JP3500284B2 - Injection equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection device used in an injection molding machine. More specifically, the present invention relates to an injection device capable of detecting the resin pressure applied to a nozzle and being measured without contacting the resin.

[0002]

2. Description of the Related Art In injection molding, it is preferable that the resin pressure is uniform from the beginning to the end in one injection step (one shot), because the density of the injection-molded product obtained will be constant. A structure for detecting and controlling the resin pressure in the process and the measuring process is required.

Conventionally, in an electric injection molding machine, a load cell is provided at the rear end of a screw, the reaction force of resin pressure applied to the screw is detected by this load cell, and the speed of the servomotor or the speed of the servomotor is adjusted based on the detected load cell. A control mechanism for feedback control of torque was adopted. On the other hand, in the case of a hydraulic injection molding machine, a pressure sensor is provided in the hydraulic cylinder, the reaction force of the resin pressure applied to the screw is detected by this pressure sensor, and based on this, the hydraulic cylinder is feedback-controlled so as to reach the command pressure. It adopted a control mechanism that

However, in any of the above control mechanisms, the resin pressure reaction force acting on the screw is detected, and a force in the backward direction is generated by the screw action of the screw itself at the time of measurement, which causes an error. Moreover, the difference is not constant, but varies due to various factors, so that there is a problem that the resin pressure cannot be controlled to be constant.

Further, there is a method of directly detecting the resin pressure at the tip of the screw with a pressure sensor without detecting the reaction force as described above, but it is expensive because a small sensor such as temperature drift needs to be used. Moreover, since the sensor itself is in direct contact with the resin, the resin easily stays in this portion, and there is a problem in changing the resin.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide an injection device for measuring the resin pressure at the nozzle portion without contacting the resin.

[0007]

Thus, according to the invention of "Claim 1" of the present application, the heating which has the "heater (h2) and which can knead, melt and inject the resin in cooperation with the screw (2)" A tube (1) and a nozzle (N provided at the tip of the heating tube (1)
1), the load cell (L1) is provided outside the nozzle (N1) and between the nozzle (N1) and the heating cylinder (1), and the load cell (L1) is connected to the heating cylinder (1). ), And fix the above nozzle (N1)
By fixing the load cell to the load cell (L1) above.
The resin pressure in the heating cylinder (1) that affects (1) is applied to the load cell (L1)
An injection device (A1) 'is provided which is configured to detect based on the strain generated in the.

Further, according to the invention of "Claim 2", the heating cylinder (1) having the "heater (h2) and capable of kneading / melting / injecting the resin in cooperation with the screw (2)" A nozzle (N2) housed in the tip of the heating cylinder (1), and a heating cylinder (1)
The heating cylinder (1) is provided with a load cell (L2) interposed between the tip of the heating cylinder (1) and the nozzle (N2) and held in the heating cylinder (1), and the heating applied to the nozzle (N2). There is provided an injection device (A2) 'configured to detect the resin pressure in the cylinder (1) based on the strain generated in the load cell (L2).

In the injection apparatus according to the "claim 1" of the present application (hereinafter referred to as the injection apparatus of the first invention of the present application) (A1), the heating cylinder (1) has a tip portion of a load cell (L1) and a nozzle (N1). It has a configuration similar to that known in the art, except that it is slightly modified for mounting. The heating cylinder (1) is
The tip of the heating cylinder to which the load cell (L1) and the nozzle (N1) are attached may be separated so as to be connectable to the other heating cylinder main body.

In the injection device (A1) of the first invention of the present application, the load cell (L1) is used so as to detect strain. At this time, it is preferable to detect shear strain, but the invention is not particularly limited to this. Further, in order to dispose the nozzle (N1) outside, a donut shape having a central hole through which the nozzle (N1) is inserted is preferable, but the present invention is not limited to this.

In the injection device (A1) of the first invention of the present application, the nozzle (N1) has a shape such that the main body can be inserted into the tip of the heating cylinder (1), and the load cell (L1) is held on the outer periphery of the main body and attached thereto. It is preferable that the flange portion (L1a) is provided so as to be formed.

In the injection device according to claim 2 of the present application (hereinafter referred to as the injection device of the second invention of the present application) (A2), the heating cylinder (1) has a nozzle (N2) and a load cell (L2) at its tip. It has the same structure as that known in the art, except that it is housed and slightly changed so as not to fall off. In addition,
The heating cylinder (1) may be separably connectable to the tip member (111) of the heating cylinder (1) to which the load cell (L2) and the nozzle (N2) are attached and the other heating cylinder body member.

In the injection device (A2) of the second invention of the present application, the load cell (L2) used is configured to detect strain. In this case, it is preferable to detect the compression distortion, but the invention is not limited to this. Further, a central hole for inserting a nozzle (N2) described later is provided, and the heating cylinder
A donut shape having an outer periphery that can be stored in (1) or the tip member (112) is preferable, but not limited to this.

In the injection device (A2) of the second invention of the present application, the nozzle (N2) has a shape such that the main body can be inserted into the tip of the heating cylinder (1) and the flange portion (N) for pressing the load cell (L2) around the main body.
Those provided with 2a) are preferred.

[0015]

According to the invention of "Claim 1" of the present application, the load cell (L1) is fixed to the heating cylinder tip (11) and the nozzle (N1) is fixed to the load cell (L1). ,
In the injection process, the resin pressure applied to the nozzle (N1) is a force in the injection direction acting on the part of the load cell (L1) where the nozzle (N1) is fixed, but the load cell (L1) itself is the tip of the heating cylinder.
Since it is fixed to (11), the load based on this causes distortion in the load cell (L1). Therefore, if the strain is controlled to a desired value, the resin pressure in the injection process will be controlled.

According to the invention of "Claim 2" of the present application,
The load cell (L2) is sandwiched between the heating cylinder front end edge portion (112a) and the nozzle (N2) in the heating cylinder front end portion (112), so that the load cell (L2) is generated by the resin pressure applied to the nozzle (N2) in the injection process. Distortion occurs in L2). Therefore, if the strain is controlled to a desired value, the resin pressure in the injection process will be controlled.

[0017]

The present invention will be described in detail below with reference to the illustrated embodiments, but the present invention is not limited to these. Example 1 FIG. 1 is a schematic cross-sectional view of a main part of an electric injection molding machine having an example of an injection device according to the "claim 1" of the present application. In the figure, the electric injection molding machine (M) is a raw material supply hopper.
(h1), an injection cylinder (A1) comprising a heating cylinder (1) provided with a heater (h2), and a heating cylinder housed in the injection cylinder (A1)
Screw (2) that rotates and moves forward / backward in (1), screw rotation servomotor (3a1) and injection servomotor (3b1)
It is mainly composed of a drive transmission unit (3) having

The injection cylinder (A1) is inserted and fixed to a front fixing plate (30) of a drive transmission portion (3) described later. The raw material supply hopper (h1) is attached to the front fixing plate (30) so as to communicate with the inside of the injection cylinder (A1).

The tip of the injection cylinder (A1) is shown in FIG.
Nozzle (N1) through load cell (L1) as shown in
Is provided. That is, the tip block portion (11) of the heating cylinder (1) is connected to the nozzle from the heating cylinder (1) as shown in FIG.
A throttle channel (12) communicating with (N1) is formed inside, and a recess (11a) into which the rear end of the nozzle (N1) is inserted is formed at its tip. The tip block portion (11) is integral with the heating cylinder in this example, but may be configured as a detachable separate body.

The load cell (L1) is of a donut shape having an insertion hole (L1a) for inserting the body of the nozzle (N1), and is provided on the end surface of the tip block (11) of the heating cylinder (1). It is fixed by screws (13).

Further, the nozzle (N1) is, as shown in FIG.
A flange (N1a) is formed on the body, and this nozzle
(N1) is a recess (11) on the end surface of the tip block (11) of the heating cylinder (1).
The flange (N1a) is fixed to the load cell (L1) with a screw (14).

The load cell (L1) is constructed so as to be able to detect shear strain in the thickness direction (the arrow in the figure), and its detection signal is outputted to the control unit (4) described later. .

The drive transmission part (3) has a frame composed of a front fixing plate (30), a rear fixing plate (31) and a tie bar (32) for fixing them at a predetermined interval. Further, the rotation drive transmission unit (3a) and the injection drive transmission unit (3b) are integrally formed.

The rotary drive transmission part (3a) includes a large rotation gear (3a2) in which the rear end of the screw (2) is embedded and fixed, a screw rotation servomotor (3a1), and the servomotor (3a1). The small gear (3a3) fixed to the rotating shaft and the large gear for rotation
(3a2) and the small gear (3a3) tension belt (3a3)
a4) and an encoder (3a5) attached to the rotation servomotor (3a1).

The injection drive transmission part (3b) is a large gear for rotation.
(3a2) via a bearing group (3b21) rotatably supports a rotation support member (3b2), a bearing nut (3b4) connected to the rear end of this rotation support member (3b2), and the front half An injection drive shaft (3b5) in which a screw part to be screwed into the bearing nut (3b4) is formed and a spline shaft part is formed in the latter half part, and is fixed to the rear end of the spline shaft part of the injection drive shaft (3b5). Large gear (3b6), injection servo motor (3b1), and small gear (3b8) fixed to the rotation axis of the injection servo motor (3b1).
And a timing belt (3b9) stretched over the large gear (3b6) and the small gear (3b8), and a position detection device (3b10) attached to the injection servomotor (3b1). ing.

The rotary drive transmission portion (3a), the rotary support member
(3b2) and bearing nut (3b4) are integrated into the tie bar
It is reciprocally supported along (32).

(4) is a control unit for controlling the drive of the entire injection molding machine, and one function thereof is to preset the signal detected by the load cell (L1) in this control unit. It is configured to instruct the servomotor for injection (3b1) to operate based on this difference compared with the set value.

Next, operations of the electric injection molding machine (M) mainly relating to resin metering / injection / resin pressure control will be described. First, with reference to FIG. 1, an outline will be given of measurement of resin in injection molding. That is, the timing belt (3a4) is activated by the operation of the screw rotation servomotor (3a1).
The large rotation gear (3a2) rotates via the screw, and the screw (2) integrally connected to the large rotation gear (3a2) rotates. At this time, the rotation supporting member (3b2) and the bearing nut (3b4) connected to the rotation supporting member (3b2) do not rotate because they are interposed by the bearing group (3b21).

On the other hand, the raw material resin taken into the heating cylinder (1) of the injection cylinder (A1) from the raw material supply hopper (h1) with the rotation of the screw (2) is sent out to the tip side thereof. It is heated to melt and kneaded.

The raw material resin thus melted is stored in the tip of the heating cylinder (1) of the injection cylinder (A1), but the screw (2) begins to retract as the storage amount increases. At this time, the rotation drive transmission part (3a), the rotation support member
(3b2) and bearing nut (3b4) are integrated into the tie bar
The bearing nut (3b4) will retreat along (32).
Injection drive shaft (3b5) screwed into it by retreating
Will rotate following, and injection servo motor (3b1)
Rotates passively to allow the above rotation. When the resin has been measured to a predetermined amount as described above, the screw rotation servomotor (3a1) is stopped and the mode is switched to the injection mode.

Next, in the injection mode, when the injection servomotor (3b1) rotates, the large gear (3b6) rotates via the timing belt (3b9) and the injection drive shaft (3b5) rotates. As a result, the bearing nut (3b4) screwed into the threaded portion of the injection drive shaft (3b5) advances. In this way, injection driving is performed.

By the way, in this injection step, the resin melted and kneaded in the heating cylinder (1) is injected through the nozzle (N1). At this time, the resin pressure applied to the nozzle (N1) is Since a force in the injection direction acts on the part where the screw (14) of the load cell (L1) is embedded and its vicinity,
Shear force will be generated between the screw (13) fixing part and its vicinity fixing the load cell (L1) to the heating cylinder (1) and the screw (14) embedding part and its vicinity. . A signal corresponding to the strain (load) of the load cell (L1) due to this shearing force is output to the control unit (4) and compared there with a set value.

At this time, if the signal value is smaller than the set value, the control unit (4) outputs it to the injection servomotor (3b1) and raises its rotational speed until it becomes equal to the set value, whereby the nozzle (N1). Command to increase the resin pressure applied to. If the signal value is larger than the set value, the control unit (4)
Outputs to the injection servomotor (3b1) to decrease its rotation speed so that it becomes equal to the set value, thereby instructing the operation to decrease the resin pressure applied to the nozzle (N1). As described above, the resin pressure in the injection step is controlled to be substantially constant, and an injection-molded product having a substantially uniform density can be obtained.

Further, if the relationship between the load cell (L1) and the control unit is set as follows, the touch pressure at the time of touching the nozzle can be determined and controlled. That is, the nozzle
When the tip of (N1) abuts and presses against the mold sprue, the load cell (L1) is sandwiched between the sprue and the tip block (12) and pressed, but at this time, the load cell (L1) To detect the compressive strain that occurs at the same time, and output the compressive strain signal of the load cell (L1) according to this pressing force to the control unit, and set an appropriate pressing value (which may be in an appropriate range) preset there. If the driving servomotor can be controlled based on the comparison result, the touch pressure can always be adjusted to an appropriate value.

Embodiment 2 This embodiment is an injection cylinder (A2) of an example of an injection device according to the "claim 2" of the present application, and is the same as the injection cylinder of Embodiment 1 except that the configuration is changed as shown in FIG. Therefore, the same members as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

That is, the injection cylinder (A2) of this example is shown in FIG.
As shown in FIG. 3, a cylindrical tip member (112) is provided on the outer circumference of the tip block body (111) formed at the tip of the heating cylinder (1).
Is configured to be detachable by screwing.

The front end member (112) has an opening edge (112a) at the front end protruding inward to form a narrowed opening (112b). A void is formed between the opening edge (112a) of the tip member (112) and the tip surface of the heating cylinder (1), and the nozzle (N2) and the load cell (L2) are formed in this void. It is stored. The nozzle (N2) is a flange around the body as in the first embodiment.
(N2a) is formed, and the size of this flange (N2a) is set so that it can be inserted into the void in the tip member (112).

The load cell (L2) is a donut shape through which the body of the nozzle (N2) is inserted, and its outer periphery is adjusted to a size that can be inserted into a void in the tip member (112). . The load cell (L2) is configured to be able to detect the compression strain, and its detection signal is output to the control unit.

Injection cylinder configured as described above
If the electric injection molding machine similar to that of the first embodiment is constructed by using (A2), the resin pressure control in the injection step is as follows, for example. That is, in the injection process, the heating cylinder (1)
The resin melted and kneaded inside is injected through the nozzle (N2), but at this time, the resin pressure applied to the nozzle (N2) presses the load cell (L2) in the injection direction, and the load cell (L2)
By itself, it will press the open end edge (112a) of the tip member (112), and eventually a compressive force will act on the load cell (L2). A signal corresponding to the strain (load) of the load cell due to this compressive force is output to the control unit (4) and compared there with a set value.

At this time, if the signal value is smaller than the set value, the control unit outputs the signal to the injection servomotor and increases its rotation speed until it becomes equal to the set value, whereby the nozzle (N2)
Command to increase the resin pressure applied to. If the signal value is larger than the set value, the control unit outputs it to the injection servo motor to reduce its rotation speed so that it becomes equal to the set value, thereby reducing the resin pressure applied to the nozzle (N2). Send an operation command. As described above, the resin pressure in the injection step is controlled to be substantially constant, and an injection-molded product having a substantially uniform density can be obtained.

Embodiment 3 This embodiment is an injection cylinder (A3) of another example of the injection device according to the "claim 2" of the present application, and is the same as embodiment 2 except that the configuration is changed to that shown in FIG. Therefore, the same members as those in the second embodiment are designated by the same reference numerals, and the description thereof will be omitted.

That is, the injection cylinder (A3) of this example is shown in FIG.
As shown in FIG. 4, the load cell (L3), the tip member (113) and the flange (N3a) of the nozzle (N3) have a structural relationship as shown in the figure, and the load cell (L3) is provided with a plurality of insertion holes. Use the screws (15) (16) to insert the tip member through the insertion hole
(113) and flange (N3a).

According to this structure, in the injection process,
When the resin melted and kneaded in the heating cylinder (1) is injected through the nozzle (N3) as in Example 2, the resin pressure applied to the nozzle (N3) presses the load cell (L3) in the injection direction, The load cell (L3) itself presses the opening end edge (113a) of the tip member (113), and eventually, the load cell (L3) is subjected to compressive strain due to the compressive force. Therefore, a signal corresponding to the compressive strain (load) of the load cell (L3) is output to the control unit, where it is compared with a set value, and the injection servomotor is drive-controlled based on this.

When the nozzle is touched, the nozzle (N3) comes into contact with the sprue of the mold and is pushed by it, and the screw (15) and the screw (15)
Since forces in opposite directions are applied to (16), shear strain occurs in the load cell (L3). Therefore, the load cell
The shear strain generated in (L3) is also detected, and a shear strain signal corresponding to the pressing force at the time of touching the nozzle is output to the control unit and an appropriate pressing value set in advance there (may be in an appropriate range. ), The nozzle touch pressure can always be adjusted to an appropriate value by controlling the drive of the injection servomotor based on the comparison result.

[0045]

According to the inventions of "Claim 1" and "Claim 2", the resin pressure applied to the nozzle in the injection process is detected as the strain generated in the load cell.
Based on this, the resin can be controlled to a desired resin pressure for injection, so that an injection-molded product having a uniform density can be obtained by using it in an injection molding machine.

Further, in any of the inventions according to "Claim 1" and "Claim 2" of the present application, the nozzle touch pressure can be set to an appropriate value or range.

Further, any of the inventions according to "Claim 1" and "Claim 2" of the present application can be carried out by slightly modifying the conventional injection cylinder, and have a simple structure. It is possible to exert a great technical effect that the density of molded products can be controlled.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of essential parts of an electric injection molding machine having an injection device according to the present invention.

FIG. 2 is a schematic cross-sectional view of an essential part of an example of an injection device according to “Claim 1” of the present application.

FIG. 3 is a diagram corresponding to FIG. 2 showing an example of an injection device according to the “claim 2” of the present application.

FIG. 4 is a view corresponding to FIG. 3 of another example of the injection device according to the “claim 2” of the present application.

[Explanation of symbols]

(M) ... Injection molding machine (A1), (A2), (A3) ... Injection cylinder (1) ... Heating tube (2) ... Screw (3) ... Drive transmission unit (4) ... Control unit (L1), (L2), (L3) ... Load cell (N1), (N2), (N3) ... Nozzle (3a) ... Rotation drive transmission part (3b) ... Injection drive transmission unit (3a1)… Servo motor for screw rotation (3b1) ... Servo motor for injection (3b2) ... Rotary support member (11)… Heating cylinder tip block (112), (113) ... Tip member

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B29C 45/00-45/84

Claims (2)

(57) [Claims] 1. A heating cylinder having a heater capable of kneading / melting / injecting resin in cooperation with a screw; and a nozzle provided at a tip of the heating cylinder, the nozzle being outside the nozzle and the nozzle. A load cell is interposed between the heating cylinder and the load cell is fixed to the heating cylinder, and by fixing the nozzle to the load cell, the resin pressure in the heating cylinder exerted on the nozzle is reduced in the strain generated in the load cell. An injection device configured to detect based on 2. A heating cylinder having a heater capable of kneading / melting / injecting a resin in cooperation with a screw, a nozzle housed in the tip of the heating cylinder, and a tip of the heating cylinder in the heating cylinder. And a load cell interposed between the nozzle and the heating cylinder and held in the heating cylinder, and configured to detect the resin pressure in the heating cylinder exerted on the nozzle based on the strain generated in the load cell. Injection device.