JPH05192971A - Injection molding machine - Google Patents

Abstract

PURPOSE:To remarkably reduce the cost, make a machine compact and improve general utility by utilizing directly an existing injection molding machine provided with a single hydraulic cylinder. CONSTITUTION:At least one booster cylinder 3 provided with a built-in booster ram 4, the pressure receiving area of which is different in an oil chamber Ca on one side and another oil chamber Cc on the other side, is connected between an after-oil chamber Cb of a hydraulic cylinder 2 for driving a screw forward and backward and a hydraulic pump 5 for the purpose of increasing (decreasing in quantity) or decreasing (increasing in quantity) the pressure oil discharged out of the hydraulic pump 5 and feed the pressure oil to the after-oil chamber Cb.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding machine having a hydraulic cylinder for driving a screw forward and backward.

[0002]

2. Description of the Related Art A hydraulic injection molding machine having a hydraulic cylinder for driving a screw forward and backward is known. By the way, in this type of injection molding machine, when setting the molding conditions such as the injection speed and the injection pressure, the optimum value is set according to the size and shape of the molded product. Since it depends on the capacity, the setting range is limited in the case of a single hydraulic cylinder.

For this reason, in the past, there has been a conventional method, 2-146017.
As disclosed in Japanese Patent Publication No. 59-15295 and Japanese Patent Publication No. 59-15295, a multi-stage hydraulic cylinder capable of taking out a plurality of outputs of different sizes is used, thereby expanding the setting range when setting molding conditions. I was trying. The former injection molding machine is one in which a plurality of pairs of single hydraulic cylinders arranged in parallel at positions symmetrical to the screw shaft center are connected to the screw, and the latter injection molding machine. Is made up of several rams with different diameters that are connected step by step in order of increasing diameter, and a working chamber composed of this ram and cylinder is formed into a cylindrical shape, and an oil inflow pipe is connected to each working chamber. Then, the hydraulic cylinders are guided to the directional control valve, and oil is press-fitted into the respective working chambers at the same time or with a time difference between the respective working chambers to operate the hydraulic cylinders.

[0004]

However, the above-mentioned conventional multistage injection molding machines have the following problems to be solved.

First, since the structure of the entire injection device including the hydraulic cylinder is significantly different from that of the single hydraulic cylinder, the existing injection molding machine equipped with the single hydraulic cylinder cannot be used as it is, resulting in a significant cost increase. Invite.

Secondly, since the hydraulic cylinder itself which directly drives the screw is increased in size or quantity, the size of the entire injection apparatus is increased.

The present invention has solved the problems existing in such conventional techniques. By directly utilizing the existing injection molding machine equipped with a single hydraulic cylinder, it is possible to greatly reduce the cost and reduce the size and size. It is an object of the present invention to provide an injection molding machine that is both versatile and versatile.

[0008]

SUMMARY OF THE INVENTION In the present invention, in constructing an injection molding machine 1 including a hydraulic cylinder (hereinafter referred to as a main cylinder) 2 for driving a screw forward and backward, particularly, one side oil partitioned by a booster ram 4. The pressure receiving areas of the chamber Ca and the other side oil chamber Cc are different, and the pressure oil discharged from the hydraulic pump 5 is increased (reduced) or reduced in pressure by connecting between the rear oil chamber Cb of the main cylinder 2 and the hydraulic pump 5. It is characterized by comprising at least one booster cylinder 3 that can be (increased) and supplied to the rear oil chamber Cb.

In this case, the main cylinder 2 or the booster cylinder 3 is provided with switching valves V1 and V2 capable of selectively connecting the hydraulic pump 5, and one side oil chamber Ca or the other side oil chamber of the booster cylinder 3 is provided. A switching valve V3 capable of selectively connecting the hydraulic pump 5 or the main cylinder 2 to Cc can be provided.

[0010]

In the injection molding machine 1 according to the present invention, for example, the pressure receiving area Sa [cm ² ] of the one side oil chamber Ca, the pressure receiving area Sb [cm ² ] of the rear oil chamber Cb and the pressure receiving area of the other side oil chamber Cc are used. Sc [c
m ² ], Sa: Sb: Sc = 1: 2: 2, and the output of the main cylinder 2 when the pressure oil is supplied to the rear oil chamber Cb, that is, the output to the screw is F
If o [kg], then the output to the screw is F
It is possible to select three sizes of a = Fo / 2, Fb = Fo, Fc = 2Fo, in other words, three different injection pressures.

That is, when the hydraulic pump 5 is directly connected to the main cylinder 2 by switching the switching valves V1 and V2, the pressure oil discharged from the hydraulic pump 5 is directly supplied to the rear oil chamber Cb and the output Fb to the screw is output. Is Fb = Sb ×
Po = Fo. However, Po [kg / cm ² ] is the discharge pressure of the hydraulic pump 5.

On the other hand, by switching the switching valves V1 and V2, the hydraulic pump 5 is connected to the booster cylinder 3, and by switching the switching valve V3, the pressure oil discharged from the hydraulic pump 5 is supplied to one side of the booster cylinder 3. If the pressure oil discharged from the other side oil chamber Cc is supplied to the rear oil chamber Cb while being supplied to the oil chamber Ca, the pressure oil discharged from the hydraulic pump 5 is depressurized (increased) by the booster cylinder 3 and then It is supplied to the oil chamber Cb. As a result, the output F to the screw
a is Fa = Sb × (Sa / Sc) × Po = 1 / 2Fo
Becomes

On the other hand, the hydraulic pump 5 is connected to the booster cylinder 3
In this state, the switching valve V3 is switched to supply the pressure oil discharged from the hydraulic pump 5 to the other side oil chamber Cc of the booster cylinder 3 and also to the one side oil chamber Ca.
By supplying the pressure oil discharged from the rear oil chamber Cb to the rear oil chamber Cb, the pressure oil discharged from the hydraulic pump 5 is pressurized (reduced) by the booster cylinder 3 and then supplied to the rear oil chamber Cb. As a result, the output Fc for the screw is Fc = Sb × (Sc
/ Sa) × Po = 2Fo.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, preferred embodiments according to the present invention will be described in detail with reference to the drawings.

First, the structure of the injection molding machine according to the present invention will be described with reference to FIG.

In the figure, reference numeral 1 is an injection molding machine, and in particular,
2 shows an injection device. Reference numeral 11 denotes a screw, the front end side of which is inserted into the heating cylinder 10 and the rear end of the screw 11 is connected to the screw drive mechanism E side. The screw drive mechanism E includes a main cylinder (hydraulic cylinder for driving the screw forward and backward) 2 and an oil motor 1 for driving the screw rotation.
It consists of two. Further, 13 is a material supply port, and 14 is an injection nozzle.

The main cylinder 2 has a cylinder portion 15, and the cylinder portion 15 has a single rod type piston portion 1.
Built-in 6. Piston rod 16b of piston part 16
Projects forward from the front end of the cylinder portion 15 and connects the rear end of the screw 11 to the front end of the piston rod 16b. The inside of the cylinder portion 15 is partitioned by the piston body 16u, and the front of the piston body 16u is the front oil chamber Co and the rear is the rear oil chamber Cb. The pressure receiving area of the piston portion 16 in the rear oil chamber Cb is Sb [cm ² ]. Also,
An output shaft of the oil motor 12 is connected to the rear end of the piston portion 16 via a spline mechanism 17.

On the other hand, the booster cylinder 3 is provided separately from the main cylinder 2. This booster cylinder 3 has a booster ram 4 built-in, and inside the booster cylinder 3 is a one-side oil chamber Ca partitioned by the booster ram 4.
And the other side oil chamber Cc is provided. In this case, the booster ram 4 is constituted by a single rod type, the pressure receiving area of the one side oil chamber Ca is Sa [cm ² ] and the pressure receiving area of the other side oil chamber Cc is Sc.
[Cm ² ]. The booster cylinder 3 is a screw 11
Is not directly driven, and the tip of the booster ram 4 is free, so the installation location is arbitrary. It is desirable to select the pressure receiving area Sa: the pressure receiving area Sb: the pressure receiving area Sc = 1: 2: 2.

On the other hand, the front oil chamber Co, the rear oil chamber Cb, the one side oil chamber Ca and the other side oil chamber Cc are connected to the hydraulic circuit 20. The hydraulic circuit 20 includes a hydraulic pump 5, an oil tank 22, four port switching valves V1 and V3, three port switching valves V2 and 23, and a relief valve 24, which are connected as shown in FIG.

Next, the overall operation of the injection molding machine 1 according to the present invention will be described with reference to FIGS. 1 and 2.

In the injection molding machine 1, if the operation of the main cylinder 2 is controlled, the screw 11 can be moved forward and backward, and if the operation of the oil motor 12 is controlled, the rotation of the screw 11 can be controlled.

On the other hand, in the operation control of the main cylinder 2, the screw 1 when pressure oil is supplied to the rear oil chamber Cb
If the output for 1 is Fo [kg], the screw 11
As outputs for, Fa = Fo / 2, Fb = Fo, F
Three sizes of c = 2Fo, that is, three different injection pressures can be selected. FIG. 2 shows switching valves V1, V2, V for switching control when selecting the outputs Fa, Fb, Fc.
3 is a control matrix, and the mark ◯ means switching to the corresponding symbol a side or the symbol b side in FIG. 1, and both unmarked means switching to the neutral position.

First, the switching valve V1 is set to the neutral position, and the switching valve V2 is set.
Is switched to the symbol a side and the switching valve V3 is switched to the symbol b side to supply the pressure oil discharged from the hydraulic pump 5 to the one side oil chamber Ca of the booster cylinder 3 and the pressure oil discharged from the other side oil chamber Cc. If it is supplied to the rear oil chamber Cb, the hydraulic pump 5
The pressure oil discharged from is reduced in pressure by the booster cylinder 3 and then supplied to the rear oil chamber Cb. As a result, the output for the screw is Fa = Sb × (Sa / Sc) × Po = 1 /
It will be 2 Fo.

On the other hand, the switching valve V1 is switched to the symbol a side, the switching valve V2 is switched to the symbol b side, and the switching valve V3 is switched to the neutral position, and the pressure oil discharged from the hydraulic pump 5 is directly transferred to the rear oil chamber C.
If it is supplied to b, the output to the screw is Fb = Sb ×
Po = Fo.

On the other hand, the switching valve V1 is at the neutral position, and the switching valve V2 is
Is switched to the symbol a side and the switching valve V3 is switched to the symbol a side to supply the pressure oil discharged from the hydraulic pump 5 to the other side oil chamber Cc of the booster cylinder 3 and to discharge the pressure oil discharged from the one side oil chamber Ca. If it is supplied to the rear oil chamber Cb, the hydraulic pump 5
The pressure oil discharged from is boosted by the booster cylinder 3 and then supplied to the rear oil chamber Cb. As a result, the output to the screw is Fc = Sb × (Sc / Sa) × Po = 2F
It becomes o.

In the embodiment, the case where the pressure oil discharged from the hydraulic pump 5 is increased or reduced has been described, but the pressure oil can be similarly decreased or increased, and in this case, the speed control of the screw is performed. Available.

The embodiment has been described in detail above.
The present invention is not limited to such an embodiment.
For example, the screw in the present invention is a concept including various injection members such as a plunger capable of injecting resin. Also,
Although the embodiment exemplifies one booster cylinder, a combination of two or more booster cylinders may be used, and in this case, the number of variable output stages can be increased. Other,
The detailed configuration, shape, and the like can be arbitrarily changed without departing from the scope of the present invention.

[0028]

As described above, in the injection molding machine according to the present invention, the pressure receiving areas of the one-side oil chamber and the other-side oil chamber that are partitioned by the booster ram are different, and the connection between the rear oil chamber of the main cylinder and the hydraulic pump is made. By providing at least one booster cylinder capable of increasing (decreasing) or reducing (increasing) the pressure oil discharged from the hydraulic pump to the rear oil chamber, in particular, the existing single hydraulic cylinder is provided. By directly using the injection molding machine, a multi-stage injection molding machine can be configured, and it is possible to significantly reduce the cost and reduce the size and size of the machine, and to achieve a remarkable effect of increasing versatility.

[Brief description of drawings]

FIG. 1 is a configuration diagram including a partial cross section of an injection molding machine according to the present invention,

FIG. 2 is a control matrix diagram of each switching valve with respect to output,

[Explanation of symbols]

1 injection molding machine 2 screw forward / backward drive hydraulic cylinder (main cylinder) 3 booster cylinder 4 booster ram 5 hydraulic pump Ca one side oil chamber Cb rear oil chamber Cc other side oil chamber V1 switching valve V2 switching valve V3 switching valve

Claims (3)

[Claims] 1. An injection molding machine comprising a hydraulic cylinder for advancing / retreating a screw, wherein the pressure receiving areas of one side oil chamber and the other side oil chamber, which are partitioned by a booster ram, are different, and the rear oil chamber of said hydraulic cylinder and a hydraulic pump. An injection characterized by comprising at least one booster cylinder capable of increasing (decreasing) or decompressing (increasing) the pressure oil discharged from the hydraulic pump by connecting the booster cylinder to the rear oil chamber. Molding machine. 2. The injection molding machine according to claim 1, further comprising a switching valve capable of selectively connecting a hydraulic pump to the hydraulic cylinder or the booster cylinder for advancing and retracting the screw. 3. A switching valve capable of selectively connecting a hydraulic pump or a screw advancing / retreating hydraulic cylinder to one side oil chamber or the other side oil chamber of the booster cylinder. Injection molding machine.