin does not reach beyond the inner wall portion directly below the first heater where the solid pellet starts to be softened by the first heater attached to the heating cylinder main body. Even if the inner surface of the heating cylinder head expands due to wear due to the increase in the frequency of use, the heating cylinder head can be replaced, and the heating cylinder head can be replaced, and heating can be performed at low cost and simple replacement work. There is an effect that the tube can be regenerated.

Further, in the heating cylinder of the injection molding machine according to the present invention, since the heating cylinder head is formed in a long cylindrical shape, the inner surface of the heating cylinder head expands due to wear as the frequency of use increases. However, there is also an effect that the resin does not leak out from the joint surface between the heating cylinder head and the heating cylinder main body, unlike the heating cylinder of the conventional injection molding machine.

Further, in the heating cylinder of the injection molding machine according to the present invention, when the long cylinder of the heating cylinder head is removed from the cylinder of the heating cylinder main body, the screw is fixed to the inner surface of the cylinder of the heating cylinder main body by a predetermined clearance. Therefore, even when the resin material is cured in the heating cylinder during the injection molding using the thermosetting resin, there is an effect that unnecessary substances can be removed.

Subsequently, in the heating cylinder of the injection molding machine according to the present invention, as described above, the heating cylinder head also has the inner bottom of the heating cylinder head which is heavily worn, and the inner wall immediately below the first heater which is also heavily worn. Since the long cylinder of the heating cylinder head is configured and the backflow prevention ring of the screw that advances and retreats during the injection molding process is configured to advance and retreat along the inner wall of the long cylinder, the backflow prevention ring advances and retreats. Since there is no step on the track due to the joining surface between the heating cylinder main body and the heating cylinder head, there is also an effect that the backflow prevention ring can move smoothly.

Furthermore, in the heating cylinder of the injection molding machine according to the present invention, since the heating cylinder head is provided with a gas hole, a gas discharge groove, and a gas delivery hole, the gas is generated in the heating cylinder as the filling resin is melted. Since the gas can be discharged out of the apparatus, there is also an effect that there is no molding defect due to the gas and the product accuracy can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram mainly showing a front end portion of an injection molding machine according to the present invention.

FIG. 2 is a sectional view of a heating cylinder main body according to the present invention.

FIG. 3 is a sectional view of a heating cylinder head according to the present invention.

FIG. 4 is a right side view in the direction of FIG. 3;

FIG. 5 is a schematic view mainly showing a tip portion of a conventional general injection molding machine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 100 Heating cylinder 2, 101 Heating cylinder main body 3, 102 Heating cylinder head 4, 103 Nozzle 5, 104 Screw spire 6, 105 Backflow prevention ring 7, 106 Screw main body 8, 107 Screw 9, 108 Thermocouple 10, 109 Heater 11, 110 Hopper 12 Long cylinder 13 Male thread groove 14 Receiving cylinder 15 Female thread groove 16 Resin pellet supply port 17, 111 Flange part 18, 112 Bolt hole 19 Gas hole 20 Gas discharge groove 21 Gas delivery hole

Claims (2)

[Claims] 1. A heating cylinder for an injection molding machine, comprising: a screw having a backflow prevention ring at a tip end; and a heating cylinder which can be divided into a heating cylinder main body and a heating cylinder head, wherein the heating cylinder of the heating cylinder head is provided. The joint portion on the side is a long cylinder having a ratio of the cylindrical inner diameter to the length in the joining direction of 1:10 to 1:20, and a male screw groove is cut into a part of the outer wall of the long cylinder, A female thread groove corresponding to the male thread groove is cut into the inner wall of a receiving cylinder into which the long cylinder on the heating cylinder side of the heating cylinder body is inserted and screwed in response to the male screw groove, and the heating cylinder is the heating cylinder body. A heating cylinder for an injection molding machine, characterized in that the long cylinder of the heating cylinder head is inserted into the receiving cylinder, and the male thread groove of the heating cylinder head is screwed into the female thread groove of the heating cylinder body. 2. A gas cylinder is formed in the long cylinder of the heating cylinder head so as to penetrate through the inner wall side and the outer wall side of the long cylinder. A gas discharge groove is formed on the base end of the long cylinder and continuously on the back surface of the flange portion of the heating cylinder head. Subsequently, a gas delivery hole is formed through the gas discharge groove on the back surface of the flange portion to the upper surface side of the flange portion. The heating cylinder of an injection molding machine according to claim 1, wherein the heating cylinder is provided.