Injection unit and injection molding machine

Abstract

To provide an injection device which can shorten a maintenance time.SOLUTION: An injection device (4A) comprises a pair of piston cylinder units (26A, 27A) on both sides of a heating cylinder (14A). The pair of piston cylinder units (26A, 27A) have one end (41A, 42A) respectively that is connected to a mold clamping unit (2), and are telescopically moved, whereby the heating cylinder (14A) is integrally driven in a direction approaching or separating from the mold clamping unit (2). One of the pair of piston cylinder units (26A, 27A) is configured as a piston cylinder unit with stopping means that is provided with stopping means (40A) which prevents telescopic motion.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an injection device and an injection molding machine, and more particularly to an injection device and an injection molding machine that are driven by a pair of piston cylinder units in a direction toward or away from a mold clamping device. [Background technology]

[0002] As described in Patent Document 1, for example, the injection device includes a heating cylinder, a screw inserted in the heating cylinder, and a pair of piston cylinder units arranged on both sides of the heating cylinder. One end of each of the pair of piston cylinder units is connected to a mold clamping device, and the other end is connected to a member of the injection device. When the pair of piston cylinder units are extended or retracted, the injection device approaches or moves away from the mold clamping device. This allows the injection nozzle provided at the tip of the heating cylinder to touch the mold and move away from it. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-255476 A Summary of the Invention [Problem to be solved by the invention]

[0004] When performing maintenance on the injection device, such as replacing the heating cylinder, the screw, or the injection nozzle, it is necessary to disconnect the pair of piston cylinder units from the mold clamping device in advance. The pair of piston cylinder units are disconnected from the mold clamping device, and the injection device is rotated by the rotation device, or the injection device is raised and lowered by the lifting device. Then, maintenance is performed on the injection device. When the maintenance is completed, the injection device is returned to its original position, and the pair of piston cylinder units are reconnected to the mold clamping device. In this way, every time maintenance is performed on the injection device, it is necessary to disconnect the pair of piston cylinder units from the mold clamping device in advance, and reconnect them after the maintenance. This causes a problem that the work time increases.

[0005] The present disclosure provides an injection device and an injection molding machine that can reduce the work time required for maintenance.

[0006] Other objects and novel features will become apparent from the description of this specification and the accompanying drawings. [Means for solving the problem]

[0007] The present disclosure is directed to an injection device that includes a heating cylinder, a screw provided in the heating cylinder, and a pair of piston cylinder units arranged on both sides of the heating cylinder. One end of each of the pair of piston cylinder units is connected to a mold clamping device, and the heating cylinder and the screw are driven integrally in a direction toward or away from the mold clamping device by extending and contracting the units. The present disclosure is directed to one of the pair of piston cylinder units. only is configured as a piston cylinder unit having a stop means provided with a stop means that disables extension and contraction. Effect of the Invention

[0008] According to the present disclosure, when performing maintenance on the injection device, it is no longer necessary to disconnect the piston cylinder unit with stopping means from the mold clamping device, and the work time can be shortened. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a top view showing a twin injection molding machine according to an embodiment of the present invention. [Diagram 2] 1 is a hydraulic circuit diagram showing a movement device according to a first embodiment of the present invention. [Diagram 3] 1 is a hydraulic circuit diagram showing a movement device according to a first embodiment of the present invention. [Figure 4] 1 is a hydraulic circuit diagram showing a movement device according to a first embodiment of the present invention. [Diagram 5] 1 is a hydraulic circuit diagram showing a movement device according to a first embodiment of the present invention. [Figure 6] FIG. 1 is a top view showing a twin injection molding machine according to an embodiment of the present invention. [Figure 7] 1 is a hydraulic circuit diagram showing a movement device according to a first embodiment of the present invention. [Figure 8] FIG. 1 is a top view showing an injection molding machine according to an embodiment of the present invention. [Figure 9] FIG. 1 is a top view showing an injection molding machine according to an embodiment of the present invention. [Figure 10] FIG. 5 is a hydraulic circuit diagram showing a moving device according to a second embodiment of the present invention. [Figure 11] FIG. 11 is a hydraulic circuit diagram showing a moving device according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Specific embodiments will be described in detail below with reference to the drawings. However, the present invention is not limited to the following embodiments. In order to clarify the description, the following description and drawings are appropriately simplified. In each drawing, the same elements are given the same reference numerals, and duplicated descriptions are omitted as necessary. In addition, hatching is omitted in some parts to avoid cluttering the drawings.

[0011] <Twin injection molding machine according to this embodiment> As shown in Fig. 1, the twin injection molding machine 1 according to this embodiment is composed of one mold clamping unit 2 and first and second injection units 4A and 4B. The twin injection molding machine 1 according to this embodiment is a so-called metal injection molding machine that melts and injects metal. However, the present invention can be implemented not only in metal injection molding machines but also in injection molding machines that inject resin.

[0012] <Mold clamping device> The mold clamping device 2 includes a fixed platen 6 fixed to a bed 5, a movable platen 7 slidably provided on the bed 5, and a mold clamping housing 8 slidably provided on the bed 5. The fixed platen 6 and the mold clamping housing 8 are connected by a plurality of tie bars 10, 10, ..., and the movable platen 7 is slidably disposed between the fixed platen 6 and the mold clamping housing 8. A toggle mechanism 12, which is a mold clamping mechanism, is provided between the mold clamping housing 8 and the movable platen 7. When a drive system component (not shown), for example, a mold clamping motor, is driven to bend and extend the toggle mechanism 12, the movable platen 7 slides to open and close the mold. The mold clamping mechanism is not limited to the toggle mechanism 12, and a mold clamping cylinder or the like can be used.

[0013] <Injection device> The first and second injection units 4A and 4B according to this embodiment are disposed symmetrically with respect to the mechanical center line C of the mold clamping unit 2. The components constituting the first and second injection units 4A and 4B are also substantially symmetrical with respect to the mechanical center line C. Therefore, the first injection unit 4A, which is one of the injection units, will be described, and the description of the second injection unit 4B will be omitted unless necessary. Each component of the first injection unit 4A is given a reference number combining a number and the letter "A," and the equivalent components in the second injection unit 4B are given a reference number combining the same number and the letter "B."

[0014] The first injection device 4A includes a heating cylinder 14A, a screw (not shown) that is housed in the heating cylinder 14A, and a screw drive device 15A that drives the screw in the rotational direction and the axial direction. The rear end of the screw is originally connected to the screw drive device 15A and driven by the screw drive device 15A. In this case, the rear end of the screw should be shown in FIG. 1. However, FIG. 1 shows the screw in a state in which it is separated from the screw drive device 15A and completely housed in the heating cylinder 14A. In other words, the heating cylinder 14A and the screw can be removed from the first injection device 4A by a hoist crane for the purpose of maintenance or the like.

[0015] The first injection unit 4A is supported by a support frame 18A. The support frame 18A is provided with first to third plates 20A, 21A, and 22A. The first and second plates 20A and 21A and the second and third plates 21A and 22A are connected by a plurality of rods. The heating cylinder 14A is supported at its center and rear end by the first and second plates 20A and 21A, respectively. The screw drive unit 15A is provided on the third plate 22A.

[0016] <Mobile device> The first injection unit 4A is equipped with a moving unit 25A according to the first embodiment, which moves the heating cylinder 14A, the screw, etc., close to and away from the mold clamping unit 2. The moving unit 25A is equipped with a pair of piston cylinder units 26A, 27A. The pair of piston cylinder units 26A, 27A are arranged on both sides of the heating cylinder 14A, one of which is arranged on the side away from the machine center line C, i.e., on the outside, and the other of which is arranged on the side close to the machine center line C, i.e., on the inside.

[0017] Hereinafter, the pair of piston cylinder units 26A, 27A will be referred to as the outer piston cylinder unit 26A and the inner piston cylinder unit 27A as appropriate. One end 41A, 42A of each of the outer and inner piston cylinder units 26A, 27A is connected to the fixed platen 6, and the other end 43A, 44A is connected to a clevis 29A, 29A provided on the third plate 22A of the support frame 18A.

[0018] The outer and inner piston cylinder units 26A, 27A are extended and retracted by pressure oil supplied by a hydraulic supply mechanism, which will be described next. When extended and retracted, the heating cylinder 14A, the screw, etc. approach the mold clamping unit 2 or move away from the mold clamping unit 2. Incidentally, the inner piston cylinder unit 27A, which is adjacent to the machine center line C, is provided with a stop means, which will be described later, for preventing the supply of pressure oil to its hydraulic circuit to disable extension and retraction. In other words, the inner piston cylinder unit 27A is a piston cylinder unit 27A with a stop means.

[0019] <Hydraulic circuit of the moving device> The moving device 25A is equipped with a hydraulic supply mechanism 30A shown in Fig. 2. The hydraulic supply mechanism 30A is equipped with a hydraulic source 31A, a pressure reducing valve 32A, a directional control valve 34A, and first and second pilot check valves 36A and 37A. The pressure of the pressure oil supplied from the hydraulic source 31A is adjusted by the pressure reducing valve 32A and sent to the directional control valve 34A. The directional control valve 34A has four ports A, B, P, and T, and is switched to three positions by two solenoids a and b, making it a so-called four-port three-position directional control valve. The directional control valve 34A supplies pressure oil to the A port or the B port, or stops the supply.

[0020] The A port of the directional control valve 34A is connected to the first pilot check valve 36A, and the line of pressure oil from the first pilot check valve 36A branches off and is connected to the A ports of the outer and inner piston cylinder units 26A and 27A. On the other hand, the B port of the directional control valve 34A is connected to the second pilot check valve 37A, and the line of pressure oil from the second pilot check valve 37A branches off and is connected to the B ports of the outer and inner piston cylinder units 26A and 27A. However, the line from the second pilot check valve 37A to the B port of the inner piston cylinder unit 27A is provided with a stop means 40A for stopping the supply of pressure oil. The stop means 40A will be described later.

[0021] The first and second pilot check valves 36A and 37A are both valves that prohibit the backflow of pressure oil, but these first and second pilot check valves 36A and 37A are arranged to release the prohibition of backflow of pressure oil from each other. To be more specific, when hydraulic pressure acts on the input side of the first pilot check valve 36A, the second pilot check valve 37A is operated to release the prohibition of backflow of pressure oil in the second pilot check valve 37A. In other words, the backflow of pressure oil is permitted. On the other hand, when hydraulic pressure acts on the input side of the second pilot check valve 37A, the first pilot check valve 36A is operated to release the prohibition of backflow of pressure oil in the first pilot check valve 36A. In other words, the backflow of pressure oil is permitted. The pressure oil that flows back through these first and second pilot check valves 36A and 37A is returned to the oil tank 39A via the directional control valve 34A.

[0022] <Stopping means> The hydraulic pressure supply mechanism 30A is provided with a stop means 40A for stopping the supply of pressure oil on the B port side of the inner piston cylinder unit 27A. In this embodiment, the stop means 40A is composed of a stop valve 45A. The stop valve 45A is switched by a solenoid b to permit or stop the supply of pressure oil. When the supply of pressure oil is stopped by the stop valve 45A, the supply of pressure oil to the B port of the inner piston cylinder unit 27A and the discharge of pressure oil from the B port are both stopped. In other words, the inner piston cylinder unit 27A cannot extend or retract.

[0023] <Action of the twin injection molding machine according to this embodiment> In the twin injection molding machine 1 (see FIG. 1) according to this embodiment, the first and second injection units 4A and 4B are equipped with the moving devices 25A and 25B according to the first embodiment. The first and second injection units 4A and 4B are driven by the moving devices 25A and 25B according to this first embodiment. First, a normal operation method will be described.

[0024] In the first and second injection units 4A and 4B (see FIG. 1), the heating cylinders 14A and 14B and the screw drive units 15A and 15B are brought close to the fixed platen 6 as follows. As shown in FIG. 3, in the hydraulic supply mechanism 30A, the stop valve 45A is kept in the normal state, that is, in the state in which the supply of pressure oil is permitted. Although the hydraulic supply mechanism 30B provided in the moving device 25B of the second injection unit 4B is not shown in the figure, the stop valve 45B is also operated in the same manner in this hydraulic supply mechanism 30B. Hereinafter, the hydraulic supply mechanism 30B (not shown) is assumed to be operated in the same manner as the hydraulic supply mechanism 30A shown in FIG. 3, and a description of the operation of the hydraulic supply mechanism 30B will be omitted.

[0025] The solenoid a is driven in the directional control valve 34A. Then, the pressure oil from the hydraulic source 31A passes through the first pilot check valve 36A and is supplied to the A ports of the outer and inner piston cylinder units 26A and 27A. Since the ends 41A and 42A of the outer and inner piston cylinder units 26A and 27A are fixed to the fixed platen 6 (see FIG. 1), the outer and inner piston cylinder units 26A and 27A are driven in the directions of the arrows 47 and 47 (see FIG. 3). That is, the heating cylinders 14A and 14B approach the fixed platen 6. At this time, the pressure oil is discharged from the B ports of the outer and inner piston cylinder units 26A and 27A. The discharged pressure oil passes through the second pilot check valve 37A and the directional control valve 34A and is returned to the oil tank 39A.

[0026] In the first and second injection units 4A and 4B (see FIG. 1), the heating cylinders 14A and 14B and the screw drive units 15A and 15B, etc. are moved away from the fixed platen 6 as follows. As shown in FIG. 4, in the hydraulic supply mechanism 30A, the stop valve 45A is kept in the normal state, that is, in the state permitting the supply of pressure oil. As described above, the hydraulic supply mechanism 30B provided in the moving device 25B of the second injection unit 4B is not shown in the figure, but is operated in the same manner as the hydraulic supply mechanism 30A.

[0027] The solenoid b is driven in the directional control valve 34A. Pressure oil from the hydraulic source 31A passes through the first pilot check valve 36A and is supplied to the B ports of the outer and inner piston cylinder units 26A and 27A. Since the respective ends 41A and 42A of the outer and inner piston cylinder units 26A and 27A are fixed to the fixed platen 6 (see FIG. 1), the outer and inner piston cylinder units 26A and 27A are driven in the directions of the arrows 48 and 48 (see FIG. 3). In other words, the heating cylinders 14A and 14B, etc. are separated from the fixed platen 6. The pressure oil at the A ports of the outer and inner piston cylinder units 26A and 27A is returned to the oil tank 39A.

[0028] Maintenance of the first and second injection units 4A and 4B (see FIG. 1) is carried out as follows. First, as described above, the moving devices 25A and 25B according to the first embodiment are operated to sufficiently separate the heating cylinders 14A and 14B, the screw driving devices 15A and 15B, etc. from the fixed platen 6. Next, one end portion 41A and 41B of each of the outer piston cylinder units 26A and 26B of the first and second injection units 4A and 4B is detached from the fixed platen 6.

[0029] As shown in FIG. 5, the solenoid b of the stop valve 45A is driven in the hydraulic supply mechanism 30A to stop the supply of pressure oil. The same operation is performed for the hydraulic supply mechanism 30B (not shown). The solenoid a is driven in the directional control valve 34A. Pressure oil from the hydraulic source 31A is supplied to the A port of the outer piston cylinder unit 26A. However, since the flow of pressure oil is prevented by the stop means 40A in the inner piston cylinder unit 27A, pressure oil is not supplied. Since one end 41A of the outer piston cylinder unit 26A is separated from the fixed platen 6 (see FIG. 1), it is driven in the direction of the arrow 50 as shown in FIG. 5. The state in which the outer piston cylinders 26A and 26B of the first and second injection units 4A and 4B are retracted in this manner is shown in FIG. 6.

[0030] At this time, the inner piston cylinder units 27A, 27B are stopped by the stopping means 40A, so the first and second injection units 4A, 4B do not move. The outer piston cylinder units 26A, 26B are retracted, so they do not interfere with the maintenance of the first and second injection units 4A, 4B. The necessary maintenance is carried out.

[0031] In the past, it was necessary to detach one end 42A, 42B of each of the inner piston cylinder units 27A, 27B from the fixed platen 6 during maintenance. However, to do so, an operator had to cross the first and second injection units 4A, 4B as shown by arrows 53, 53 in FIG. 6, which was dangerous. Furthermore, the work to detach them took time. In the twin injection molding machine 1 according to this embodiment including the moving units 25A, 25B according to the first embodiment, it is not necessary to detach the inner piston cylinder units 27A, 27B from the fixed platen 6 during maintenance, which is safe and shortens the work time.

[0032] After the maintenance is completed, as shown in FIG. 7, the hydraulic supply mechanism 30A is operated as follows. Although not shown in the figure, the hydraulic supply mechanism 30B is operated in the same manner. First, the solenoid b in the stop valve 45A is driven to stop the supply of pressure oil to the inner piston cylinder unit 27A. The solenoid b of the directional control valve 34A is driven. Pressure oil from the hydraulic source 31A is supplied only to the B port of the outer piston cylinder unit 26A via the second pilot check valve 37A. One end 41A of the outer piston cylinder unit 26A is driven as shown by the arrow 54. That is, the outer piston cylinder unit 26A extends. Similarly, the outer piston cylinder unit 26B of the second injection device 4B (see FIG. 1) also extends. One end 41A, 41B of each of the outer piston cylinder units 26A, 26B is connected to the fixed platen 6.

[0033] In the above description, the hydraulic supply mechanism 30A shown in Fig. 2 and the hydraulic supply mechanism 30B not shown perform the same operation at the same time. That is, the first and second injection units 4A and 4B perform the same operation. However, since the hydraulic supply mechanisms 30A and 30B are provided independently and separately for the first and second injection units 4A and 4B, it is also possible to operate only one of them. That is, when performing maintenance on only the first injection unit 4A, it is sufficient to operate only the hydraulic supply mechanism 30A.

[0034] <Injection molding machine with one injection unit> The moving device 25A according to the first embodiment shown in FIG. 2 can also be adopted in an injection molding machine having one injection device. FIG. 8 shows an injection molding machine 1' equipped with one injection device 4. In this injection molding machine 1', the devices and members that perform the same functions as those provided in the twin injection device 1 (see FIG. 1) according to this embodiment are given the same reference numerals and their explanations are omitted. The twin injection device 1 is provided with two injection devices 4A and 4B, and the members provided therein are described by using reference numerals combining numbers and the letters "A" and "B." However, in the injection molding machine 1', the members that perform the same functions are given reference numerals consisting of the same numbers and their explanations are omitted.

[0035] The injection molding machine 1' is provided with first and second piston cylinder units 26, 27. These first and second piston cylinder units 26, 27 are also provided with a hydraulic supply mechanism 30A as shown in Fig. 2. In other words, of these first and second piston cylinder units 26, 27, the second piston cylinder unit 27 is provided with a stop means for preventing the supply of pressure oil in the hydraulic circuit to disable extension and contraction, making it a piston cylinder unit 27 with a stop means.

[0036] One ends 41, 42 of the first and second piston cylinder units 26, 27 are both connected to the fixed platen 6. However, in this embodiment, the other ends 43, 44 are connected to clevises 29', 29' of the second plate 21 of the support frame 18. In other words, the first and second piston cylinder units 26, 27 are shorter than the pair of piston cylinder units 26A, 27A of the twin injection molding machine 1 according to this embodiment shown in Figure 1. Therefore, in the injection molding machine 1' shown in Figure 8, the distance that separates the injection unit 4 from the fixed platen 6 is slightly shorter, and the injection unit 4 needs to be rotated during maintenance.

[0037] Maintenance of the injection unit 4 in the injection molding machine 1' is performed as follows. First, the pair of piston cylinder units 26, 27 of the moving device 25 are driven to move the injection unit 4 away from the fixed platen 6. Next, one end 41 of the first piston cylinder unit 26 is separated from the fixed platen 6. Next, a hydraulic supply mechanism (not shown) is driven to retract the first piston cylinder unit 26. At this time, the second piston cylinder unit 27 is stopped by a stopping means. The injection unit 4 is rotated as shown in FIG. 9. At this time, the second piston cylinder unit 27 rotates slightly with the rotation of the injection unit 4 because one end 42 of the second piston cylinder unit 27 is connected to the fixed platen 6, but this does not hinder maintenance.

[0038] Once the maintenance is completed, the procedure is reversed; that is, the injection unit 4 is rotated back to its original state. Next, the first piston-cylinder unit 26 is extended and the end portion 41 is connected to the fixed platen 6. In the injection molding machine 1' according to this embodiment, too, only one piston-cylinder unit 27 needs to be disconnected from the fixed platen 6 during maintenance and then reconnected, thereby shortening the work time.

[0039] <Movement device according to the second embodiment> The first and second injection units 4A and 4B of the twin injection molding machine 1 (see FIG. 1) according to this embodiment have been described as being provided with different moving units 25A and 25B, respectively. That is, the hydraulic supply mechanism 30A (see FIG. 2) of the moving unit 25A that moves the first injection unit 4A and the hydraulic supply mechanism 30B (not shown) of the moving unit 25B that moves the second injection unit 4B are provided separately. In contrast, a single common moving unit 25', that is, a moving unit 25' according to the second embodiment, as shown in FIG. 10, may be provided for the first and second injection units 4A and 4B.

[0040] The moving device 25' according to the second embodiment includes one hydraulic supply mechanism 30'. The hydraulic supply mechanism 30' includes a hydraulic source 31, a pressure reducing valve 32, a directional control valve 34, first and second pilot check valves 36, 37, and a stop valve 45, similar to the hydraulic supply mechanism 30A shown in FIG. 2. In this embodiment, the first pilot check valve 36 supplies pressure oil to the A ports of the two outer piston cylinder units 26A, 26B and the A ports of the two inner piston cylinder units 27A, 27B. The second pilot check valve 37 supplies pressure oil directly to the B ports of the two outer piston cylinder units 26A, 26B, and supplies pressure oil via the stop valve 45 to the B ports of the two inner piston cylinder units 27A, 27B.

[0041] In the moving device 25' according to this embodiment, the two inner piston cylinder units 27A, 27B are piston cylinders with a stop means in which the supply of pressure oil is permitted or stopped by the stop valve 45, which is the stopping means 40. Therefore, the same effect as that of the twin injection molding machine 1 according to this embodiment (see FIG. 1) in which different moving devices 25A, 25B are provided for the first and second injection units 4A, 4B, respectively, is achieved, and maintenance can be easily performed.

[0042] <Movement device according to the third embodiment> The hydraulic pressure supply mechanism 30A according to the first embodiment shown in Fig. 2 can be modified as shown in Fig. 11. In a hydraulic pressure supply mechanism 30A' according to a third embodiment shown in Fig. 11, a stop means 40A' is provided on the A port side of the inner piston cylinder unit 27A and is composed of an electromagnetic on-off valve 57A. This embodiment also exerts the same effect as the hydraulic pressure supply mechanism 30A according to the first embodiment.

[0043] Although the invention made by the present inventor has been specifically described above based on the embodiment, it goes without saying that the present invention is not limited to the embodiment already described, and various modifications are possible without departing from the gist of the invention. The above-described examples may be implemented in appropriate combination. [Explanation of symbols]

[0044] 1 Twin injection molding machine 2 Clamping unit 4A First injection unit 4B Second injection unit C Machine centerline 5 Bed 6 Fixed plate 7 Movable plate 8 Clamping housing 10 Tie bar 12 Toggle mechanism 14A Heating cylinder 15A Screw drive unit 18A Support frame 20A First Plate 21A Second Plate 22A Third plate 25A Moving device 26A Outer piston cylinder unit 27A Inner piston cylinder unit 29A Clevis 30A Hydraulic supply mechanism 31A Hydraulic source 32A Pressure reducing valve 34A Directional valve 36A First pilot check valve 37A Second pilot check valve 39A Oil tank 40A Stopping means 41A One end 42A One end 43A The other end 44A Other end 45A Stop valve 47A Solenoid valve

Claims

1. A heating cylinder; A screw provided in the heating cylinder; A pair of piston cylinder units arranged on both sides of the heating cylinder, the pair of piston cylinder units are each connected at one end to a mold clamping device, and are installed so that, by extending and contracting, the heating cylinder and the screw are integrally driven in a direction approaching or moving away from the mold clamping device, The injection device, wherein only one of the pair of piston cylinder units is a piston cylinder unit with stopping means provided with stopping means that disables extension and contraction.

2. 2. The injection apparatus according to claim 1, wherein said stopping means comprises a valve provided in a hydraulic circuit of said piston-cylinder unit having said stopping means.

3. 3. The injection apparatus of claim 2, wherein the valve comprises a stop valve.

4. The pair of piston cylinder units include The other end of each of the screws is connected to a member of a screw drive device that drives the screw, The injection device according to any one of claims 1 to 3, wherein the screw drive device is installed so as to be driven integrally with the heating cylinder and the screw in a direction approaching or moving away from the mold clamping device by extending and contracting.

5. a mold clamping device that clamps the mold; an injection device that injects an injection material into the mold, The injection device includes a heating cylinder and A screw provided in the heating cylinder; A pair of piston cylinder units arranged on both sides of the heating cylinder, the pair of piston cylinder units are each installed such that one end is connected to the mold clamping device, and the heating cylinder and the screw are integrally driven toward or away from the mold clamping device by extending and contracting the piston cylinder units; An injection molding machine, wherein only one of the pair of piston cylinder units is a piston cylinder unit with a stop means provided with a stop means that disables extension and contraction.

6. An injection molding machine including the mold clamping device and two of the injection devices, the two injection units are disposed symmetrically with respect to a mechanical center line of the mold clamping unit, 6. The injection molding machine according to claim 5, wherein the piston-cylinder unit having the stopping means of each of the two injection devices is a piston-cylinder unit closer to the center line of the machine.

7. 7. The injection molding machine according to claim 5, wherein the stopping means comprises a valve provided in a hydraulic circuit of the piston-cylinder unit having the stopping means.

8. 8. The injection molding machine of claim 7, wherein the valve comprises a stop valve.

9. The pair of piston cylinder units include The other end of each of the screws is connected to a member of a screw drive device that drives the screw, The injection molding machine according to any one of claims 5 to 8, wherein the screw drive device is installed so as to be driven integrally with the heating cylinder and the screw in a direction approaching or moving away from the mold clamping device by extending and contracting.

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