Vertical injection molding device

Abstract

A vertical injection molding device (10) is provided with: a mold clamping device (20) in which a mold clamping axis (20a) is vertical; a turntable (23) on which a lower mold (13) is mounted and moves between a mold clamping position and a product take-out position; and an injection device (50) in which an injection axis (50a) is vertical, wherein the injection device (50) has: a left and right pair of a first heating cylinder (53L) and a second heating cylinder (53R); and a Y-shaped adapter (80) that is connected under the first heating cylinder (53L) and the second heating cylinder (53R), merges the resin material from the first heating cylinder (53L) and the resin material from the second heating cylinder (53R), and injects the merged resin material from a single nozzle (53a).

Description

Vertical injection molding equipment

[0001] The present invention relates to an improved technology for a vertical injection molding machine.

[0002] Injection molding machines that inject resin material into a mold to produce a resin molded product (hereinafter referred to as a product) are widely used. Injection molding machines are classified into horizontal injection molding machines and vertical injection molding machines. A known vertical injection molding machine is a turntable-type vertical injection molding machine that has a turntable (see, for example, Patent Document 1 (FIG. 1)).

[0003] Patent Document 1 will be described with reference to the following figure. Figure 8 is a side view of a conventional turntable-type vertical injection molding apparatus. As shown in Figure 8, this vertical injection molding apparatus 101 has a turntable 103 on a bed 102, and mold clamping devices 104 on the bed 102, sandwiching the turntable 103. An injection device 105 is provided above the mold clamping device 104.

[0004] A mold clamping shaft 106 of the mold clamping unit 104 and an injection shaft 107 of the injection unit 105 are both vertical and share a common axis. On the turntable 103, the portion overlapping with the mold clamping shaft 106 is a mold clamping position 109, and the portion symmetrical about a rotation axis 111 is a product removal position 112 where a product is removed.

[0005] An upper mold 113 and a first lower mold 114 are arranged along a mold clamping shaft 106. At this time, a second lower mold 115 is arranged at a product removal position 112. The upper mold 113 is aligned with the first lower mold 114, and the molds are clamped by a mold clamping device 104, and a resin material is injected from a heating barrel 116 of an injection device 105.

[0006] Once the resin material has hardened, the upper mold 113 is raised and the turntable 103 is rotated 180°. Then, the first lower mold 114 moves to the product removal position 112, and the product is removed in this state. As the turntable 103 rotates, the second lower mold 115 moves to the mold clamping position 109. The next injection molding is performed using this second lower mold 115 and upper mold 113.

[0007] The turntable system has the advantage of increasing production efficiency because the injection of resin material and the removal of the product are performed simultaneously. However, as the product becomes larger, the injection device 105 becomes larger. Specifically, the outer diameter and axial length of the heating barrel 116 become larger. As the axial length increases, the height H1 of the vertical injection molding device 101 also increases.

[0008] If the ceiling of the building in which the vertical injection molding apparatus 101 is installed is low, the vertical injection molding apparatus 101, which has a large height H1, cannot be installed. In this case, an injection molding apparatus with a small height is required. Various turntable-type injection molding apparatuses with small heights have been put into practical use (see, for example, Patent Document 2 (FIG. 4)).

[0009] Patent Document 2 will be explained with reference to the following figure. Figure 9 is a front view of another conventional turntable-type injection molding apparatus. As shown in Figure 9, this injection molding apparatus 121 has a turntable 123 on a bed 122, and mold clamping devices 124 on the bed 122 so as to sandwich this turntable 123. An injection device 125 is provided next to the mold clamping device 124.

[0010] The clamping shaft 126 of the clamping unit 124 is vertical, and the injection shaft 127 of the injection unit 125 is horizontal. Even if the axial length of the injection unit 125 increases with the increase in product size, the height H2 of the injection molding unit 121 remains almost constant and can be kept small. Therefore, Patent Document 2 provides an injection molding unit 121 that can be installed in a building with a low ceiling, even when products are becoming larger.

[0011] However, the injection molding apparatus 121 of Patent Document 2 has the following drawbacks. As the size of the product increases, the horizontal length L2 of the injection molding apparatus 121 increases. When the horizontal length L2 increases, the so-called floor area required increases. When the floor area increases, it becomes impossible to install the required number of injection molding apparatuses 121 in a building with a certain floor area. When the number of injection molding apparatuses 121 decreases, productivity decreases.

[0012] 8, the horizontal length L1 is sufficiently small, and the required number of units can be easily installed in a building with a certain floor area. Therefore, a turntable-type vertical injection molding apparatus that can reduce the height H1 while ensuring a sufficiently large injection volume is desired.

[0013] Patent No. 5781675 Publication JP-A-8-174594

[0014] An object of the present invention is to provide a turntable-type vertical injection molding machine equipped with a vertical injection unit that can be made small in height while ensuring a sufficiently large injection volume.

[0015] The inventors of the present invention have tried various methods to reduce the height of a turntable-type vertical injection molding machine. Through these attempts, they discovered that by replacing one heating barrel with two, they could reduce the height of the injection molding machine while maintaining the injection volume. The process of this discovery is explained in the following diagram.

[0016] 1A has a sufficiently large injection volume. The axial length, i.e., height, of the heating barrel 128 is Ha. We will consider replacing this heating barrel 128 with two heating barrels.

[0017] 1B, the heating barrel 128 is replaced with a first heating barrel 53L and a second heating barrel 53R. The first heating barrel 53L has a smaller diameter and length because its injection volume is half that of the heating barrel 128. The same applies to the second heating barrel 53R.

[0018] However, it is necessary to connect a joining adapter to the outlet of the first heating barrel 53L and the outlet of the second heating barrel 53R. A suitable adapter is a T-shaped adapter 130. The T-shaped adapter 130 allows the resin material injected from the first heating barrel 53L and the resin material injected from the second heating barrel 53R to be injected from the nozzle together.

[0019] However, the T-shaped adapter 130 has the following advantages and disadvantages. The T-shaped adapter 130 has the advantage of reducing the height dimension hb. On the other hand, it has the disadvantage that the resin material flowing through the first horizontal flow path 131 and the resin material flowing through the second horizontal flow path 132 directly collide from the left and right, disrupting the flow of the resin material.

[0020] Considering the flow of the resin material, it is desirable that the surfaces of the first horizontal flow path 131 and the second horizontal flow path 132 are smooth. However, the structure of the T-shaped adapter 130 makes it difficult to perform honing.

[0021] Honing is possible if the T-shaped adapter 130 is divided, but it must be divided into at least two locations, preferably four locations, and the divided parts must be joined with flanges or screws, which results in a complex structure of the T-shaped adapter 130.

[0022] In order to overcome the above-mentioned drawbacks, the inventors came up with the idea shown in Fig. 1(c). As shown in Fig. 1(c), the adapter is a Y-shaped adapter 80. However, the Y-shaped adapter 80 has the following drawbacks and advantages.

[0023] A disadvantage is that the height hc of the Y-shaped adapter 80 is greater than the height hb of the T-shaped adapter 130 .

[0024] As a result, as shown in Figures 1(a) to (c), the height Hc of the Y-shaped adapter 80 plus the first heated barrel 53L is greater than the height Hb of the T-shaped adapter 130 plus the first heated barrel 53L, but is sufficiently smaller than the height Ha of the heated barrel 128.

[0025] The advantages of the Y-shaped adapter 80 shown in Fig. 1(c) will be explained in detail with reference to Figs. 2(a) and 2(b). Fig. 2(a) is a cross-sectional view of the Y-shaped adapter according to the present invention, and Fig. 2(b) is a diagram illustrating the honing process.

[0026] 2(a), the Y-shaped adapter 80 is a member having two inlets and one outlet, and is made up of a V-shaped portion 81 connected to the tip (lower end) of the first heating barrel 53L and the tip (lower end) of the second heating barrel 53R with bolts or the like, and an I-shaped portion 82 hanging down from the V-shaped portion 81. The V-shaped portion 81 and the I-shaped portion 82 form a Y shape.

[0027] The V-shaped portion 81 and the I-shaped portion 82 are separable and are integrated by screw connection or flange connection. The I-shaped portion 82 is formed with a nozzle 53a in addition to a threaded portion 83.

[0028] The V-shaped portion 81 has a first downward flow path 84 connected to the first heating barrel 53L, a first diagonal flow path 85 extending diagonally from the lower end of the first downward flow path 84, a second downward flow path 86 connected to the second heating barrel 53R, and a second diagonal flow path 87 extending diagonally from the lower end of the second downward flow path 86.

[0029] The inclination angle θ of the first oblique flow channel 85 with respect to the vertical axis is preferably 45°. If the inclination angle θ is much greater than 45°, collisions between the resin materials may occur, while if the inclination angle θ is much less than 45°, the height dimension increases. As long as collisions between the resin materials are avoided and the increase in height dimension is within an allowable range, the inclination angle θ may be set to a value other than 45°. The same applies to the second oblique flow channel 87.

[0030] 2(b), the first downward flow passage 84 and the second downward flow passage 86 are open at the top, so that a grindstone 89 can be inserted from above. As a result, the surfaces of the first downward flow passage 84 and the second downward flow passage 86 are honed and made smooth.

[0031] The downward extension line 88 of the first diagonal flow passage 85 and the downward extension line 88 of the second diagonal flow passage 87 do not interfere with the wall of the V-shaped portion 81. As a result, the grindstone 89 can be inserted from below.

[0032] 2(a) and 2(b), the resin material flowing through the first diagonal flow passage 85 and the resin material flowing through the second diagonal flow passage 87 do not directly collide with each other and smoothly merge. In other words, this has the advantage of not disturbing the flow of the resin material. In addition, this has a second advantage in that the first diagonal flow passage 85 and the second diagonal flow passage 87 can be easily finished by honing or other processes.

[0033] The invention completed based on the above findings is as follows: The invention according to claim 1 is a vertical injection molding apparatus comprising: a mold clamping device having a vertical mold clamping axis that clamps an upper mold to a lower mold; a turntable that carries the lower mold and moves between a mold clamping position and a product removal position; and an injection device having a vertical injection axis that is disposed above the mold clamping device and that injects a resin material into a mold consisting of the lower mold and the upper mold, wherein the injection device has a pair of left and right first and second heating barrels, and a Y-shaped adapter that is connected below the first and second heating barrels and that joins the resin material from the first and second heating barrels and injects the joined resin material from the first and second heating barrels from a single nozzle.

[0034] Preferably, the invention according to claim 2 is the vertical injection molding apparatus according to claim 1, wherein the Y-shaped adapter comprises a V-shaped portion connected to the bottom of the first heating barrel and the second heating barrel, and an I-shaped portion detachably connected to the V-shaped portion and including the nozzle, the V-shaped portion having a first diagonal flow path and a second diagonal flow path, and downward extension lines extending downward from the first diagonal flow path and the second diagonal flow path do not interfere with the material of the V-shaped portion.

[0035] Preferably, the invention according to claim 3 is the vertical injection molding apparatus according to claim 1 or claim 2, wherein the mold clamping device comprises a pressure platen fixed to a bed, a traction platen arranged below the pressure platen and raised and lowered by a half nut position adjustment mechanism, a movable platen arranged above the pressure platen and raised and lowered by a mold opening and closing mechanism, and a tie bar lowered from the movable platen and passing through the pressure platen and the traction platen, and is an apparatus for clamping the mold arranged between the pressure platen and the movable platen, wherein an engagement portion is provided at the lower end of the tie bar, and a half nut that engages with the engagement portion is provided below the traction platen.

[0036] In the invention according to claim 1, in a turntable-type vertical injection molding machine, the heating barrel extending upward is composed of a pair of first and second heating barrels on the left and right. By dividing one heating barrel into two, the height of the first and second heating barrels can be significantly reduced. The injection volume is the sum of the injection volume of the first heating barrel and the injection volume of the second heating barrel, ensuring a sufficient size.

[0037] In addition, the resin material from the first heating barrel and the resin material from the second heating barrel are joined by a Y-shaped adapter and injected from a single nozzle, which prevents the resin materials from colliding with each other and allows for smooth injection.As a result, claim 1 provides a turntable-type vertical injection molding machine equipped with a vertical injection unit that can reduce the height while ensuring a sufficiently large injection volume.

[0038] In the invention according to claim 2, the V-shaped portion, which is a key part of the Y-shaped adapter, is designed so that the downward extensions of the first diagonal flow path and the second diagonal flow path do not interfere with the wall of the V-shaped portion, making it easy to insert a grindstone into the first diagonal flow path and the second diagonal flow path. The grindstone can smooth the surfaces of the first diagonal flow path and the second diagonal flow path. Smooth surfaces allow for smooth flow of the resin material.

[0039] In the invention according to claim 3, half nuts are used. The half nut system allows the height to be smaller than the vertical injection molding apparatus 101 shown in Figure 8. In addition to configuring the heating barrel as a pair of first and second heating barrels on the left and right, the use of half nuts allows the height of a turntable type vertical injection molding apparatus to be even smaller.

[0040] (a) to (c) are diagrams explaining the process by which the present invention was completed. (a) is a cross-sectional view of a Y-shaped adapter according to the present invention, and (b) is a diagram explaining honing processing. A diagram showing the overall configuration of a vertical injection molding apparatus according to the present invention. A view taken along line 4-4 in FIG. 3. A diagram explaining the operation of a vertical injection molding apparatus. (a) and (b) are diagrams explaining the operation of an injection device, which is one element of a vertical injection molding apparatus. (a) is a diagram showing a modified example of a Y-shaped adapter, and (b) is a diagram explaining the operation of a check valve. A side view of a conventional turntable-type vertical injection molding apparatus. A front view of another conventional turntable-type injection molding apparatus.

[0041] An embodiment of the present invention will be described below with reference to the accompanying drawings. Regarding a cylinder, "extension" means that the piston rod is advanced to extend the overall length of the cylinder, and "retraction" means that the piston rod is retracted to shorten the overall length of the cylinder.

[0042] As shown in FIG. 3, the vertical injection molding apparatus 10 is an apparatus whose main elements are a mold clamping unit 20 having a vertical mold clamping axis 20a that clamps a mold 12 consisting of a lower mold 13 and an upper mold 14, and an injection unit 50 having a vertical injection axis 50a that is disposed vertically above the mold clamping unit 20.

[0043] The mold clamping device 20 includes a bed 21 fixed to the floor (or machine base) 16, a pressure platen 22 fixed to the bed 21, a turntable 23 placed on the pressure platen 22, a traction platen 79 arranged below the pressure platen 22 and raised and lowered by a half nut position adjustment mechanism 24 provided on the pressure platen 22, half nuts 26 arranged below the traction platen 79 including a mold clamping cylinder 33, a movable platen 28 arranged above the pressure platen 22 and raised and lowered by a mold opening and closing mechanism 27 provided on the pressure platen 22, tie bars 31 lowered from the movable platen 28 and passing through the pressure platen 22 and the traction platen 79, and a pump motor unit 32 that supplies pressure oil to the half nut position adjustment mechanism 24, the mold clamping cylinder 33, the mold opening and closing mechanism 27, etc.

[0044] The half nut position adjusting mechanism 24 is preferably a half nut position adjusting hydraulic cylinder 24A. Similarly, the mold clamping mechanism 25 is preferably a mold clamping cylinder 33, and the mold opening and closing mechanism 27 is preferably a mold opening and closing hydraulic cylinder 27A.

[0045] The pressure platen 22 can be removed from the bed 21 by loosening bolts, etc. Therefore, the term "fixed" in this invention includes not only complete fixation but also a form in which it is separably connected. Also, the half nut position adjustment mechanism 24 and the mold opening / closing mechanism 27 may be provided on the bed 21.

[0046] The mold clamping mechanism 25 has, for example, a mold clamping cylinder 33 that opens upward. A piston portion 34 that extends downward from the pressure receiving platen 22 is housed in this mold clamping cylinder 33. An oil pressure chamber 35 is formed between the mold clamping cylinder 33 and the piston portion 34. When pressure oil is supplied to the oil pressure chamber 35, the traction platen 79 is lowered.

[0047] The tie bar 31 has an engaging portion 36 at its lower end. This engaging portion 36 is, for example, a sawtooth portion. Hereinafter, the engaging portion 36 will be read as the sawtooth portion 36. The half nuts 26 are split nuts that engage (mesh) with the sawtooth portion 36 serving as the engaging portion. The half nuts 26 are opened and closed by a half nut opening and closing mechanism 37 provided on the traction disk 79. The half nut opening and closing mechanism 37 is preferably a half nut opening and closing hydraulic cylinder 37A.

[0048] The saw-tooth portion 36 preferably has teeth arranged at equal intervals, like the joints of a bamboo. The teeth may have a rectangular, trapezoidal, or triangular cross section. The half nuts 26 are provided with corresponding teeth.

[0049] The tie bar 31 and half nut 26 are made of strong, hard steel. To ensure smooth contact between the steel, grease is applied between the sawtooth portion 36 and the half nut 26. The grease is applied to the outer surface of the tie bar 31 at a position higher than the sawtooth portion 36. The grease flows down and reaches the sawtooth portion 36. Greasing can be done automatically or manually.

[0050] Preferably, a half nut operation monitoring mechanism 38 that monitors the operation of the half nuts 26 is provided near the half nuts 26. However, the half nut operation monitoring mechanism 38 may be omitted provided that the positions of the mold opening / closing mechanism 27 and the half nut position adjusting mechanism 24 can be precisely controlled.

[0051] The half nut operation monitoring mechanism 38 can use any type of sensor, such as a proximity switch or limit switch. Among these, a proximity switch is a non-contact sensor that determines whether an object is present when the mating metal is within a certain distance and whether an object is absent when the mating metal is further away than a certain distance. The half nut 26 is wet with waste grease, but a non-contact sensor eliminates the risk of false detection. Furthermore, it is inexpensive. Therefore, a proximity switch is recommended.

[0052] Preferably, a tray 41 for receiving the waste grease is placed below the half nuts 26 and on the floor 16. The tray 41 is a dish-shaped container. The tray 41 is pulled out periodically or as needed to dispose of the accumulated waste grease, thereby preventing the floor 16 from becoming dirty.

[0053] Preferably, the bed 21 is surrounded by a cover 42. This cover 42 serves as a safety cover. Surrounding the bed 21 with the cover 42 improves the appearance of the mold clamping unit 20. However, the cover 42 is not essential because it can be replaced with a safety fence or the like.

[0054] The injection device 50 comprises an injection device moving mechanism 51 erected on the movable platen 28, an injection table 52 supported by this injection device moving mechanism 51, a first heating barrel 53L and a second heating barrel 53R supported by this injection table 52 and extending downward, a Y-shaped adapter 80 connected to the ends (the lower ends in the figure) of these, an injection mechanism 54 provided on the injection table 52 and having a piston rod extending upward, a first screw drive table 55L and a second screw drive table 55R supported by this injection mechanism 54, a first screw rotation mechanism 56L and a second screw rotation mechanism 56R supported by the first screw drive table 55L and the second screw drive table 55R, and a first screw 57L and a second screw 57R extending downward from the first screw rotation mechanism 56L and the second screw rotation mechanism 56R and entering the first heating barrel 53L and the second heating barrel 53R.

[0055] For convenience, the longitudinal center axis of the first heating barrel 53L and the second heating barrel 53R is defined as the injection axis 50a. The Y-shaped adapter 80 functions to join the resin material from the first heating barrel 53L and the resin material from the second heating barrel 53R and inject the combined resin material from the single nozzle 53a.

[0056] The first screw rotation mechanism 56L and the second screw rotation mechanism 56R are, for example, hydraulic motors.

[0057] The injection unit moving mechanism 51 is preferably an injection unit moving hydraulic cylinder 51A, and the injection mechanism 54 is preferably an injection cylinder 54A.

[0058] More preferably, a purging cover 64 that surrounds the first heating barrel 53L and the second heating barrel 53R is provided on the movable platen 28. An upper die ejector 60 is also provided on the movable platen 28. This upper die ejector 60 is made up of ejector pins 61 that extend to the upper die 14 and a pin moving mechanism 62 that moves the ejector pins 61, and plays a role in pushing down any runners remaining in the upper die 14. The pin moving mechanism 62 is preferably a pin moving hydraulic cylinder 62A, but it may also be an electric cylinder.

[0059] Figure 4 is a view taken along line 4-4 in Figure 3. As shown in Figure 4, tie bars 31 are arranged at the vertices of a triangle. One of the tie bars 31 forms the center of rotation of the turntable 23. At the product removal position 17, the product is removed from the lower mold 13. The empty lower mold 13 is moved to the mold clamping position 18 by rotating the turntable 23 by 180 degrees. Because the product removal operation and mold clamping operation can be performed in parallel, the use of the turntable 23 can increase productivity.

[0060] In the mold clamping unit 20 of Fig. 3, the half nuts 26 are opened and separated from the sawtooth portion 36. Next, the mold opening / closing mechanism 27 is extended to lift the movable platen 28. As the movable platen 28 lifts, the upper mold 14 is separated from the lower mold 13 and the tie bars 31 are lifted. Also, in the injection unit 50, the injection unit moving mechanism 51 is extended to lift the injection table 52. As the injection table 52 lifts, the first heating barrel 53L and the second heating barrel 53R lift.

[0061] The above results are shown in Figure 5. As shown in Figure 5, which shows the maximum mold open state, the lower end portions 31a of the tie bars 31 rise up into the traction disk 79. As a result, the tie bars 31 can be made sufficiently short. If the tie bars 31 are short, the tie bars 31 become lighter and material can be saved. That is, in the conventional technology, a structure in which the lower end portions 31a of the tie bars 31 always extend outside the traction disk 79 is preferred. In contrast, with Figure 5, the tie bars 31 can be made significantly shorter.

[0062] When the tie bars 31 are shortened, the height of the mold clamping unit 20 is reduced. When the height of the mold clamping unit 20 is reduced, the height of the vertical injection molding apparatus 10 is reduced. In other words, by changing one heating barrel to two, the first heating barrel 56L and the second heating barrel 56R, the height of the injection unit 50 is reduced and the tie bars 31 are shortened. As a result, the height of the mold clamping unit 20 is reduced, and the height of the vertical injection molding apparatus 10 is further reduced.

[0063] Furthermore, a purging operation may be performed in which the first heating barrel 53L and the second heating barrel 53R are raised to discharge the accumulated resin material. This purging operation is also called a waste shot process. In the waste shot process, the resin material is ejected from the nozzle 53a, but the purging cover 64 prevents it from scattering. The worker opens the purging cover 64 as needed or as appropriate to remove the accumulated resin material. According to the present invention, the purging cover 64 that surrounds the nozzle 53a can be easily positioned on the movable platen 28.

[0064] In the vertical injection molding apparatus 10, the operation of the mold clamping unit 20 and the operation of the injection unit 50 are carried out in parallel. First, the operation of the mold clamping unit 20 will be described. In Figure 5, the mold opening and closing mechanism 27 is contracted to lower the movable platen 28, upper mold 14, and tie bars 31. When the upper mold 14 hits the lower mold 13, the lowering of the tie bars 31 and the like is completed.

[0065] There is a phase misalignment between the sawtooth portion 36 and the half nut 26. The half nut position adjustment mechanism 24 is used to slightly raise and lower the traction plate 79 so that this phase becomes zero. Once the adjustment is complete, the half nut opening and closing mechanism 37 is extended to engage the half nut 26 with the sawtooth portion 36. If there is any misalignment, this is detected by the half nut operation monitoring mechanism 38. If there is a misalignment, the injection molding operation is stopped and corrective measures are taken.

[0066] If no misalignment is detected, pressure oil is supplied to the oil pressure chamber 35 of the clamping cylinder 33 in Figure 3. This causes the traction platen 79 to move down, the tie bars 31 to move down, and the movable platen 28 to move down. In this way, the mold 12 is clamped.

[0067] Next, the operation of the injection device 50 will be described with reference to Figures 5 and 6. In Figure 5, the first screw 57L and the second screw 57R are rotated in a predetermined direction at a predetermined speed by the first screw rotation mechanism 56L and the second screw rotation mechanism 56R. Resin material is supplied to the first heating barrel 53L and the second heating barrel 53R via a hopper 65. The resin material descends through the grooves of the first screw 57L and the grooves of the second screw 57R. The resin material is heated and kneaded to become plastic.

[0068] The resin material accumulates below the first screw 57L and the second screw 57R in the first heating barrel 53L and the second heating barrel 53R. The reaction force from this accumulation causes the first screw 57L and the second screw 57R to gradually rise. The measured value is the value obtained by multiplying the cross-sectional area of ​​the first screw 57L and the second screw 57R by the amount of movement of the screw. When this measured value reaches a predetermined value, the plasticization and metering process is completed.

[0069] Figure 6(a) is a diagram showing the state when the plasticization and metering process is completed, and in Figure 6(a), the injection device movement mechanism 51 is retracted. As shown in Figure 6(b), the nozzle 53a comes into contact with a predetermined position on the upper mold 14. Next, the injection mechanism 54 is retracted, and the first screw 57L and the second screw 57R are advanced (depressed). The resin material is injected into the upper mold 14 by the advancing first screw 57L and second screw 57R.

[0070] Furthermore, since the bed 21 is enclosed by the cover 42, the appearance of the mold clamping unit 20 can be improved. However, this makes it difficult to visually inspect the half nuts 26. In the present invention, the half nut operation monitoring mechanism 38 monitors the operation of the half nuts 26, making visual inspection unnecessary and maintaining stable operation of the mold clamping unit 20.

[0071] The vertical injection molding apparatus 10 is also composed of the mold clamping unit 20 and the injection unit 50 disposed vertically above the movable platen 28. If the half nuts 26 were located on the movable platen 28 in the mold clamping unit 20, the injection unit 50 (particularly the first heating barrel 53L and the second heating barrel 53R) would interfere with the half nuts 26, making it difficult to dispose the injection unit 50 above the movable platen 28. Forcing the injection unit 50 to be disposed in this manner would complicate the structure around the movable platen 28. In this regard, according to the present invention, the space above the movable platen 28 is open, making it easy to dispose the injection unit 50 above the movable platen 28. In addition to the injection unit 50, a purging cover 42, an upper mold ejector 60, and the like can be disposed on the movable platen 28.

[0072] An improved version of the Y-shaped adapter 80 described with reference to Figures 2(a) and 2(b) will be described with reference to Figures 7(a) and 7(b). As shown in Figure 7(a), the Y-shaped adapter 80 includes a needle 91 that closes the nozzle 53a, and a valve opening / closing hydraulic cylinder 92 provided in the V-shaped portion 81 for raising and lowering the needle 91.

[0073] Injection molding involves the following steps, in that order: an injection process in which resin material is injected into the mold cavity; a pressure holding process in which back pressure is applied to the injected resin material; and a metering process in which the first screw 57L and the second screw 57R are rotated and retracted to measure the resin material. During the metering process, the nozzle 53a is closed by the needle 91. At the start of the injection process, the needle 91 is raised, the nozzle 53a is opened, and injection is performed. The needle 91 remains raised during the pressure holding process. Once pressure holding is complete, the needle 91 is lowered to close the nozzle 53a.

[0074] The stroke of the needle 91 (the distance traveled when opening and closing) may be about 1.0 to 2.0 times the outer diameter of the needle 91. If it is about this size, the valve opening and closing hydraulic cylinder 92 will not be large.

[0075] Preferably, a first check valve 93L is interposed between the first heating barrel 53L and the V-shaped portion 81, and a second check valve 93R is interposed between the second heating barrel 53R and the V-shaped portion 81.

[0076] 7(b), the first check valve 93L comprises a cylindrical valve box 94, an upper perforated plate 95 screwed or otherwise fitted into the upper opening of the cylindrical valve box 94, a lower perforated plate 96 screwed or otherwise fitted into the lower opening of the valve box 94, and a ball 97 housed in the valve box 94 so as to be able to move up and down. The upper perforated plate 95 has a hole 95a in its center. The lower perforated plate 96 has, in addition to the central hole 96a, sub-holes 96b positioned surrounding the hole 96a.

[0077] Ball 97 moves up and down inside valve box 94 depending on the pressure difference above and below ball 97. When the pressure below ball 97 is greater, ball 97 rises and blocks hole 95a, preventing backflow of resin material. When the pressure above ball 97 is greater, ball 97 descends and allows forward flow. Even if ball 97 descends to its maximum and blocks hole 96a, resin material will flow through sub-hole 96b, maintaining forward flow. The same is true for second check valve 93R.

[0078] For some reason, the resin material may flow from the first diagonal flow path 85 to the second diagonal flow path 87. When this happens, the second check valve 93R is closed to prevent backflow. Similarly, the resin material may flow from the second diagonal flow path 87 to the first diagonal flow path 85. When this happens, the first check valve 93L is closed to prevent backflow.

[0079] Although the first screw rotation mechanism 56L and the second screw rotation mechanism 56R are hydraulic motors, they may be electric motors or electric motors with reducers.

[0080] Furthermore, the engaging portion 36 may be a rough surface, a step, or a recess formed on the outer periphery of the tie bar 31, in addition to the sawtooth portion, and is not limited to a sawtooth shape.

[0081] The present invention is suitable for a vertical injection molding apparatus that includes a mold clamping unit with a vertical mold clamping shaft and an injection unit that is disposed vertically above the mold clamping unit.

[0082] 10...vertical injection molding apparatus, 12...mold, 13...lower mold, 14...upper mold, 17...product removal position, 18...mold clamping position, 20...mold clamping device, 20a...mold clamping shaft, 21...bed, 22...pressure receiving platen, 23...turntable, 24...half nut position adjustment mechanism, 25...mold clamping mechanism, 26...half nut, 27...mold opening and closing mechanism, 28...movable platen, 31...tie bar, 31a...lower end of tie bar, 36...engagement portion (serrated portion), 50...injection device, 50a...injection shaft, 53a...nozzle, 53L...first heating barrel, 53R...second heating barrel, 79...traction platen, 80...Y-shaped adapter, 81...V-shaped portion, 82...I-shaped portion, 85...first diagonal flow path, 87...second diagonal flow path, 88...downward extension line.

Claims

1. A vertical injection molding apparatus comprising: a clamping device with a vertical clamping axis that clamps an upper mold to a lower mold; a turntable on which the lower mold is placed and which moves between a clamping position and a product removal position; and an injection device with a vertical injection axis that is positioned above the clamping device and injects a resin material into a mold consisting of the lower mold and the upper mold, wherein the injection device has a pair of left and right first and second heater barrels, and a Y-shaped adapter connected below the first and second heater barrels to join the resin material from the first heater barrel and the resin material from the second heater barrel and inject it from a single nozzle.

2. A vertical injection molding apparatus as claimed in claim 1, wherein the Y-shaped adapter comprises a V-shaped section connected below the first heating barrel and the second heating barrel, and an I-shaped section detachably connected to the V-shaped section and including the nozzle, the V-shaped section having a first diagonal flow path and a second diagonal flow path, and a downward extension line extending downward from the first diagonal flow path and the second diagonal flow path does not interfere with the wall of the V-shaped section.

3. A vertical injection molding apparatus as claimed in claim 1 or 2, wherein the mold clamping device comprises a pressure-receiving platen fixed to a bed, a traction platen arranged below the pressure-receiving platen and raised and lowered by a half nut position adjustment mechanism, a movable platen arranged above the pressure-receiving platen and raised and lowered by a mold opening and closing mechanism, and a tie bar lowered from the movable platen and passing through the pressure-receiving platen and the traction platen, and clamps the mold arranged between the pressure-receiving platen and the movable platen, wherein an engagement portion is provided at the lower end of the tie bar, and a half nut that engages with the engagement portion is provided below the traction platen.

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