Screw for injection molding apparatus, and injection molding apparatus

Abstract

To provide a screw for an injection molding apparatus and an injection molding apparatus that favorably perform desired molding.SOLUTION: A screw 30 for an injection molding apparatus is used in the injection molding apparatus. The screw 30 has: a shaft 31 extending from a feed part to a measuring part; a groove 32 continuously and spirally formed on the shaft 31; and a rib-shaped flight 33 formed between adjacent grooves 32 in an extension direction of the shaft 31. In the screw 30, a width of the flight 33 in the feed part is wider than a width of the flight 33 in the measuring part. A pitch of the flight 33 in the feed part is smaller than a pitch of the flight 33 in the measuring part. A depth of the groove 32 in the feed part is deeper than a depth of the groove 32 in the measuring part.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a screw for an injection molding apparatus and an injection molding apparatus. [Background technology]

[0002] In an in-line screw type injection molding apparatus, various proposals have been disclosed regarding the shape of the screw.

[0003] For example, an injection molding device has been disclosed that has a screw that is composed of a first region in which the flight pitch, groove width, and groove depth are constant, and a second region in which the flight pitch is constant, the groove depth becomes gradually shallower, and the groove width becomes larger (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-224801 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the above-mentioned technology, the flight pitch at the tip is determined by the screw shape in the region that receives the raw resin, and therefore, when high pressure is applied to the resin at the tip of the screw, it is difficult to control the backflow of the resin due to this pressure in a well-balanced manner.

[0006] The present disclosure has been made to solve such problems, and has an object to provide a screw for an injection molding device that can suitably perform a desired molding. [Means for solving the problem]

[0007] The screw for injection molding apparatus according to the present disclosure is a screw for use in an injection molding apparatus that receives raw material in a supply section on the upstream side, transports the raw material to a metering section while heating it, and injects the molten raw material into a mold provided on the downstream side of the metering section. The screw for injection molding apparatus has a shaft extending from the supply section to the metering section, a groove formed in a spiral shape continuously on the shaft, and a rib-like flight formed between adjacent grooves in the extension direction of the shaft. In addition, the width of the flight in the supply section of this screw is wider than the width of the flight in the metering section, the pitch of the flight in the supply section is smaller than the pitch of the flight in the metering section, and the depth of the groove in the supply section is deeper than the depth of the groove in the metering section.

[0008] The injection molding apparatus according to the present disclosure includes a heating cylinder and a screw housed in the heating cylinder so as to be rotatable and movable forward and backward. The injection molding apparatus kneads and plasticizes the raw material received in the supply section by rotating the screw, and injects the plasticized raw material from the metering section toward a mold by moving the screw forward and backward. The screw has a shaft extending from the supply section to the metering section, a groove formed in a spiral shape continuously on the shaft, and a rib-like flight formed between adjacent grooves in the extension direction of the shaft. The screw has a width of the flight in the supply section wider than the width of the flight in the metering section, a pitch of the flight in the supply section smaller than the pitch of the flight in the metering section, and a depth of the groove in the supply section deeper than the depth of the groove in the metering section. Effect of the Invention

[0009] According to the present disclosure, it is possible to provide a screw for an injection molding apparatus and an injection molding apparatus that suitably performs a desired molding. [Brief description of the drawings]

[0010] [Figure 1] 1 is an overall configuration diagram of an injection molding apparatus according to an embodiment; [Diagram 2] FIG. 2 is a partially enlarged view of a screw according to an embodiment. [Diagram 3]FIG. 2 is an external view for explaining the shape of a screw. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present invention will be described below through the embodiments of the invention, but the invention according to the claims is not limited to the following embodiments. In addition, not all of the configurations described in the embodiments are necessarily essential as means for solving the problems. For clarity of explanation, the following description and drawings are omitted and simplified as appropriate. In each drawing, the same elements are given the same reference numerals, and duplicate explanations are omitted as necessary.

[0012] <Embodiment Mode> Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is an overall configuration diagram of an injection molding apparatus 1 according to the embodiment. Note that the injection molding apparatus 1 shown in Fig. 1 is partially shown in cross section for easy understanding.

[0013] For convenience in explaining the positional relationships of the components, FIG. 1 is illustrated with a right-handed Cartesian coordinate system. The positive Z-axis direction coincides with the vertical upward direction. The XY plane coincides with the horizontal plane. Furthermore, in FIG. 2 and subsequent figures, when a Cartesian coordinate system is illustrated, the X-axis, Y-axis, and Z-axis directions in FIG. 1 coincide with the X-axis, Y-axis, and Z-axis directions of these Cartesian coordinate systems, respectively.

[0014] The injection molding apparatus 1 is used, for example, as one component of a molding system for manufacturing a desired molded product from a raw material. The raw material is, for example, a resin. The resin may contain additives such as fibers or beads. The raw material may also be, for example, a metal powder other than resin.

[0015] The injection molding apparatus 1 is fixed on a base 3 together with the mold clamping device 2, and is controlled to cooperate with the mold clamping device 2. The injection molding apparatus 1 is connected to the mold clamping device 2 so as to be able to supply plasticized raw material. Note that plasticization can also be said to mean melting the raw material. The mold clamping device 2 holds a mold 90. The injection molding apparatus 1 receives pellet-shaped raw material, plasticizes the received raw material, and injects it into the mold 90. The injection molding apparatus 1 mainly includes a cylinder 10, a hopper 20, a screw 30, a heater 40, a nozzle 50, and a drive block 60.

[0016] The cylinder 10 is a cylindrical member extending horizontally (in the X-axis direction). The cylinder 10 is connected to a hopper 20 on the upstream side (positive side of the X-axis) and receives raw material from the hopper 20. The hopper 20 receives and stores the raw material, and supplies the stored raw material to the cylinder 10 as appropriate. The cylinder 10 may be referred to as a heating cylinder.

[0017] The cylinder 10 also accommodates therein the screw 30 so that it can rotate and move forward and backward. The cylinder 10 is connected to a drive block 60 further upstream than the portion to which the hopper 20 is connected. The drive block 60 includes a drive device for rotating and moving the screw 30 forward and backward. By rotating, the screw 30 conveys the raw materials received via the hopper 20 downstream (the negative side of the X-axis) while kneading them.

[0018] The downstream tip of the cylinder 10 (the end on the negative X-axis side) becomes gradually thinner, and a nozzle 50 is formed. The nozzle 50 is set so as to be able to inject the raw material conveyed to the tip by the screw 30. The nozzle 50 is fitted into a recess provided in a fixed platen of the mold clamping device 2. The screw 30 is driven by a drive block 60 to move from the upstream side to the downstream side. In this way, the injection molding device 1 pushes out the raw material stored at the tip of the cylinder 10 from the nozzle 50 into the mold 90.

[0019] The screw 30 is housed so as to be rotatable and movable forward and backward along the extension direction of the cylinder 10. The rotational movement of the screw 30 here is a movement of rotating in the extension direction of the cylinder 10 (around the Y-axis). The forward and backward movement of the screw 30 here is a movement from upstream to downstream (the negative side of the X-axis) and a movement from downstream to upstream (the positive side of the X-axis).

[0020] The screw 30 is connected to the drive block 60 on the upstream side, and rotates and moves forward and backward according to a drive device of the drive block 60. The screw 30 rotates to transport the raw material received through the hopper 20 to the downstream side. The screw 30 also plasticizes the raw material while transporting it.

[0021] Furthermore, as the screw 30 moves downstream, it pushes out the raw material transported downstream of the cylinder 10 from the nozzle 50 to the outside of the injection molding apparatus 1. After the raw material is pushed out, the screw 30 moves upstream while rotating to transport the raw material downstream. As a result, the screw 30 stores the plasticized raw material again downstream of the cylinder 10.

[0022] In order to realize the above-mentioned functions, the screw 30 can be divided into a supply section A1, a compression section A2, and a metering section A3 from the upstream side along the stretching direction. That is, the screw 30 receives raw material in the supply section A1 and conveys the received raw material downstream. In the compression section A2, the screw 30 compresses the raw material received from the supply section A1 to plasticize it, while conveying it to the downstream metering section A3. In the metering section A3, the screw 30 conveys the plasticized raw material downstream of the metering section A3.

[0023] The screw 30 further has a screw head portion A4 downstream of the metering portion A3. The screw head portion A4 includes a head 34 and a ring 35. The head 34 is a cone-shaped member provided at the tip of the screw 30. The head 34 approaches the nozzle 50 when the screw 30 injects the raw material. This causes the raw material stored downstream of the head 34 to be pushed out from the nozzle 50 toward the die 90. The ring 35 is an annular member for suppressing backflow of the plasticized raw material in the region provided between the head 34 and the metering portion.

[0024] The heater 40 is a heating device provided on the outer periphery of the cylinder 10 along the extension direction of the cylinder 10. The heater 40 is, for example, a sheath heater or a ceramic heater. The heater 40 may use a heating medium such as oil. The heater 40 may be divided into a plurality of segments along the extension direction of the cylinder 10. In this case, the heater 40 is structured such that the heating temperature can be set for each segment. The heater 40 may be configured to be able to heat the nozzle 50 portion as well.

[0025] The drive block 60 is connected to the screw 30, and drives the screw 30 to rotate and linearly drive the screw 30. To this end, the drive block 60 has a motor for rotating the screw 30 and a motor for moving the screw 30 forward and backward.

[0026] Next, the configuration of the screw 30 will be further described with reference to Fig. 2. Fig. 2 is a partially enlarged view of the screw 30 according to the embodiment. The screw 30 shown in Fig. 2 is partially shown in cross section for ease of understanding. The screw 30 has, as its main components, a shaft 31, a groove 32, a flight 33, and a head 34. The screw 30 also has a ring 35 adjacent to the head 34.

[0027] The shaft 31 extends from the supply section to the metering section. The diameter C of the shaft 31 is set so that the shaft 31 operates without significant rattling relative to the inner diameter of the cylinder 10. The shaft 31 is formed with a continuous spiral groove 32. The flight 33 is a rib-like portion formed between adjacent grooves 32 in the extension direction of the shaft 31.

[0028] Here, the depth D of the groove 32 is the depth from the outer diameter surface of the shaft 31 to the bottom surface of the groove 32. Moreover, the width B of the flight 33 is the length of a portion corresponding to the outer diameter surface of the shaft 31 in a cross section passing through the center line of the shaft 31. The width B of the flight 33 can also be said to be the length of the top of the flight 33 in the extension direction of the screw 30. Moreover, the pitch P of the flights 33 is the pitch of adjacent flights 33 in the extension direction of the screw 30. The pitch of the flights 33 can also be said to be the pitch of the groove 32. The depth D of the groove 32, the width B of the flight 33, and the pitch P of the flight 33 each have different dimensions depending on the position on the screw 30.

[0029] In addition, the angle F between the flight 33 from the supply section to the metering section of the screw 30 in this embodiment and a cross section perpendicular to the screw axis (a cross section perpendicular to the central axis of the screw 30) is set within the range of 16 degrees to 26 degrees.

[0030] Next, specific features of the shape of each part of the screw 30 will be described with reference to Fig. 3. Fig. 3 is an external view for explaining the shape of the screw. The screw 30 shown in Fig. 3 is a part housed in the cylinder 10. The screw 30 is connected to a drive block 60 on the positive side of the X-axis in Fig. 3. However, Fig. 3 does not show the connection part with the drive block 60.

[0031] The symbols indicating the depth, flight width, and flight pitch of the groove 32 of the screw 30 shown in Fig. 3 are followed by numbers after the symbols shown in Fig. 2. This is to indicate that the dimensions of each part differ depending on the position, and therefore each position has different dimensions. For example, the groove 32 in the supply section A1 has a depth D1, and the groove 32 in the metering section A1 has a depth D3.

[0032] In light of the above, the shape of the screw 30 shown in Fig. 3 will be described. In the screw 30, the width B1 of the flight 33 in the supply section A1 is wider than the width B3 of the flight in the metering section A3. In other words, the width B3 of the flight 33 in the metering section A3 is narrower than the width B1 of the flight in the supply section A1.

[0033] More specifically, the width B3 of the flight 33 in the metering section A3 is 27 percent to 60 percent of the width B1 of the flight 33 in the supply section A1.

[0034] Furthermore, the pitch P1 of the flights 33 in the supply section A1 is smaller than the pitch P3 of the flights 33 in the metering section A3.

[0035] More specifically, the pitch P3 of the flights 33 in the metering section A3 is 110 percent to 170 percent of the pitch P1 of the flights 33 in the supply section A1.

[0036] The depth D1 of the groove 32 in the supply section A1 is greater than the depth D3 of the groove 32 in the metering section A3.

[0037] Alternatively, the cross-sectional area (D1×(P1−B1)) parallel to the extension direction of groove 32 in supply section A1 is 100 to 150 percent of the cross-sectional area (D3×(P3−B3)) of groove 32 in metering section A3.

[0038] Moreover, the groove 32 of the screw 30 is formed in the compression section A2 so as to become gradually shallower from the supply section A1 toward the metering section A3. That is, in the compression section A2 shown in Fig. 3, the depth D22 of the groove 32 on the side relatively closer to the metering section A3 is shallower than the depth D21 of the groove 32 on the side relatively closer to the supply section A1.

[0039] The flight 33 is formed so that the width gradually narrows from the upstream side to the downstream side in the compression portion A2. That is, for example, the downstream width B22 in the compression portion A2 is narrower than the upstream width B21.

[0040] The flights are formed such that the pitch gradually increases from the upstream side to the downstream side in the compression section, i.e., for example, the pitch P22 on the downstream side in the compression section A2 is wider than the pitch P21 on the upstream side.

[0041] The above describes the screw 30. As described above, the width B and pitch P of the flights 33 in the screw 30 change along the stretching direction. Furthermore, the depth D of the grooves 32 in the screw 30 can also change along the stretching direction. Therefore, the shape and cross-sectional area of ​​the grooves 32 in the screw 30 are set by three parameters, the width B of the flights 33, the pitch P, and the depth D of the grooves 32.

[0042] However, if the width B of the flight 33 is kept constant and the pitch P is increased from the upstream side to the downstream side, the lead angle of the flight 33 in the metering section A3 becomes relatively large compared to the above-mentioned screw 30. When the raw material is supplied downstream of the metering section A3 in the injection molding apparatus 1 using a screw with a constant flight width, the raw material tends to flow back into the metering section A3.

[0043] On the other hand, when the pitch P of the flight 33 is kept constant and the width B is narrowed from the upstream side to the downstream side, the compression ratio (S1 / S2), which is the ratio between the cross-sectional area S1 of the groove 32 in the supply section A1 and the cross-sectional area S2 of the groove 32 in the metering section A3, becomes higher than that of the above-mentioned screw 30. In other words, in a screw with a constant flight pitch, the shear heat is likely to increase due to the high compression ratio, and as a result, the raw material is likely to deteriorate.

[0044] The screw 30 according to the present disclosure, compared to the above-mentioned screw with a fixed flight width, can increase the cross-sectional area of ​​the groove 32 while suppressing an increase in the pitch P of the flight 33 in the metering section A3. Therefore, the screw 30 can suppress backflow of the raw material when the pressure of the raw material increases in the region from the metering section A3 to the head section A4. Alternatively, the screw 30 can suppress a decrease in the flow rate of the raw material conveyed to the tip side of the screw when the pressure of the raw material increases in the region from the metering section A3 to the head section A4 of the screw.

[0045] Furthermore, the screw 30 can keep the compression ratio low compared to the above-mentioned screw with a fixed flight pitch. Therefore, the screw 30 can suppress the deterioration of the raw material. Furthermore, by performing molding at a relatively low compression ratio, the screw 30 can suppress quality deterioration such as wear and breakage of the flights.

[0046] As described above, according to the embodiments, it is possible to provide a screw for an injection molding apparatus and an injection molding apparatus that can suitably perform a desired molding.

[0047] Although the present invention has been described above with reference to the embodiment, the present invention is not limited to the above. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the invention. [Explanation of symbols]

[0048] 1 Injection molding equipment 2 Mold clamping device 3. Foundation 10 Cylinders 20 Hopper 30 Screw 31 Axis 32 Groove 33 flights 34 Head 35 Ring 40 Heater 50 nozzles 60 Drive Block 90 Mold

Claims

1. A screw for use in an injection molding device that receives a raw material in a supply section on the upstream side, conveys the raw material to a metering section while heating it, and injects the molten raw material into a mold provided downstream of the metering section, A shaft extending from the supply section to the metering section; a groove formed continuously and spirally on the shaft; a rib-like flight formed between adjacent grooves in the extension direction of the axis; Equipped with the width of the flight in the supply section is wider than the width of the flight in the metering section; the pitch of the flight in the supply section is smaller than the pitch of the flight in the metering section; The depth of the groove in the supply section is greater than the depth of the groove in the measuring section. Screw for injection molding equipment.

2. the width of the flight at the metering section is 40 percent of the width of the flight at the supply section; The screw for an injection molding apparatus according to claim 1.

3. the pitch of the flights of the metering section is 140 percent of the pitch of the flights of the feed section; The screw for an injection molding apparatus according to claim 1.

4. A cross-sectional area of ​​the groove in the supply section parallel to the extension direction is 100 to 150 percent of a cross-sectional area of ​​the groove in the metering section. The screw for an injection molding apparatus according to any one of claims 1 to 3.

5. A compression section is provided between the supply section and the metering section, The groove is formed in the compression section so as to become gradually shallower from the supply section toward the metering section. The screw for an injection molding apparatus according to claim 1.

6. The flight is formed so that the width gradually narrows from the upstream side to the downstream side in the compression portion. The screw for use in an injection molding apparatus according to claim 5.

7. The flight is formed such that the pitch gradually becomes wider from the upstream side to the downstream side in the compression portion. The screw for an injection molding apparatus according to claim 5 or 6.

8. The angle between the flight and the cross section perpendicular to the screw axis from the supply section to the metering section is set within the range of 16 degrees to 26 degrees. The screw for use in an injection molding apparatus according to claim 7.

9. An injection molding apparatus having a heating cylinder and a screw rotatably and retractably housed within the heating cylinder, kneading and plasticizing a raw material received in a supply section by rotating the screw, and injecting the plasticized raw material from a metering section into a mold by moving the screw forward and backward, The screw is A shaft extending from the supply section to the metering section; a groove formed continuously and spirally on the shaft; a rib-like flight formed between adjacent grooves in the extension direction of the axis; Equipped with the width of the flight in the supply section is wider than the width of the flight in the metering section; the pitch of the flight in the supply section is smaller than the pitch of the flight in the metering section; The depth of the groove in the supply section is greater than the depth of the groove in the measuring section. Injection molding equipment.

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