Injection molding machine

Abstract

The present invention provides an injection molding device capable of supplying molding material from multiple hoppers in appropriate proportions. [Solution] An injection molding device for injecting molding material into the cavity of a clamped mold comprises a heating cylinder filled with molding material, a first hopper for supplying molding material to the heating cylinder, a second hopper for supplying molding material to the tip side of the heating cylinder from the first hopper, and a screw having a helical groove formed on its outer circumference, which rotates and retracts inside the heating cylinder to measure the molding material, and advances inside the heating cylinder to inject the molding material into the cavity. The screw has a first part facing the first hopper and a second part facing the second hopper, the volume per unit length of the helical groove being larger than that of the first part.

Description

Technical Field

[0001] The present invention relates to an injection device and a molding machine capable of mixing and injecting a plurality of types of molding materials.

Background Art

[0002] Conventionally, an injection device for injecting a molding material into a cavity of a clamped mold includes a heating cylinder filled with the molding material, a hopper for supplying the molding material to the heating cylinder, and a screw that rotates inside the heating cylinder while retreating to measure the molding material and advances inside the heating cylinder to inject the molding material into the cavity.

[0003] In addition, in order to mix and inject a plurality of types of molding materials in a heating cylinder, an injection device provided with hoppers at a plurality of positions spaced apart in the extending direction of the heating cylinder is known (see, for example, Patent Documents 1 to 3).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the injection device having the above configuration, the molding material supplied from the rear hopper moves forward along the spiral groove as the screw rotates and retreats. Therefore, there is a problem that the spiral groove facing the front hopper is already filled with the molding material, and it is difficult to supply the molding material from the front hopper to the heating cylinder.

[0006] The present invention has been made in view of the above circumstances, and its object is to provide an injection molding device capable of supplying molding material from multiple hoppers in appropriate proportions. [Means for solving the problem]

[0007] To solve the above problems, the present invention provides an injection molding device for injecting a molding material into the cavity of a clamped mold, comprising: a heating cylinder filled with molding material; a first hopper for supplying molding material to the heating cylinder; a second hopper for supplying molding material to the tip side of the heating cylinder from the first hopper; and a screw having a helical groove formed on its outer circumference, which rotates and retracts inside the heating cylinder to measure the molding material, and advances inside the heating cylinder to inject the molding material into the cavity, wherein the screw has a first portion facing the first hopper and a second portion facing the second hopper, the volume per unit length of the helical groove being larger than that of the first portion. [Effects of the Invention]

[0008] According to the present invention, an injection molding apparatus capable of supplying molding material from multiple hoppers in appropriate proportions can be obtained. [Brief explanation of the drawing]

[0009] [Figure 1] This is a side view of the injection molding machine according to this embodiment. [Figure 2] This is an exploded view of the heating cylinder, screw, first hopper, and second hopper. [Figure 3] This diagram shows the relative positions of the heating cylinder, screw, first hopper, and second hopper. [Figure 4] This diagram shows variations of hoppers. [Figure 5] This figure shows the shape of a screw in a modified form. [Modes for carrying out the invention]

[0010] The injection molding machine 10 according to the present invention will be described below with reference to the drawings. The injection molding machine 10 is a device that injects a measured amount of plasticizer resin (molding material) into a mold to form a molded product. However, the specific example of a molding machine is not limited to the injection molding machine 10, and a die-casting machine that injects molten metal (molding material) into a mold to form a molded product may also be used.

[0011] [Configuration of injection molding machine 10] Figure 1 is a side view of the injection molding machine 10 according to this embodiment. As shown in Figure 1, the injection molding machine 10 mainly comprises a mold clamping device 20 and an injection device 30.

[0012] The mold clamping device 20 opens and closes the mold 21 and clamps it. Specifically, the mold clamping device 20 mainly comprises a fixed die plate 23 that supports the fixed side mold 22 and a movable die plate 25 that supports the movable side mold 24. The fixed side mold 22 and the movable side mold 24 are supported so as to face each other in the left-right direction (horizontal direction) of the injection molding machine 10.

[0013] The movable die plate 25 moves left and right along the tie bar 27 as the driving force of the mold opening / closing motor (not shown) is transmitted through the toggle link mechanism 26. When the movable die plate 25 moves to the left, the fixed mold 22 and the movable mold 24 separate. On the other hand, when the movable die plate 25 moves to the right, the fixed mold 22 and the movable mold 24 come into contact, forming a cavity (internal space) inside the mold 21. When further pressure is applied in the direction that moves the movable die plate 25 to the right, the fixed mold 22 and the movable mold 24 are clamped together.

[0014] The injection device 30 plasticizes, measures, and injects the molding material. In this embodiment, the injection device 30 is positioned opposite the clamping device 20 in the horizontal direction (to the right of the clamping device 20). The injection device 30 mainly comprises a heating cylinder 31, a screw 32, a first hopper 33, and a second hopper 34.

[0015] The heating cylinder 31 is a cylindrical member that extends linearly in the left - right direction of the injection molding machine 10. The heating cylinder 31 mainly includes a resin passage 35 and a nozzle 36. Also, a band heater (not shown) for heating the heating cylinder 31 is attached to the outer peripheral surface of the heating cylinder 31.

[0016] The resin passage 35 is a cylindrical space that extends in the axial direction (longitudinal direction) inside the heating cylinder 31. The resin passage 35 communicates with the outside of the heating cylinder 31 (the cavity of the mold 21) through a nozzle 36 provided at the tip (front end) of the heating cylinder 31. In other words, the resin passage 35 is a space that extends axially from the nozzle 36.

[0017] The screw 32 is a generally cylindrical member. On the outer peripheral surface of the screw 32, a groove (hereinafter referred to as "spiral groove 43") that extends spirally along the longitudinal direction of the screw 32 is formed. The screw 32 is accommodated in the internal space of the heating cylinder 31 in a state where it can move (hereinafter referred to as "advance and retreat") and rotate in the left - right direction of the injection molding machine 10. Also, the screw 32 in the heating cylinder 31 is configured to be replaceable. In other words, screws 32 with different specifications (for example, material, shape of the spiral groove 43, volume of the spiral groove 43) can be inserted into the heating cylinder 31.

[0018] The driving force of an injection motor (not shown) is transmitted to the screw 32 to cause it to advance and retreat, and the driving force of a metering motor (not shown) is transmitted to the screw 32 to cause it to rotate. More specifically, when the injection motor is rotated forward, the screw 32 moves (advances) toward the tip (i.e., the nozzle 36) of the heating cylinder 31. On the other hand, when the injection motor is rotated in reverse, the screw 32 moves (retreats) toward the base end (i.e., the side opposite to the nozzle 36) of the heating cylinder 31.

[0019] Hereinafter, among the range within which the tip position of the screw 32 can reach inside the heating cylinder 31, the position closest to the nozzle 36 is denoted as the "forward limit", and the position farthest from the nozzle 36 is denoted as the "retreat limit". Also, the terms "forward rotation" and "reverse rotation" of the injection motor do not specify the absolute rotation direction, but only specify the relative relationship (that is, forward rotation and reverse rotation are rotations in opposite directions).

[0020] The first hopper 33 and the second hopper 34 communicate with the resin passage 35 on the base end side from the tip of the heating cylinder 31. The first hopper 33 and the second hopper 34 are funnel-shaped members that supply the raw material of the molded product (hereinafter denoted as the "molding material") to the heating cylinder 31 (more specifically, the resin passage 35). The molding material includes pellets, which are resin materials molded into granular form, recycled resin, and reinforcing fibers. Also, the molding material may include resins of different colors. The first hopper 33 and the second hopper 34 supply different types of molding materials (for example, pellets and recycled resin, pellets of different colors, pellets and reinforcing fibers) to the heating cylinder 31.

[0021] The injection device 30 rotates the injection motor in reverse and rotates the metering motor, causing the screw 32 to retreat while rotating. As a result, the molding material supplied through the first hopper 33 and the second hopper 34 is plasticized and moves forward along the spiral groove 43, filling (metering) the resin passage 35 in front of the screw 32. In this process, the resins supplied from the first hopper 33 and the second hopper 34 are mixed at a predetermined ratio. Also, the injection device 30 rotates the injection motor forward, causing the screw 32 to advance. As a result, the plasticized resin filled in the resin passage 35 in front of the screw 32 is injected into the cavity of the mold 21 through the nozzle 36.

[0022] Figure 2 is an exploded view of the heating cylinder 31, screw 32, first hopper 33, and second hopper 34. Figure 3 is a diagram showing the positional relationship between the heating cylinder 31, screw 32, first hopper 33, and second hopper 34. Hereinafter, of the two ends of the heating cylinder 31 and screw 32 in the extension direction, the side closer to the nozzle 36 will be referred to as the "tip," and the opposite side will be referred to as the "base."

[0023] As shown in Figure 2, the heating cylinder 31 has housing holes 37 and 38 formed therein. The housing holes 37 and 38 penetrate the heating cylinder 31 radially at positions spaced apart in the extending direction of the heating cylinder 31. That is, the housing holes 37 and 38 connect the outer surface of the heating cylinder 31 to the resin passage 35. The heating cylinder 31 is then fixed with the housing holes 37 and 38 facing upward.

[0024] The housing hole 37 accommodates the first hopper 33. The housing hole 38 accommodates the second hopper 34. That is, the second hopper 34 is positioned closer to the tip of the heating cylinder 31 than the first hopper 33. Furthermore, the first hopper 33 and the second hopper 34 are configured to be detachably attached to the heating cylinder 31 at positions spaced apart in the extending direction of the heating cylinder 31.

[0025] The first hopper 33 has a frustoconical shape with an upper opening 33u and a lower opening 33l. The area of ​​the lower opening 33l is smaller than that of the upper opening 33u. The first hopper 33 is housed in the receiving hole 37 with its lower opening 33l facing downwards. As a result, the molding material (hereinafter referred to as "molding material 1") that enters the first hopper 33 through the upper opening 33u is supplied to the resin passage 35 through the lower opening 33l and the receiving hole 37.

[0026] The second hopper 34 has a frustoconical shape with an upper opening 34u and a lower opening 34l. The area of ​​the lower opening 34l is smaller than that of the upper opening 34u. The second hopper 34 is housed in the receiving hole 38 with its lower opening 34l facing downwards. As a result, the molding material (hereinafter referred to as "molding material 2") that enters the second hopper 34 through the upper opening 34u is supplied to the resin passage 35 through the lower opening 34l and the receiving hole 38. In other words, the second hopper 34 supplies the molding material 2 to the tip side of the heating cylinder 31 from the first hopper 33.

[0027] The screw 32 consists of a shaft portion 41 and a projection 42. The shaft portion 41 has a cylindrical outer shape that extends in a straight line. The projection 42 protrudes radially outward from the outer circumferential surface of the shaft portion 41 and extends spirally with respect to the direction of extension of the shaft portion 41. The space enclosed by the outer circumferential surface of the shaft portion 41 and the side surface of the projection 42 forms a spiral groove 43.

[0028] The shaft portion 41 according to this embodiment is composed of a large-diameter portion 41a and a small-diameter portion 41b. The external dimensions of the small-diameter portion 41b are smaller than those of the large-diameter portion 41a. Furthermore, the small-diameter portion 41b is located closer to the tip than the large-diameter portion 41a. In addition, the large-diameter portion 41a and the small-diameter portion 41b extend in the same direction. On the other hand, the external dimensions of the projection 42 are the same throughout the entire extension direction of the screw 32.

[0029] Hereinafter, the large-diameter portion 41a of the screw 32 will be referred to as the "first portion 44," and the small-diameter portion 41b will be referred to as the "second portion 45." That is, the second portion 45 is the portion of the screw 32 that is closer to the tip than the first portion 44. Furthermore, the second portion 45 is the portion in which the volume per unit length of the helical groove 43 is greater than that of the first portion 44. In this embodiment, the second portion 45 has a deeper helical groove 43 (radial dimension) than the first portion 44.

[0030] Furthermore, as shown in Figure 3, the first section 44 faces the first hopper 33, and the second section 45 faces the second hopper 34. More specifically, as shown in Figure 3(A), the boundary 46 between the first section 44 and the second section 45 is located in front of the first hopper 33 when the screw 32 is at its retraction limit. Also, as shown in Figure 3(B), the boundary 46 between the first section 44 and the second section 45 is located behind the second hopper 34 when the screw 32 is at its forward limit. In other words, the first section 44 always faces the first hopper 33, and the second section 45 always faces the second hopper 34.

[0031] As a result, when the screw 32 rotates and retracts, the molding material 1 supplied from the first hopper 33 moves forward along the helical groove 43 of the first section 44 while being plasticized. However, since the volume per unit length of the helical groove 43 is larger in the second section 45 than in the first section 44, as shown by the dot hatching in Figure 3(A), the molding material 1 completely fills the helical groove 43 of the first section 44, but when it moves to the second section 45, it only fills a portion of the helical groove 43 of the second section 45. Consequently, the molding material 2 supplied from the second hopper 34 can enter the helical groove 43 of the second section 45. The molding materials 1 and 2 are then mixed in the second section 45 and filled into the area on the tip side of the screw 32.

[0032] Furthermore, by adjusting the ratio of the volume V1 per unit length of the helical groove 43 of the first part 44 to the volume V2 per unit length of the helical groove 43 of the second part 45, the mixing ratio of the molding material 1 supplied from the first hopper 33 and the molding material 2 supplied from the second hopper 34 can be adjusted. In other words, the mixing ratio of the molding materials 1 and 2 will be approximately close to V1:V2.

[0033] However, it is difficult to precisely adjust the mixing ratio of molding materials 1 and 2 solely by the ratio of volumes V1 and V2. Therefore, the mixing ratio of molding materials 1 and 2 can be finely adjusted by varying the shapes of the first hopper 33 and the second hopper 34. Figure 4 shows variations of hoppers 51 to 54. In other words, any of the hoppers 51 to 54 shown in Figure 4 can be used as the first hopper 33 and the second hopper 34. Furthermore, the specific shapes of the first hopper 33 and the second hopper 34 are not limited to the examples in Figure 4.

[0034] The area of ​​the lower end opening 51l of hopper 51 shown in Figure 4(A) is larger than the area of ​​the lower end opening 52l of hopper 52 shown in Figure 4(B). In other words, by combining the first hopper 33 and the second hopper 34, which have different lower end openings 33l and 34l, the mixing ratio of molding materials 1 and 2 can be finely adjusted. More specifically, if you want to increase the mixing ratio of molding material 1, you should make the area of ​​the lower end opening 33l of the first hopper 33 larger than the area of ​​the lower end opening 34l of the second hopper 34. On the other hand, if you want to increase the mixing ratio of molding material 2, you should make the area of ​​the lower end opening 34l of the second hopper 34 larger than the area of ​​the lower end opening 33l of the first hopper 33.

[0035] Furthermore, the hoppers 51 and 52 shown in Figures 4(A) and 4(B) supply molding material to the heating cylinder 31 in a region that includes a straight line L extending vertically through the center of the heating cylinder 31 when viewed from the direction of extension of the heating cylinder 31. In other words, the lower end openings 51l and 52l of the hoppers 51 and 52 are positioned to include the straight line L when viewed from the direction of extension of the heating cylinder 31.

[0036] Furthermore, the hopper 53 shown in Figure 4(C) supplies molding material to the heating cylinder 31 in a region upstream of the straight line L in the direction of rotation of the screw 32 (clockwise in the example of Figure 4, indicated by the arrow) when viewed from the extending direction of the heating cylinder 31. In other words, the lower end opening 53l of the hopper 53 is located upstream of the straight line L in the direction of rotation of the screw 32 when viewed from the extending direction of the heating cylinder 31.

[0037] Furthermore, the hopper 54 shown in Figure 4(D) supplies molding material to the heating cylinder 31 in a region downstream of the straight line L in the direction of rotation of the screw 32, when viewed from the extending direction of the heating cylinder 31. In other words, the lower end opening 54l of the hopper 54 is located downstream of the straight line L in the direction of rotation of the screw 32, when viewed from the extending direction of the heating cylinder 31.

[0038] Furthermore, the more the molding material is supplied from the upstream region in the rotational direction of the screw 32, the greater the amount of molding material supplied. Therefore, by combining the first hopper 33 and the second hopper 34, which have different supply positions for the molding material to the heating cylinder 31 in the circumferential direction of the heating cylinder 31 (in other words, in the rotational direction of the screw 32), the mixing ratio of the molding materials 1 and 2 can be finely adjusted.

[0039] More specifically, if you want to increase the mixing ratio of molding material 1, you should select the first hopper 33, whose lower end opening 33l is located upstream of the screw 32 in the direction of rotation, and the second hopper 34, whose lower end opening 34l is located downstream of the screw 32 in the direction of rotation. On the other hand, if you want to increase the mixing ratio of molding material 2, you should select the second hopper 34, whose lower end opening 34l is located upstream of the screw 32 in the direction of rotation, and the first hopper 33, whose lower end opening 33l is located downstream of the screw 32 in the direction of rotation.

[0040] [Effects of the Embodiment] According to the above embodiment, by making the volume per unit length of the helical groove 43 of the second part 45 larger than that of the helical groove 43 of the first part 44, the molding materials 1 and 2 can be supplied to the heating cylinder 31 (resin passage 35) from the first hopper 33 and the second hopper 34 in appropriate proportions. This makes it possible to mold a molded product in which the molding materials 1 and 2 are mixed in a desired proportion.

[0041] Furthermore, according to the above embodiment, by always positioning the first part 44 facing the first hopper 33 and the second part 45 facing the second hopper 34, the mixing ratio of the molding materials 1 and 2 can be stabilized regardless of the position of the screw 32.

[0042] Furthermore, according to the above embodiment, the mixing ratio of molding materials 1 and 2 can be finely adjusted by varying the shapes of the first hopper 33 and the second hopper 34 (more specifically, the supply amounts of molding materials 1 and 2 to the first hopper 33 and the second hopper 34). This makes it possible to bring the mixing ratio of molding materials 1 and 2 closer to a desired value.

[0043] [Differentiation] In the above embodiment, an example of a screw 32 was described in which the depth of the helical groove 43 of the second part 45 is deeper than that of the first part 44. However, the specific method for making the volume per unit length of the helical groove 43 of the second part 45 larger than that of the helical groove 43 of the first part 44 is not limited to the example in Figure 2. Figure 5 shows the shapes of screws 32A and 32B according to modified examples. In the example in Figure 5, the width of the helical groove 43 of the second part 45 is wider than the width of the helical groove 43 of the first part 44.

[0044] As shown in Figure 5(A), the diameter of the shaft portion 41A of the screw 32A is the same throughout its entire extension direction. On the other hand, the pitch P2 of the ridges 42A of the second portion 45A of the screw 32A is wider than the pitch P1 of the ridges 42A of the first portion 44A. The pitches P1 and P2 of the ridges 42A are the distance in the extension direction until the ridges 42A complete a full rotation around the shaft portion 41A. In this way, the volume per unit length of the helical groove 43 can be adjusted by changing the pitches P1 and P2 of the ridges 42A.

[0045] As shown in Figure 5(B), the diameter of the shaft portion 41B of the screw 32B is the same throughout its entire extension direction. On the other hand, the width W2 of the projection 42B of the second portion 45B of the screw 32B is narrower than the width W1 of the projection 42B of the first portion 44B. In this way, the volume per unit length of the helical groove 43 can be adjusted by changing the widths W1 and W2 of the projections 42B.

[0046] Furthermore, the specific method for making the volume per unit length of the helical groove 43 of the second part 45 larger than that of the helical groove 43 of the first part 44 is not limited to the example described above, and the number of ridges 42 may be changed between the first part 44 and the second part 45. In addition, the screw shapes described herein may be combined.

[0047] Furthermore, the injection device 30 may include three or more hoppers. For example, if it includes three hoppers spaced apart in the extending direction of the heating cylinder 31, the screw 32 has a first part, a second part, and a third part facing each hopper. The volume per unit length of the helical groove 43 of each part should be larger towards the tip of the screw 32.

[0048] The embodiments described above are illustrative for explaining the present invention and are not intended to limit the scope of the invention to those embodiments only. Those skilled in the art can implement the present invention in various other forms without departing from the spirit of the invention. [Explanation of symbols]

[0049] 10...Injection molding machine, 20...Clamping device, 21...Mold, 22...Fixed side mold, 23...Fixed die plate, 24...Movable side mold, 25...Movable die plate, 26...Toggle link mechanism, 27...Tie bar, 30...Injection device, 31...Heating cylinder, 32,32A,32B...Screw, 33...First hopper, 33l,34l,51l,52l,53l,54l...Lower end opening, 33u, 34u… Upper end opening, 34… Second hopper, 35… Resin passage, 36… Nozzle, 37, 38… Housing hole, 41, 41A, 41B… Shaft section, 41a… Large diameter section, 41b… Small diameter section, 42, 42A, 42B… Protrusion, 43, 43A, 43B… Helical groove, 44, 44A, 44B… First section, 45, 45A, 45B… Second section, 46… Boundary, 51, 52, 53, 54… Hopper

Claims

1. In an injection molding device that injects molding material into the cavity of a clamped mold, A heating cylinder filled with molding material, A first hopper that supplies molding material to the heating cylinder, A second hopper supplies molding material from the first hopper to the tip side of the heating cylinder, A screw has a helical groove formed on its outer surface and rotates and retracts inside the heating cylinder to measure the molding material, and moves forward inside the heating cylinder to inject the molding material into the cavity. The aforementioned screw is The first part facing the first hopper, An injection device characterized by having a second portion facing the second hopper, wherein the volume per unit length of the helical groove is larger than that of the first portion.

2. In the injection apparatus according to claim 1, The aforementioned screw is A shaft portion extending in a straight line, The shaft portion has a projection that extends radially outward from its outer circumferential surface and is spirally extended, The second part is characterized in that, compared to the first part, the depth of the helical groove is greater, the pitch of the protrusions is wider, or the width of the protrusions is narrower.

3. In the injection apparatus according to claim 1, The boundary between the first part and the second part is, When the screw is at its retraction limit, it is located in front of the first hopper, An injection device characterized in that it is located behind the second hopper when the screw is in its forward position.

4. In the injection apparatus according to claim 1, The injection device is characterized in that the first hopper and the second hopper have different areas of lower end openings for supplying molding material to the heating cylinder.

5. In the injection apparatus according to claim 1, The injection molding apparatus is characterized in that the first hopper and the second hopper have different supply positions for the molding material to the heating cylinder when viewed from the direction of extension of the heating cylinder.

6. A mold clamping device that opens and closes the mold and clamps it, A molding machine characterized by comprising the injection device described in claim 1.

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