Rotary injection molding machine and rotary injection molding machine operation method

Abstract

To provide a technology allowing a rotary injection molding machine to be compact.SOLUTION: A rotary injection molding machine comprises: a mold clamping device having a lower fixed platen on which a fixed mold can be mounted, an upper movable platen which is positioned above the lower fixed platen and has a rotary table on its lower surface and on which a movable mold can be mounted via the rotary table, a mold opening / closing mechanism which opens and closes the fixed mold and the movable mold by raising and lowering the upper movable platen, a mold clamping cylinder which is provided on the lower fixed platen and clamps the fixed mold and the movable mold by pulling a rod that functions as a tie bar for guiding the raising and lowering of the upper movable platen, and a coupling part which is provided on the upper movable platen and connects the rod to the upper movable platen to transmit the mold clamping force of the mold clamping cylinder to the movable mold; and an injection device for injecting molding material into the cavity formed between the fixed mold and the movable mold.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a technique for obtaining molded articles, particularly composite molded articles such as multi-color molded articles and multi-layer molded articles using a plurality of colors or a plurality of types of resins, by injection molding. [Background technology]

[0002] A known example of this type of technology is a vertical rotary injection molding machine described in Patent Document 1. This injection molding machine includes a fixed platen arranged horizontally, a movable platen installed opposite the fixed platen and movable up and down to change its position relative to the fixed platen, a vertical drive mechanism that drives the movable platen in the vertical direction, a rotary table that is installed on the underside of the movable platen so as to be movable up and down together with the movable platen and that can rotate forward and backward along the circumferential direction, a servo motor drive mechanism that drives the rotary table in the forward and reverse directions, and a rotation angle detection means that detects the rotation angle of the rotary table from a set reference position, and relates to a vertical rotary injection molding machine that can simultaneously clamp multiple sets of molds, each consisting of multiple lower molds installed on the fixed platen and multiple upper molds installed on the rotary table opposite the lower molds, at multiple rotation positions of the rotary table. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 6-91688 Summary of the Invention [Problem to be solved by the invention]

[0004] The problem to be solved by the embodiments of the present invention is to provide a technology that can make a rotary injection molding machine compact. Other problems and novel features will become apparent from the description of this specification and the accompanying drawings. [Means for solving the problem]

[0005] A rotary injection molding machine according to one embodiment is characterized by comprising: a lower fixed platen to which a fixed mold can be attached; an upper movable platen located above the lower fixed platen and having a rotary platen on its underside, to which a movable mold can be attached via the rotary platen; a mold opening and closing mechanism that opens and closes the fixed mold and the movable mold by raising and lowering the upper movable platen; a clamping cylinder that is provided on the lower fixed platen and clamps the fixed mold and the movable mold by pulling a rod that functions as a tie bar that guides the raising and lowering of the upper movable platen; a clamping device that has a connecting portion that is provided on the upper movable platen and connects the rod to the upper movable platen to transmit the clamping force of the clamping cylinder to the movable mold; and an injection device that injects molding material into a cavity formed between the fixed mold and the movable mold. [Brief explanation of the drawings]

[0006] [Figure 1] 1 is a block diagram showing the configuration of a rotary injection molding machine according to a first embodiment. [Figure 2] 1 is a schematic front view showing a configuration of a rotary injection molding machine according to a first embodiment. [Figure 3] FIG. 3 is a view taken along the line AA in FIG. 2. [Figure 4] FIG. 3 is a view taken along the line BB in FIG. 2. [Figure 5] FIG. 3 is a cross-sectional view illustrating the configuration of a first flange and a second flange. [Figure 6] FIG. 2 is a schematic front view showing the configuration of the stopper device. [Figure 7] FIG. 10 is a schematic front view showing the configuration of a rotary injection molding machine according to a second embodiment. [Figure 8] FIG. 10 is a schematic front view showing the configuration of a rotary injection molding machine according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiments. For clarity of explanation, the following description and drawings have been appropriately simplified. In each drawing, the same elements are given the same reference numerals, and duplicate explanations are omitted as necessary. Furthermore, hatching has been omitted in some areas to avoid cluttering the drawings.

[0008] First Embodiment (Device configuration) The overall configuration of a rotary injection molding machine according to this embodiment will now be described. Fig. 1 is a block diagram showing the configuration of a rotary injection molding machine 1 according to this embodiment.

[0009] 1, a rotary injection molding machine 1 according to this embodiment includes two injection units 10A and 10B, a mold clamping unit 20, and a control unit 30 that drives and controls the injection units 10A and 10B and the mold clamping unit 20. When there is no need to distinguish between the injection units 10A and 10B, the injection units will be referred to as injection unit 10 in the following description.

[0010] The injection unit 10 has a heating cylinder, a screw, and the like, and is located adjacent to a clamping unit 20 to which a mold corresponding to the injection unit 10 is attached, as will be described in detail later. The injection unit 10 rotates the screw to melt and knead resin pellets fed into a hopper connected to the heating cylinder, and then advances the screw to inject the molten resin (molding material) into a mold through a nozzle, thereby obtaining a desired resin molded product. The rotary injection molding machine 1 according to this embodiment obtains, as a resin molded product, a multi-material molded product made of, for example, two colors or two different materials. Therefore, in this embodiment, the resin pellets fed into the injection units 10A and 10B are different in color, material, etc.

[0011] The control device 30 is connected to the injection device 10, the mold clamping device 20, and the like, and controls these devices. Specifically, it drives and controls various actuators provided in the injection device 10 and the mold clamping device 20. It is also connected to switches such as limit switches and sensors. The control device 30 has hardware such as a central processing unit (CPU), read-only memory (ROM), and random access memory (RAM), not shown, which cooperate to control the series of device operations described above. The control device 30 may also have an input / output unit to receive input from a user and output the input via a display, for example, to input and display various settings for the rotary injection molding machine 1. The control device 30 may be incorporated into either the injection device 10A, 10B or the mold clamping device 20, or may be provided independently as an operation panel or control panel near the mold clamping device 20, or may be implemented as an information processing device such as a PC (personal computer).

[0012] Next, a detailed description will be given of the configuration of the rotary injection molding machine 1. Fig. 2 is a schematic front view showing the configuration of the rotary injection molding machine 1 according to this embodiment. Fig. 3 and Fig. 4 are views taken along the arrows AA and BB in Fig. 2, respectively.

[0013] As shown in FIG. 2, in the rotary injection molding machine 1 according to this embodiment, injection units 10A and 10B are provided on a floor F, which is an installation surface, so as to be able to move toward and away from a clamping unit 20 in directions (hereinafter referred to as left-right directions or sides as appropriate). The clamping unit 20 is disposed between injection units 10A and 10B, and each injection unit 10 has a nozzle facing toward the clamping unit 20 so as to be able to inject molten resin into a fixed mold 214 of the clamping unit 20, which will be described later. The clamping unit 20 includes a lower fixed platen 21, an upper movable platen 22, a rotary drive unit 23, a mold opening / closing mechanism 24, a clamping cylinder 25, half nuts 26, an adjustment mechanism 27, and a stopper unit 28. The configuration of the clamping unit 20 will be described in detail below.

[0014] (Lower fixed plate 21) As shown in FIGS. 2 and 3 , the lower fixed platen 21 is formed in a rectangular shape with a predetermined thickness. The lower fixed platen 21 has four corners on its lower surface placed on a floor surface F via installation structural members 212. In other words, the installation structural members 212 are detachably provided to define a predetermined space between the lower fixed platen 21 and the floor surface F. Note that the installation structural members 212 may have legs integrally formed with the lower fixed platen 21 by, for example, casting. The upper surface of the lower fixed platen 21 serves as a mold mounting surface, and two fixed molds 214 are mountable on this upper surface. Specifically, one guide 216 is provided on the upper surface of the lower fixed platen 21 corresponding to one fixed mold 214. Furthermore, a plurality of clamper devices 218, such as four clamper devices 218 corresponding to one fixed mold 214, are provided on mold mounting portions located approximately in the center of the upper surface of the lower fixed platen 21. The fixed molds 214 are fixed to the lower fixed platen 21 by the clamper devices 218. The fixed mold 214 is formed so as to be able to mate with a movable mold 222 attached to a rotary platen 224, which will be described later, the lower surface of which serves as a mold mounting surface. A mold mounting platen may be provided on the upper surface of the lower fixed platen 21, including a first flange 256, which will be described later in detail, and the clamper device 218 and the like may be provided on this mold mounting platen.

[0015] The height from the floor F of the upper surface of the lower fixed platen 21 (the platen surface excluding protrusions such as the clamper device 218) is, for example, preferably 0.9 m or more and 2.0 m or less, and more preferably 1.0 m or more and 1.6 m or less. For example, if the upper surface is designed to exceed the upper limit of this range, the height of the mold exchange cart and the like will become excessively high, and it will be difficult for workers to visually check the platen surface. On the other hand, if the upper surface is designed below the lower limit of this range, problems will arise, such as difficulty in storing the clamping cylinder 25 (described later) inside the lower fixed platen 21 and in maintenance.

[0016] The mold exchange cart is provided in a mold exchange device (not shown) used for mold exchange in the mold clamping unit 20, and can move horizontally on the base of the mold exchange device with a mold set of a fixed mold 214 and a movable mold 222 (described later) mounted thereon. During mold exchange, the mold set on the mold exchange cart is sent to a mold mounting section located approximately in the center of the lower fixed platen 21 via a guide 216 by the mold exchange mechanism. Thereafter, the fixed mold 214 is fixed by a clamper device 218, and the movable mold 222 is fixed by a clamper device 225 (see FIG. 4 ) provided on the rotary platen 224. By designing the lower fixed platen 21 so that the height of its upper surface falls within the above-mentioned numerical range, it is possible to make the height of the upper surface of an existing mold exchange cart approximately the same as that of the lower fixed platen 21, or to reduce the height of the mold exchange cart. Therefore, keeping the height of the upper surface of the lower fixed platen 21 within an appropriate range is itself a useful effect.

[0017] (Upper movable plate 22) 2 and 4, in the mold clamping unit 20, the upper movable platen 22 is located above the lower fixed platen 21 and is formed in a rectangular shape with a predetermined thickness. The upper movable platen 22 has insertion holes formed near each of the four corners in a plane perpendicular to the up-down direction (mold opening / closing direction), through which a rod 251 (described later) of the mold clamping cylinder 25 can be inserted. In this embodiment, the rod 251 is configured as a tie bar, and by inserting the rod 251 into the insertion hole, the upper movable platen 22 is guided by the rod 251 and can be raised and lowered by the mold opening and closing mechanism 24 so as to move closer to or away from the lower fixed platen 21 in the up-down direction.

[0018] An electric motor such as a servo motor or a ball screw mechanism, which serves as a drive unit for an ejector device (not shown), is provided on the upper surface of the upper movable platen 22. The drive unit for the ejector device may be a drive unit that uses fluid pressure such as hydraulic pressure. Note that the location where the ejector device is provided is not limited to this, and may be inside the movable mold 222, the lower fixed platen 21 side, or the fixed mold 214.

[0019] A rotary platen 224 is rotatably provided on the lower surface of the upper movable platen 22. The rotary platen 224 has a mold mounting surface on the lower surface of which the two movable molds 222 described above are mounted. In other words, the upper movable platen 22 is provided so that the movable mold 222 can be mounted thereon. The rotary platen 224 is formed in a disk shape with a predetermined thickness, and has a rotation shaft 226 fixed thereto that is parallel to the vertical direction. The rotation shaft 226 is journaled by a bearing at approximately the center of the upper movable platen 22, so that the rotary platen 224 can rotate relative to the upper movable platen 22.

[0020] The rotary platen 224 is driven to rotate by a rotary drive device 23 that can be controlled by the control device 30. Specifically, the rotary drive device 23 includes a power source 232, such as a servo motor, provided on the front side of the upper movable platen 22, a toothed pulley 234 that is connected to the power source 232 and rotates, and a belt 236 that is wound around the toothed pulley 234 and the rotary platen 224 and has teeth formed on its inner circumferential surface that mesh with the toothed pulley 234. Teeth (not shown) are formed on the outer circumferential surface of the rotary platen 224, and the teeth of the belt 236 also mesh with these teeth. Therefore, the belt 236 can be moved circumferentially in conjunction with the rotation of the toothed pulley 234 by the power source 232, and the rotary platen 224 can be rotated around the rotation axis 226, more specifically, through a range of at least 180 degrees. In this embodiment, in order to ensure that the tooth profile formed on the inner surface of the belt 236 meshes with the teeth of the rotary platen 224 and the toothed pulley 234, a driven wheel (so-called idler) 238 that applies tension to the belt 236 is provided on the underside of the upper movable platen 22 so as to be rotatable relative to the belt 236 around an axis facing in the vertical direction.

[0021] As described above, the clamper device 225 for attaching the movable mold 222 is provided on the lower surface of the rotary platen 224 at a position corresponding to the clamper device 218 of the lower fixed platen 21. If necessary, a stopper for preventing the movable mold 222 from falling may be provided on the rotary platen 224.

[0022] The shape of the rotary platen 224 is not limited to a disk shape, and may be formed into other shapes such as a rectangular plate shape depending on the shape of the movable mold 222 to be attached. Also, a mold attachment plate that protrudes from the rotary platen 224 may be attached to the rotary platen 224, and the movable mold 222 may be attached to this mold attachment plate.

[0023] Furthermore, the means for rotationally driving the rotary platen 224 is not limited to the rotation drive device 23. For example, a gear or pulley connected to the rotation shaft 226 may be provided on the upper movable platen 22, and a gear or pulley of the power source 232 may be disposed on the upper surface side of the upper movable platen 22, with a belt wound between the two gears or pulleys. Also, a gear may be provided on the outer circumferential surface of the rotary platen 224 or on the rotation shaft 226, and the gear of the power source 232 may be directly meshed with this gear.

[0024] In this embodiment, as described above, two fixed molds 214 are attached to the lower fixed platen 21, and two movable molds 222 are attached to the upper movable platen 22. The cavity surfaces of the two movable molds 222 have the same shape, but the cavity surfaces of the two fixed molds 214 have different shapes. The temperature of the molding mold (mold set) consisting of the fixed mold 214 and the movable mold 222 is controlled by a temperature control device (not shown). In FIG. 2, the fixed mold 214 and the movable mold 222 are in contact with each other and are mated, i.e., in a mold closed state. When the fixed mold 214 and the movable mold 222 are closed in this manner, a primary cavity and a secondary cavity are defined between the respective molds. In this embodiment, the number of molding molds attached to the mold clamping unit 20 is two, but the number is not limited to one to four. Furthermore, one molding mold may have two or more cavities. Here, the side surfaces of the fixed mold 214 each serve as a nozzle touch surface, and the nozzle of the injection unit 10 abuts against the nozzle touch surface. A hot runner is provided between the nozzle touch surface and the cavity, and the molten resin injected from the nozzle is sent to the cavity via the hot runner.

[0025] (Mold opening / closing mechanism 24) 2 to 4, the mold opening and closing mechanisms 24 move the upper movable platen 22 up and down relative to the lower fixed platen 21, and are provided on each of the side surfaces (surfaces perpendicular to the left-right direction) near the four corners of the lower fixed platen 21 and the upper movable platen 22 in a plane perpendicular to the up-down direction, i.e., four mold opening and closing mechanisms 24 are provided in total. Each of these four mold opening and closing mechanisms 24 includes: a ball screw nut 241 that is immovably held by a bracket provided on the side surface of the upper movable platen 22 and functions as a connecting member that connects the upper movable platen 22 to the upper movable platen 22 so as not to rotate relatively; a ball screw 242 that is provided on a bracket provided on the side surface of the lower fixed platen 21 and functions as a rotating member that is screwed onto and inserted through the ball screw nut 241 so as to be rotatable relatively; and a drive source 244 that functions as a rotation drive unit such as a servo motor and is fixed by a bracket 243 provided on the side surface of the lower fixed platen 21. A drive pulley 245 is provided on the drive shaft of the drive source 244, and a driven pulley 246 is provided on the ball screw 242. An endless timing belt 247 is stretched between the drive pulley 245 and the driven pulley 246. Therefore, the rotation of the drive shaft of the drive source 244 is transmitted to the ball screw 242 via the timing belt 247 and the driven pulley 246. In other words, either the ball screw nut 241 or the ball screw 242 may be provided rotatable with respect to either the lower fixed platen 21 or the upper movable platen 22.

[0026] When the ball screw 242 is rotated by the drive source 244, the upper movable platen 22 moves up and down relative to the lower fixed platen 21 while being guided by a rod 251 (described later). The servo motor of the drive source 244 has a rotary encoder that detects the rotation angle, and the vertical position of the upper movable platen 22 relative to the lower fixed platen 21 can be detected by the rotary encoder. The drive source 244 is connected to the control device 30 and is controllable. The drive source 244 is preferably an electric motor having a fail-safe function, in particular, a servo motor with an electromagnetic brake that can be equipped with an electromagnetic brake that can be activated in the event of a power outage. By using an electric motor as the drive source 244, at least one of energy saving effects, faster speed and higher precision of mold opening / closing control of the upper movable platen 22 can be expected compared to a drive device using fluid pressure, etc.

[0027] The electromagnetic brake is a non-excitation type electromagnetic brake that can prevent the rotation of the drive source 244, i.e., the drive shaft of the servo motor and the drive shaft of the ball screw 242 via the timing belt 247, even during a power outage. The electromagnetic brake can also prevent the rotation of the drive shaft by a signal during abnormal conditions other than a power outage. The signal can be sent, for example, by the control device 30. In this embodiment, each of the four mold opening and closing mechanisms 24 is equipped with a drive source 244. Therefore, even if the electromagnetic brake of one drive source 244 fails, the remaining three electromagnetic brakes can prevent the upper movable platen 22 from descending. Although the stopper device 28, which is a mechanical safety mechanism, operates separately, the above-mentioned brake operates without relying on it. Regarding the electromagnetic brake, the drive shaft of the ball screw 242 can also be prevented from rotating by attaching an electromagnetic brake separate from the drive source 244 to the side of the ball screw 242. An example of attaching an electromagnetic brake separate from the drive source 244 to the side of the ball screw 242 is to fix an electromagnetic brake through which the ball screw 242 is inserted to the lower fixed platen 21. By providing an electromagnetic brake on the side of the ball screw 242, even if the timing belt 247 connecting the drive pulley 245 of the drive source 244 and the driven pulley 246 of the ball screw 242 breaks while the ball screw 242 is rotating, the rotation of the ball screw 242 can be reliably stopped.

[0028] As a modification of the case where an electromagnetic brake is attached to the drive shaft of ball screw 242, a brake that acts in the event of an abnormality such as a power outage may be attached to driven pulley 246. In this case, brake teeth may be inserted into the gear portion on the circumferential surface of driven pulley 246, or two brakes provided on the upper and lower surfaces of driven pulley 246 may press driven pulley 246 from both the top and bottom.

[0029] The mold opening and closing mechanism 24 is preferably provided at a position relative to the lower fixed platen 21 where it will not be interfered with by the mold exchange carriage or mold exchange mechanism of the mold exchange device and will not be affected when the injection units 10 provided on both sides of the mold clamping unit 20 move forward or backward. It is also preferable that the drive source 244 and ball screw 242 of the mold opening and closing mechanism 24 be provided at a position where they are less susceptible to the influence of radiant heat from the heating cylinder and nozzle of the injection unit 10, or that a shielding plate or the like be provided between the injection unit 10 and the drive source 244 or ball screw 242 to reduce the influence of radiant heat.

[0030] The mold opening and closing mechanism 24 may be connected in any manner as long as the upper movable platen 22 can move in the vertical direction. For example, a direct drive system may be used in which the ball screw 242 is directly attached to the drive shaft of the drive source 244, or a system in which one ball screw 242 is rotated by multiple drive sources 244. Furthermore, a ball screw nut 241 rotated by the drive source 244 and the ball screw 242 may be provided on the upper movable platen 22 as a rotating member, and the ball screw 242 may be connected to the lower fixed platen 21 as a connecting member so as not to rotate relative to the lower fixed platen 21. The mold opening and closing mechanism 24 may at least partially use a feed screw mechanism or a rack and pinion mechanism other than a ball screw, and the actuators for these mechanisms are not limited to electric motors such as servo motors, but may also use fluid pressure cylinders that use fluid pressure such as hydraulic pressure. The number of mold opening and closing mechanisms 24 is not limited to four, and may be two or more.

[0031] (Mold clamping cylinder 25) As shown in FIGS. 2 to 4, the clamping cylinders 25 are built into the lower fixed platen 21 near each of its four corners in a plane perpendicular to the vertical direction. Each of these four clamping cylinders 25 supports a cylindrical rod 251, whose axis faces the vertical direction, so that it can move up and down. The rod 251 is inserted near the four corners of the upper movable platen 22 and serves as a tie bar to guide the movement of the upper movable platen 22. The clamping cylinder 25 is hydraulically operated to pull the rod 251, thereby clamping the molding die in a closed state. The clamping cylinder 25 defines a cylinder chamber 252 between itself and a cylinder tube surrounding the rod 251. The cylinder tube may be separate from the lower fixed platen 21, or may be configured integrally with the lower fixed platen 21. A piston 253 is provided below the rod 251, and the piston 253 is slidably inserted into the cylinder chamber 252.

[0032] The cylinder chamber 252 has a mold clamping oil chamber 254A formed on the upper side across the piston 253, into which hydraulic oil flows during mold clamping, and a powerful mold opening oil chamber 254B formed on the lower side, into which hydraulic oil flows during mold release. Two pipes (not shown) are individually connected to the mold clamping oil chamber 254A and the powerful mold opening oil chamber 254B. Each pipe is fitted with a pressure sensor (not shown) that measures the pressure of the hydraulic oil, and is also connected to a directional switching valve such as a servo valve or a cartridge valve (not shown). The mold clamping cylinder 25 is connected to the above valves, as well as other valves, pumps, and tanks that constitute a hydraulic system (not shown), and can be controlled together with the hydraulic system by the control device 30.

[0033] The hydraulic device is disposed on the floor surface F around the mold clamping unit 20. The hydraulic device supplies hydraulic oil not only to the above-mentioned mold clamping cylinder 25 but also to the adjustment mechanism 27, the clamper devices 218, 225, etc., which will be described in detail later. The hydraulic device also supplies hydraulic oil to the forward and backward movement of the injection unit 10 in the left and right directions and to the cylinder of the stopper device 28, which will be described in detail later, when these are hydraulically operated. In this embodiment, the mold clamping cylinder 25 is provided on the lower fixed platen 21. Therefore, the above-mentioned piping distance of the hydraulic device can be shortened and the amount of hydraulic oil can be reduced, which in turn enables cost reduction.

[0034] The lower end of the rod 251 protrudes downward beyond the piston 253, and the bottom surface is detachably connected to a mounting plate 272 of the adjustment mechanism 27, which will be described in detail later. The diameter of the protruding portion of the rod 251 is smaller than the diameter of the portion located above the piston 253.

[0035] (Half nut 26) As shown in FIG. 2 , a total of four half nuts 26 are provided on the upper surface of the upper movable platen 22 so as to be adjacent to the rods 251 inserted through the insertion holes near the four corners of the upper surface of the upper movable platen 22. The half nuts 26 function as coupling parts that couple the corresponding adjacent rods 251 to the upper movable platen 22 in order to transmit the clamping force of the clamping cylinder 25 to the movable mold 222. That is, the half nuts 25 serving as coupling parts are provided on the upper movable platen 22 and couple the rods 251 to the movable platen 22 in order to transmit the clamping force of the clamping cylinder 25 to the movable mold 222. The half nuts 26 are made up of a pair of half nut blocks. The half nut blocks have a plurality of teeth that are evenly spaced apart in the vertical direction on the surface facing the rods 251. A plurality of annular fitting grooves 255 are formed at equal intervals along the vertical direction on a portion of the circumferential surface of the upper side of each of the four rods 251. The fitting grooves 255 can fit (be coupled) with the teeth of the corresponding half nuts 26. The axial length of the rods 251 in the half nuts 26 is set shorter than the axial length of the region of the rod 251 where the fitting grooves 255 are formed. Each half nut 26 is connected to a driving means such as a cylinder that is extended and retracted by hydraulic pressure or a ball screw mechanism that is driven forward and backward by an electric motor such as a servo motor. The half nuts 26 are driven forward and backward so that the teeth fit into and disengage from the fitting grooves 255 of the corresponding rod 251. The driving means drives the half nuts 26 at two locations, and therefore, two driving means are used in this embodiment. The vertical length of one tooth of each half nut 26 is shorter than the width of one fitting groove 266. Therefore, when the teeth of the half nuts 26 fit into the fitting grooves 255, a slight gap is created between them.

[0036] According to the structure using the half nuts 26, the stroke of the clamping cylinder can be shortened compared to a conventional clamping device using a hydraulic cylinder without half nuts, and the amount of hydraulic fluid, such as hydraulic oil, can be significantly reduced compared to conventional devices. Although the clamping cylinder 25 can be mounted on the upper movable platen 22, the weight of the half nuts 26 is significantly lighter than that of the clamping cylinder 25. Therefore, by mounting the clamping cylinder 25 on the lower fixed platen 21 and the half nuts 26 on the upper movable platen 22, the weight of the upper movable platen 22, including the rotary platen 224 and its rotation mechanism, can be reduced. This, combined with the electrification of the mold opening / closing mechanism 24, can reduce power consumption. Alternatively, the mold opening / closing movement of the upper movable platen 22 can be increased in speed. The half nuts 26 may be of a type that uses hydraulic or other fluid pressure to press a sleeve body against the rod 251 to lock it.

[0037] It is preferable that a sealing member be attached to the piston 253 to prevent leakage of the working fluid. The same applies to the rod 251 and the inner circumferential surface of the cylinder side of the clamping cylinder 25 that slides relative to the rod 251. These sealing members are made of resin, elastomer, or the like, and become worn with continuous molding every day, so they need to be replaced. In this embodiment, such replacement can be easily performed by removing the first and second flanges 256, 257 (see FIGS. 3 and 5) that are provided around the rod 251 in a manner that allows the rod 251 to pass through. A method for replacing the sealing members will be described later.

[0038] Fig. 5 is a cross-sectional view for explaining the configuration of the first and second flanges 256, 257. Fig. 5 schematically illustrates the structure of a region from the radial edge of the rod 251 to approximately the center of the first flange 256 cut in the vertical direction, with the cut surface viewed from the front side.

[0039] 2, 3, and 5, the first flange 256 is for closing the upper part of the mold clamping oil chamber 254A, and is formed in a ring shape with a predetermined thickness. The rod 251 is inserted into a through-hole 256A corresponding to the hollow part of the first flange 256, and is fitted to the lower fixed platen 21. The outer diameter of the first flange 256 is approximately the same as the outer diameter of the cylinder barrel of the mold clamping cylinder 25. The through-hole 256A of the first flange 256 is formed with a step so that the diameter on the upper side is expanded, and a seal member 258 and a cylindrical bushing 260, which will be described later, are inserted into the expanded diameter part.

[0040] The first flange 256 has a plurality of insertion holes formed from its upper surface to its lower surface at predetermined intervals along the circumferential direction of the first flange 256, through which bolts Bo1 are inserted. The cylinder barrel of the mold clamping cylinder 25, located below the first flange 256, has bolt holes formed at positions corresponding to the insertion holes in the first flange 256. That is, the first flange 256 is attached to the upper surface side of the lower fixed platen 21, which includes the cylinder barrel portion of the mold clamping cylinder 25. The bolts Bo1 are inserted through the insertion holes in the first flange 256 and screwed into the bolt holes in the cylinder barrel, thereby removably fixing the first flange 256 to the cylinder barrel via the bolts Bo1. Furthermore, the first flange 256 has a plurality of bolt holes 256B formed at predetermined intervals along the circumferential direction of the first flange 256, for fixing the second flange 257 to the first flange 256, at an edge portion near the through-hole 256A, radially inward of the insertion holes, i.e., near the through-hole 256A.

[0041] The second flange 257 is used to insert and secure a seal member 258 to be inserted between the first flange 256 and the rod 251. The second flange 257 is formed in a cylindrical shape with a predetermined thickness, and the rod 251 is inserted into a through-hole 257A corresponding to the hollow portion of the second flange 257 so as to contact the periphery of the second flange 257, with a portion of the second flange 257 being inserted into the through-hole 256A of the first flange 256. The second flange 257 has a smaller diameter than the first flange 256, and the diameter of the through-hole 257A and the outer diameter of the rod 251 are approximately the same. The second flange 257 has a small-diameter portion 257B to be inserted into the gap between the first flange 256 and the rod 251, and a large-diameter portion 257C to be fixed to the surface of the first flange 256. The lower tip of the small-diameter portion 257B serves as a pressing surface for pressing a cylindrical seal member 258 made of resin, elastomer, or the like into the through-hole 256A of the first flange 256.

[0042] A plurality of insertion holes 257D, through which bolts Bo2 are inserted, are formed in the large diameter portion 257C from its upper surface to its lower surface at predetermined intervals along the circumferential direction of the second flange 257. These insertion holes 257D are provided at positions corresponding to the bolt holes 256B of the first flange 256. Therefore, the bolts Bo2 can be inserted through the insertion holes of the second flange 257 and screwed into the bolt holes of the first flange 256. This screwing allows the second flange 257 to be detachably fixed to the first flange 256 via the bolts Bo2.

[0043] The seal member 258 is for liquid-tightly closing the mold clamping oil chamber 254A, and is formed in a cylindrical shape, with the rod 251 inserted into a through hole corresponding to the hollow portion of the seal member 258 so as to contact the periphery of the rod 251. The seal member 258 is preferably a V-packing made of resin, elastomer, or the like. Note that the reference numeral 259 shown in Fig. 5 denotes a washer.

[0044] Furthermore, no member equivalent to the first flange 256 is provided at the bottom of the mold clamping cylinder 25, but a member equivalent to the second flange 257 is detachably provided on the main body of the mold clamping cylinder 25. The method for inserting the seal member at the bottom of the mold clamping cylinder 25 will be explained in the same manner as the explanation for the second flange 257 and seal member 258 at the top of the mold clamping cylinder 25, and a detailed explanation will be omitted.

[0045] (Adjustment mechanism 27) The adjustment mechanism 27 adjusts the vertical position of the rod 251 by moving the rod 251 relative to the lower fixed platen 21. As described above, there is a gap between one tooth of the half nut 26 and the groove width of one fitting groove 255 of the rod 251. Therefore, the vertical position of the rod 251 relative to the upper movable platen 22 is displaced before and after the mold clamping operation during molding and the powerful mold clamping operation. Alternatively, if the mold thickness of the molds such as the fixed mold 214 and the movable mold 222 differs from the set thickness, it is necessary to adjust the position of the rod 251 when the molds are closed. The adjustment mechanism 27 is used to adjust the position of the rod 251 in such cases.

[0046] 2 and 3, a space is defined between the lower surface of the lower fixed platen 21 and the floor surface F on which the clamping unit 20 is installed. At least a portion of the adjustment mechanism 27 is provided in this space. The adjustment mechanism 27 is provided detachably relative to the rod 251. Specifically, the adjustment mechanisms 27 are provided in pairs at the four corners of the lower fixed platen 21 in a plane perpendicular to the up-down direction, with each of the four corners sandwiched between the corners, i.e., a total of eight adjustment mechanisms 27 are provided. One of the pair of adjustment mechanisms 27 is provided on a side of the lower fixed platen 21, and the other is provided on the front or back of the lower fixed platen 21, and both are positioned parallel to the clamping cylinder 25 in the horizontal direction. Therefore, compared to when the adjustment mechanisms are provided in series with the clamping cylinder 25 in the up-down direction, the vertical width of the lower fixed platen 21 can be narrowed, and the height of the clamping unit 20 can be reduced.

[0047] In this embodiment, the adjustment mechanism 27 is a hydraulic cylinder, and is attached to the lower fixed platen 21 so that its rod faces downward. A mounting plate 272 is detachably connected to the lower end of the rod of the adjustment mechanism 27. The mounting plate 272 is a rectangular plate-shaped member, and the lower end of the rod 251 of the mold clamping cylinder 25 is detachably connected to the upper surface of the mounting plate 272, approximately at the center in the longitudinal direction. Both longitudinal ends of the mounting plate 272 protrude horizontally from the lower fixed platen 21, and the lower end of the rod of the adjustment mechanism 27 is connected to the upper surface of the protruding portion, as described above. In this way, the rod 251, mounting plate 272, and adjustment mechanism 27 are detachably connected to each other, and therefore, during maintenance, this connection can be released and they can be handled individually.

[0048] The vertical position of the rod 251 is adjusted by vertically moving the rod of the adjustment mechanism 27 back and forth, and this forward and backward movement is transmitted to the rod 251 via the mounting plate 272. The adjustment mechanism 27 is connected to the hydraulic device (not shown) described above, and therefore can be controlled by the control device 30.

[0049] In this embodiment, a rod cylinder or the like is used for the adjustment mechanism 27, but an electric motor such as an electric servo motor may also be used. Also, the adjustment mechanism 27 may be a rod movement oil chamber provided in the lower fixed platen 21 separately from the mold clamping oil chamber 254A and the powerful mold opening oil chamber 254B of the mold clamping cylinder 25. Furthermore, a rod holder may be provided on the upper end side of the rod 251 (above the upper movable platen 22), and the adjustment mechanism 27 may be provided on the rod holder.

[0050] (Stopper device 28) Fig. 6 is a schematic front view showing the configuration of the stopper device 28. In Fig. 6, only a cylinder 285 (described later) is shown in cross section, with its internal structure exposed. The stopper device 28 is a fall prevention mechanism that mechanically prevents the upper movable platen 22 from falling unintentionally, while the drive source 244 has an electromagnetic brake and electrically prevents the upper movable platen 22 from falling unintentionally. As shown in Figs. 2 to 6, the stopper device 28 has a safety bar 281 and a stopper 282.

[0051] The safety bar 281 is a long member that extends vertically from the upper surface of a protrusion (see FIG. 3 ) that protrudes from the front side of the lower fixed platen 21. A number of grooves 283 are formed at regular intervals in the vertical direction on the side surface of one of the left and right sides of the safety bar 281 (here, the injection unit 10B side). The grooves 283 are formed to be recessed toward the other left and right side. If the most recessed surface, i.e., the vertical surface, is defined as the bottom surface, and the two surfaces spaced apart vertically across the bottom surface are defined as the lower and upper surfaces, the lower surface is formed as a horizontal surface, and the upper surface is formed as an inclined surface that slopes downward toward the bottom surface. Therefore, the shape of the safety bar 281 can also be described as a sawtooth shape. The safety bar 281 has a plurality of grooves 283 formed vertically so as to encompass the range from the position of the stopper 282 when the upper movable platen 22 is fully raised due to mold opening to the position of the stopper 282 when the upper movable platen 22 is fully lowered due to mold closing. Therefore, the stopper 282 can be inserted into the groove 283 regardless of the intermediate position of the upper movable platen 22.

[0052] The stopper 282 of the stopper device 28 is a rectangular column member and is housed in a case 290 fixed to the lower surface of a bracket 284 fixed to the side or lower surface of the upper movable platen 22. A cylinder 285 is fixed to the rear end of the case 290. The cylinder 285 is operated by a fluid such as air or hydraulic pressure and has a fail-safe function. A piston 286 is provided within the cylinder 285 so as to be slidable in the left-right direction, and a rod 287 is provided on the opening side of the cylinder 285 relative to the piston 286 (hereinafter, the opening side will be referred to as the front end side, and the opposite side will be referred to as the rear end side). The rear end of the rod 287 is connected to the piston 286, and the front end side is connected to the stopper 282. The lower surface of the stopper 282 forms an abutment surface 282A that abuts against the lower surface of one of the multiple grooves 283 in the safety bar 281 when the upper movable platen 22 begins to descend undesirably due to various factors. In other words, the lower surface of the groove 283 functions as a locking surface that locks the stopper 282.

[0053] The lower surface, i.e., the abutment surface 282A, and the upper surface of the stopper 282 are guided by guides (not shown) provided on the upper movable platen 22. When an undesired downward movement occurs and the stopper 282 is locked by the safety bar 281, the guides allow the weight of the upper movable platen 22 to be supported by the stopper 282. A rod chamber 288 is formed around the rod 287 in the cylinder 285, to which a fluid such as air or hydraulic pressure is supplied from a drive source (for example, the hydraulic device described above). A resilient body, preferably a spring 289, is provided in the space on the rear end side of the piston 286 to bias the piston 286 and the rod 287 toward the tip end. Therefore, the cylinder 285 is a single-acting cylinder in which the rod 287 is only moved backward by supplying fluid to the rod chamber 288. Therefore, when the upper movable platen 22 is raised, fluid is supplied to the rod chamber 288, and the stopper 282 moves away from the safety bar 281.

[0054] During molding, a valve (not shown) is switched by a solenoid, and fluid is supplied to a rod chamber 288 of a cylinder 285. This causes the piston 286 to move backward against the biasing force of a spring 289, and at the same time, the stopper 282 also moves backward. As a result, the locking surface of the safety bar 281 and the stopper 282 do not interfere with each other, and the upper movable platen 22 can be freely raised and lowered by the operation of the mold opening and closing mechanism 24.

[0055] On the other hand, in the event of an abnormality, the solenoid of the valve (not shown) stops working, the valve is switched by a spring inside the valve, and the fluid in the rod chamber 288 is discharged to the drain. As a result, the piston 286 and rod 287 are pressed by the spring 289 and move toward the tip end, and at the same time, the stopper 282 fixed to the rod 287 moves forward and is inserted into the groove 283 of the safety bar 281, and the abutment surface 282A of the stopper 282 abuts against the locking surface, which is the lower surface of the safety bar 281. As a result, even if the upper movable platen 22 begins to descend undesirably, the descent is immediately stopped.

[0056] Note that when the stopper 282 advances, there may be cases where the tip of the stopper 282 first abuts against a portion of the safety bar 281 other than the groove portion 283 or against the inclined surface that is the upper surface of the groove portion 283. However, as the upper movable platen 22 descends, the stopper 282 advances to the bottom surface of the groove portion 283 while sliding on the inclined surface of the groove portion 283, and eventually the abutment surface 282A that is the lower surface of the stopper 282 abuts against the locking surface that is the lower surface of the groove portion 283. The above abnormality may also include a power outage. In that case, the solenoid of the valve stops working when the power is turned off, the valve is switched by the spring, the pressure in the rod chamber 288 is released, and the stopper 282 advances due to the biasing force of the spring 289. In addition, when the safety door is opened by an operator, a cam provided on the safety door mechanically presses the switch of the switch-equipped valve to activate the cylinder 285 and move the piston 286 forward, and / or the cam directly and mechanically moves the stopper 282, thereby advancing the stopper 282 toward the groove 283 of the safety bar 281, and preventing the upper movable platen 22 from descending undesirably.

[0057] Furthermore, the stopper device 28 may operate the cylinder 285 to stop the retraction of the piston 286 so that the stopper 282 is always inserted into one of the grooves 283 of the safety bar 281 when the upper movable platen 22 completes mold opening. In this case, it is desirable that the upper movable platen 22 is stopped at a height where the groove 283 of the safety bar 281 and the position of the stopper device 28 approximately coincide with each other as the mold opening completion position of the upper movable platen 22. Furthermore, instead of using the safety bar 281, the descent of the upper movable platen 22 can also be stopped by advancing the stopper 282 or the half nut 26 relative to the fitting groove 255 of the rod 251. In this case, it is desirable that the fitting groove 255 of the rod 251 be provided over the entire mold opening / closing stroke of the upper movable platen 22. Furthermore, the air cylinder or the like that operates the stopper 282 may be a center-closed three-way switching valve, and when the solenoid of the three-way valve is no longer activated due to a power outage or the like, the valve moves to the center of the neutral position by a spring or the like, and the supply of fluid such as air is stopped, as a result of which the stopper moves forward and prevents the upper movable platen 22 from falling.

[0058] Although it has been described that one safety bar 281 is provided on the lower fixed platen 21, it is preferable to determine the number of safety bars 281 based on the weight of the upper movable platen 22 and the strength of the safety bar 281. When providing multiple safety bars as necessary, multiple stoppers 282, cylinders 285, etc. may also be provided corresponding to the number of safety bars 281. Furthermore, the safety bar 281 may be provided on the front surface of the lower fixed platen 21 via a bracket or the like. In this case, the vertical length of the safety bar 281 can be shortened.

[0059] A take-out robot (not shown) may be provided near the mold clamping unit 20 (for example, on the front side in FIG. 2 ) other than where the injection unit 10 and the operation panel are provided. In this embodiment, when a molded product is molded, the molded product is held by the movable mold 222. The take-out robot can hold and take out the molded product that has been ejected by the ejector device provided on the upper movable platen 22. It is preferable that an interlock circuit be installed so that an operator cannot access the robot operation area while the take-out robot is operating.

[0060] (device operation) Next, the molding procedure for a molded product will be described as an operation method of the rotary injection molding machine 1 according to this embodiment. Here, the molding procedure will be described in order, starting from the mold open state, along with the molding of one final molded product. The main control unit described below is the control device 30. First, the upper movable platen 22 is lowered by rotating the ball screw 242 using the drive source 244 of the mold opening / closing mechanism 24, thereby closing the fixed mold 214 and the movable mold 222. This mold closing creates multiple cavities between the fixed mold 214 and the movable mold 222. After the cavities are created, the half nuts 26 provided on the upper movable platen 22 are actuated to engage the teeth of the half nut blocks of the half nuts 26 with the fitting grooves 255 of the rod 251, thereby connecting the half nuts 26 to the rod 251. After connection, hydraulic oil is supplied from the hydraulic device to the clamping oil chamber 254A of the clamping cylinder 25, and the rod 251 is pulled downward to perform mold clamping.

[0061] After the molds are clamped, injection unit 10A is already nozzle-touched to a first lower mold, which is one of two fixed molds 214. Molten resin is then injected into a primary molding cavity formed between the first lower mold and a first upper mold, which is one of two movable molds 222 corresponding to the first lower mold, using injection unit 10A. A cooling process is then performed after the injection, resulting in the formation of a primary molded product. Simultaneously or slightly after this, injection unit 10B, which is already nozzle-touched to a second lower mold, which is the other of two fixed molds 214, injects molten resin into a secondary molding cavity formed between the second lower mold and a second upper mold, which is the other of the two movable molds 222 corresponding to the second lower mold, to perform secondary molding. A cooling process is then performed after the secondary molding, resulting in the formation of a final molded product. Since the secondary molding cavity contains the primary molded product from the previous molding, the final molded product can be molded here.

[0062] After the cooling process is completed, hydraulic oil is supplied to the force-opening oil chamber 254B of the clamping cylinder 25 to release the movable mold 222 from the fixed mold 214. At this time, the primary molded product and the final molded product are held in the movable mold 222, respectively. Here, the primary molded product is held in the first upper mold, and the final molded product is held in the second upper mold. Note that force-opening by the clamping cylinder 25 is not always necessary. For example, for molded products and molds that require a small demolding force, demolding can be achieved using only the mold opening / closing mechanism 24, and force-opening is not required. After demolding, the half nuts 26 are actuated to disengage the teeth of the half nut block from the engagement groove 255, thereby releasing the connection between the half nuts 26 and the rod 251. After the release, the movable mold 222 is raised using only the mold opening / closing mechanism 24—that is, by reversely rotating the ball screw 242 using the drive source 244—until it reaches the mold-opening completion position. After the molds are opened, the final molded product is ejected by an ejector device provided on the upper movable platen 22. At this time, it is preferable to insert a take-out robot between the fixed mold 214 and the movable mold 222, and use the take-out robot to hold the final molded product and remove it from the rotary injection molding machine 1.

[0063] Furthermore, at the mold opening completion position, the rotary drive device 23 rotates the movable mold 222 together with the rotary platen 224 provided on the upper movable platen 22, and the first upper mold holding the primary molded product is moved to a position facing the second lower mold, opposite the first lower mold that molded the primary molded product. After the movement, the mold opening / closing mechanism 24 is used again to close the fixed mold 214 and the movable mold 222, forming multiple cavities. As described above, the primary molding cavities are also formed at the same time. In other words, the primary molding cavities are defined by the first lower mold and the second upper mold. After the mold is closed, the half nuts 26 are actuated to connect the half nuts 26 to the rod 251. After connection, the rod 251 is pulled downward by the clamping cylinder 25 to clamp the mold.

[0064] After the molds are closed, with the nozzle touching the second lower mold, injection unit 10B is used to inject molten resin into a secondary molding cavity formed between the first upper mold and the second lower mold, which contains the primary molded product, to perform secondary molding. A cooling process is performed after the secondary molding, to form the final molded product. At the same time, or slightly before or after this, with injection unit 10A already in nozzle touch with the first lower mold, injection unit 10A is used to inject molten resin into a primary molding cavity formed between the first lower mold and the second upper mold. A cooling process is performed after the injection, to form the primary molded product.

[0065] After the cooling process is completed, hydraulic oil is supplied to the powerful mold opening oil chamber 254B of the mold clamping cylinder 25 to release the movable mold 222 from the fixed mold 214. At this time, the primary molded product and the final molded product are held by the movable mold 222, respectively. After the release, the half nuts 26 are actuated to release the connection between the half nuts 26 and the rod 251. After the release, the movable mold 222 is opened to the mold opening completion position using only the mold opening / closing mechanism 24. After the mold is opened, the final molded product is ejected by an ejector device. At this time, a take-out robot may be inserted between the fixed mold 214 and the movable mold 222, and the take-out robot may hold the final molded product and remove it from the rotary injection molding machine 1. The above molding procedure is then repeated. An ejector device may be provided inside the fixed mold 214 to eject the final molded product from the fixed mold 214.

[0066] (Flange installation method) Next, a method for attaching the first and second flanges 256, 257 according to this embodiment will be described. First, with the rod 251 inserted through the through-hole 256A of the first flange 256, the first flange 256 is fixed to the upper surface of the cylinder of the mold clamping cylinder 25 with a bolt Bo1. Next, a seal member 258 is inserted between the rod 251 and the enlarged diameter portion of the first flange 256. After the insertion, with the rod 251 inserted through the through-hole 257A of the second flange 257, the small diameter portion 257B of the second flange 257 is inserted into the space between the enlarged diameter portion of the first flange 256 and the rod 251. Next, a bolt Bo2 is threaded into the bolt hole 256B of the first flange 256 via the through-hole 257A of the second flange 257, and these are bolted together. As a result of the above, the mold clamping oil chamber 254A of the mold clamping cylinder 25 is closed, and the gap between the rod 251 and the first and second flanges 256, 257 can be liquid-tightly sealed. The first and second flanges 256, 257 can be easily removed by reversing the procedure of this installation. Because the first and second flanges 256, 257 can be easily removed, it is also extremely easy to replace the seal member on the outer periphery of the piston 253 of the mold clamping cylinder 25.

[0067] (How to replace the seal) A method for replacing the seal member of the piston 253 described above will now be briefly described. First, the bolt Bo1 inserted through the first flange 256 is removed, and the piston 253 is lifted up together with the rod 251 by a crane. At this time, the first and second flanges 256, 257 are also lifted up together with the piston 253. After lifting, the seal member on the outer periphery of the piston 253 is replaced.

[0068] When replacement including replacement of the sealing member 258 is performed, the replacement is performed according to the following procedure. The replacement procedure differs depending on whether the sealing member 258 has a slit, such as a split oil seal, or is made up of multiple sealing members, or whether it is made up of a single ring-shaped member. In the former case, the sealing member 258 can be replaced after removing the second flange 257 from the first flange 256. On the other hand, in the latter case, there are two methods for replacement: one is to lift the upper movable platen 22 and the other is to remove the piston 253 from the rod 251.

[0069] In the method of lifting and replacing the upper movable platen 22, the upper movable platen 22 is lifted by a crane and pulled out from the rod 251, the second flange 257 is removed from the first flange 256, and the seal member 258 is replaced.

[0070] To remove the piston 253 from the rod 251, first, the bolt Bo1 is removed from the first flange 256 and the adjustment mechanism 27 is separated from the rod 251. Then, the piston 253 is lifted up together with the rod 251 by a crane. At this time, the first and second flanges 256, 257 are also pulled up together with the piston 253. Thereafter, the piston 253 and the first and second flanges 256, 257 are removed from the rod 251. After removal, the second flange 257 is removed from the first flange 256 by removing the bolt Bo2, and the seal member 258 is replaced. Note that various structures disassembled using the above method can be easily reassembled by following the steps in reverse.

[0071] According to the present embodiment described above, even when molding is performed using the rotary platen 224, the rotary platen 224 and the half nuts 26 are provided on the upper movable platen 22 side, and the clamping cylinder 25 is provided on the lower fixed platen 21, so the clamping device 20, and in turn the rotary injection molding machine 1, can be made compact without excessively increasing their size, particularly their vertical height. In addition, since the clamping cylinder 25 is provided on the lower fixed platen 21, the weight of the upper movable platen 22 can be reduced.

[0072] When the clamping cylinder 25 is provided on the lower fixed platen 21, the height from the floor to the upper surface of the lower fixed platen 21 is inevitably increased. If the upper surface of the lower fixed platen 21 is elevated above a certain level, the heights of the mold exchange carriage (not shown) and the injection units 10A and 10B must also be increased, which may reduce usability for customers. However, according to this embodiment, the rotary platen 224 and the half nuts 26 are provided on the upper movable platen 22 side, thereby preventing an increase in the height of the upper surface of the lower fixed platen 21. Furthermore, by providing the adjustment mechanism 27 on the lower fixed platen 21 so as to be horizontally parallel to the clamping cylinder 25, the vertical position of the rod 251 can be adjusted without significantly increasing the height of the upper surface of the lower fixed platen 21. This prevents the height from being significantly increased compared to conventional fixed platens, thereby reducing a decrease in usability for customers.

[0073] <Second embodiment> In the first embodiment, it has been described that the first and second flanges 256, 257 are provided on the upper surface of the lower fixed platen 21, and replacement of the seal member of the mold clamping cylinder 25 is achieved by pulling out the rod 251 from above to the extent that the replacement location is exposed. However, the first and second flanges 256, 257 may be provided on the lower surface of the lower fixed platen 21, and replacement of the seal member may be achieved by pulling out the rod 251 from below to the extent that the replacement location is exposed.

[0074] 7 is a schematic front view showing a rotary injection molding machine 1A according to a second embodiment. As shown in FIG. 7, the rotary injection molding machine 1A according to the second embodiment differs from the rotary injection molding machine 1 according to the first embodiment in that the rotary injection molding machine 1A includes a clamping unit 20A having a lower fixed platen 21A instead of the clamping unit 20 having a lower fixed platen 21. The lower fixed platen 21A differs from the lower fixed platen 21 according to the first embodiment in that, instead of the mounting structure 212, an installation structure 212A extending more vertically than the installation structure 212 is provided in the space defined between the lower surface of the lower fixed platen 21A and the floor F on which the clamping unit 20A is installed, and in that first and second flanges 256, 257 are detachably provided on the lower surface rather than the upper surface.

[0075] When replacing the seal member of the piston 253, the first and second flanges 256, 257 are removed from the lower stationary platen 21A, and the rod 251 and the piston 253 of the clamping cylinder 25, which are suspended by a crane, are lowered downward. This requires a work space S below the clamping cylinder 25. Therefore, it is desirable that the installation structure 212A of the lower stationary platen 21A has a length that positions the lower stationary platen 21A at a height that allows the work space S to be defined below it. Specifically, it is essential that the height of the work space S be higher than the sum of the vertical length of the protruding portion of the rod 251 below the piston 253 and the vertical length of the piston 253. The installation structure 212A may be formed to a length that satisfies these conditions. Furthermore, since the piston 253 may also be removed from the rod 251, the height at which the removed piston 253 can be moved laterally and the height of the work space required for this may also be considered.

[0076] In the second embodiment, the work space S is defined below the lower fixed platen 21A, and therefore the height of the upper surface of the lower fixed platen 21A from the floor F is significantly higher than that of the lower fixed platen 21 according to the first embodiment. Therefore, to facilitate operations such as mold replacement, the rotary injection molding machine 1A is provided with a work platform 41 in front of the machine. The work step 42 of the work platform 41 is a long, plate-like member extending in the left-right direction and having a width sufficient for an operator to work, and handrails 44 are provided at both ends in the width direction (front-rear direction) to prevent the operator from falling. Both left and right ends of the work step 42 reach the sides of the injection units 10A and 10B. The injection units 10A and 10B according to the second embodiment have bases that are higher in the vertical direction by the height of the work space S compared to the injection unit 10 according to the first embodiment. Stairs 46 are provided at both left and right ends of the work step 42 to facilitate the operator's ascent and descent of the work step 42.

[0077] In the second embodiment, it is desirable to increase the height of not only the injection unit 10 but also the mold exchange unit such as the mold exchange carriage accordingly.

[0078] The first and second flanges 256, 257 are attached to the underside of the lower fixed platen 21A, and other aspects, such as their structure, their means of connecting with each other, and the methods of attaching and detaching them to the cylinder barrel of the mold clamping cylinder 25, are the same as those in the first embodiment, and therefore will not be described here. However, the first flange 256 is different from the first embodiment in that it closes off the lower side of the powerful mold opening oil chamber 254B.

[0079] A method for replacing a seal member according to the second embodiment will be briefly described. Replacing the seal member 258 of the second flange 257 is the same as in the first embodiment. To replace the seal member of the piston 253, the rod 251 is suspended by a crane (not shown), and the first and second flanges 256 and 257 are removed from the lower fixed platen 21A. The rod 251 is then lowered to expose the piston 253 from the lower fixed platen 21A, and the seal member of the piston 253 is replaced in the work space S. There are three methods for replacing the seal member between the upper part of the clamping cylinder 25 and the rod 251. In the first method, the upper movable platen 22 is first removed by a crane. Then, the seal member insertion flange is removed from the lower fixed platen 21A, and the seal member is replaced. In the second method, a split oil seal is used as the seal member. The seal member insertion flange on the upper part of the clamping cylinder 25 is removed, and the split oil seal is replaced. In the third method, the piston 253 is first removed from the rod 251 below the clamping cylinder 25. Then, using a crane, the rod 251 is pulled upward to above the upper surface of the lower fixed platen 21A, and the seal member is replaced.

[0080] <Third embodiment> FIG. 8 is a schematic front view showing the configuration of a rotary injection molding machine according to a third embodiment. As shown in FIG. 8, the floor F may be dug down only below the mold clamping unit 20A by the amount of work space S to form a lower pit P, thereby defining a space between the lower surface of the lower fixed platen 21A and the bottom surface of the pit P of the mold clamping unit 20A, and the installation structure member 212A may be placed there. This configuration allows replacement of the seal member from below, while optimizing the height from the floor F to the upper surface of the lower fixed platen 21A. This allows the use of an existing mold exchange device such as a mold exchange carriage, and does not require increasing the height of the injection unit 10.

[0081] Although embodiments of the invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the inventions and their equivalents as set forth in the claims. [Explanation of symbols]

[0082] 1. Rotary injection molding machine 10,10A,10B injection device 21 Lower fixed plate (fixed plate) 212 Installation structural members 214 Fixed mold 22 Upper movable plate (movable plate) 222 Movable mold 224 Rotary lathe 24 type opening / closing mechanism 241 Ball screw nut (connecting member) 242 Ball screw (rotating member) 244 Drive source (rotation drive unit) 25 Mold clamping cylinder 251 Rod 254A Mold clamping oil chamber (oil chamber) 256 First flange 257 Second flange 26 Half nut (joint) 27 Adjustment mechanism 28 Stopper device (fall prevention mechanism)

Claims

1. A rotary injection molding machine, A lower fixed platen onto which a fixed mold can be attached; an upper movable platen located above the lower fixed platen, having a rotary platen on its lower surface, and capable of attaching a movable mold via the rotary platen; a mold opening / closing mechanism that opens and closes the fixed mold and the movable mold by raising and lowering the upper movable platen; a clamping cylinder that clamps the fixed mold and the movable mold together by pulling a rod that is provided on the lower fixed platen and functions as a tie bar that guides the upper movable platen in an upward and downward movement; a coupling portion provided on the upper movable platen, which couples the rod to the upper movable platen in order to transmit the clamping force of the clamping cylinder to the movable mold; a mold clamping device having an injection device that injects a molding material into a cavity formed between the fixed mold and the movable mold; A rotary injection molding machine comprising:

2. An installation structure member is provided on the lower surface of the lower fixed platen so as to define a space between the lower fixed platen and the installation surface of the mold clamping device.

2. The rotary injection molding machine according to claim 1.

3. The height from the installation surface of the mold clamping device to the upper surface of the lower fixed platen is 0.9 m or more and 2.0 m or less.

2. The rotary injection molding machine according to claim 1.

4. The mold clamping device is provided with an adjustment mechanism that can adjust the vertical position of the rod and is detachable from the rod.

2. The rotary injection molding machine according to claim 1.

5. The mold opening and closing mechanism includes: a connecting member provided on either the lower fixed platen or the upper movable platen and connected to either the lower fixed platen or the upper movable platen so as not to rotate relative to the either the lower fixed platen or the upper movable platen; a rotating member provided on the other of the lower fixed platen and the upper movable platen and screwed to the connecting member so as to be rotatable relative to the connecting member; a rotation drive unit that rotates the rotating member relative to the connecting member to raise and lower the upper movable platen; 2. The rotary injection molding machine according to claim 1, comprising:

6. The mold clamping device further includes a fall prevention mechanism that prevents the upper movable platen from falling.

2. The rotary injection molding machine according to claim 1.

7. the mold clamping cylinder is located within the lower fixed platen and has an oil chamber for pulling the rod, A flange is provided on the upper surface of the lower fixed platen around the rod, and is detachable from the lower fixed platen to close the oil chamber.

2. The rotary injection molding machine according to claim 1.

8. A method for operating a rotary injection molding machine that performs injection molding using a lower fixed platen to which a fixed mold can be attached, and an upper movable platen that is located above the lower fixed platen and has a rotary platen on its underside, and to which a movable mold can be attached via the rotary platen, comprising: a mold opening / closing mechanism is used to move the upper movable platen closer to the lower fixed platen to close the fixed mold and the movable mold, thereby forming a primary molding cavity; a rod functioning as a tie bar for guiding the upper movable platen in its vertical movement is coupled to the upper movable platen by a coupling portion provided on the upper movable platen; a clamping cylinder provided on the lower fixed platen pulls the rod to clamp the fixed mold and the movable mold together; a first injection device injects a molding material into the primary molding cavity to form a primary molded product; The mold opening and closing mechanism opens the fixed mold and the movable mold, The movable mold is rotated by the rotary platen to move the primary molded product; the mold opening / closing mechanism moves the upper movable platen closer to the lower fixed platen to close the fixed mold and the movable mold, thereby forming a secondary molding cavity adjacent to the primary molded product; The rod is connected to the upper movable platen by the connecting portion, The rod is pulled by the clamping cylinder to clamp the fixed mold and the movable mold together, A second injection device injects molding material into the secondary molding cavity. How a rotary injection molding machine works.

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