JP3552970B2 - Pressure detector for injection molding machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pressure detection device for an injection molding machine that detects a pressure applied to a movable part by interposing a load converter between a movable part side such as a screw and a drive mechanism side.
[0002]
[Prior art]
Conventionally, injection molding that detects a pressure applied to a movable part by interposing a load cell (load converter) between a drive mechanism side including a drive motor and a ball screw mechanism and a screw side driven forward and backward by the drive mechanism side. A pressure detector for a machine is known from Japanese Patent Publication No. 8-2567 and Japanese Patent Laid-Open No. 10-151653.
[0003]
This type of pressure detection device fixes one end surface of a load cell to a screw support member that supports a screw, and also fixes the other end surface of the load cell to a ball screw portion or a nut portion in a ball screw mechanism. A function of detecting a load applied between the portions or the nut portions is provided.
[0004]
[Problems to be solved by the invention]
However, the conventional pressure detection device provided in the above-described injection molding machine has the following problems.
[0005]
First, since the load converter (load cell) is fixed to both the screw support member and the ball screw mechanism by a fixing screw, unnecessary stress (load) in the rotation direction at the ball screw portion or the nut portion is directly applied. Only the pressure in the straight direction cannot be detected accurately and with high accuracy.
[0006]
Secondly, since the load converter serves as both a screw support member and a connecting member for the ball screw mechanism, it is easily affected by the heat generated in the periphery, resulting in a further decrease in accuracy and detection accuracy due to temperature drift. At the same time, maintenance becomes difficult, and in addition, problems such as accelerating the deterioration (lifetime) of the load converter are caused.
[0007]
The present invention solves such problems existing in the prior art, can eliminate unnecessary stress and temperature drift, and can stably perform accurate and high-accuracy pressure detection, and can be easily maintained. It is an object of the present invention to provide a pressure detection device for an injection molding machine that can improve and further extend the life of a load transducer.
[0008]
[Means for Solving the Problems and Embodiments]
In the present invention, a load converter is interposed between a drive mechanism 5 side including a drive motor 3 and a ball screw mechanism 4 and a movable part 2 side such as a screw 2s driven forward and backward by the drive mechanism 5 side. When the pressure detection device 1 of the injection molding machine M that detects the pressure applied to 2 is configured, the flange portion 6 is provided integrally with the nut portion 4n or the ball screw portion 4s of the ball screw mechanism 4, and the nut portion 4n or The ball screw portion 4 s is coupled to the movable portion 2 side from the pressurizing direction Hp via the pressure receiving washer 8, and the strain gauges 12 p and 12 q are provided on the inner peripheral surface of the ring member 11 to load from the deformation of the pressure receiving washer 8. The pressure applied to the movable part 2 is detected by mounting the ring member 11 in the load converter 9 for detecting the pressure on the outer peripheral surface of the pressure receiving washer 8. .
[0009]
In this case, according to a preferred embodiment, a pair of ball screw mechanisms 4 and 4 e can be provided on the left and right sides, and a load converter 9 can be provided on one or both of the ball screw mechanisms 4.
[0010]
As a result, when pressure is applied from the drive mechanism 5 or back pressure is applied from the movable part 2, pressure or back pressure is applied from the axial direction to the pressure receiving washer 8 interposed between the flange part 6 and the movable part 2 side. Is granted. As a result, the pressure receiving washer 8 is deformed in the axial direction in accordance with the magnitude of the applied pressure or back pressure, and the amount of deformation is detected by the load converter 9. That is, the deformation amount is detected by the strain gauges 12p and 12q provided on the inner peripheral surface of the ring member 11 attached to the outer peripheral surface of the pressure receiving washer 8, and the pressure applied to the movable portion 2 is detected based on this.
[0011]
【Example】
Next, preferred embodiments according to the present invention will be given and described in detail with reference to the drawings.
[0012]
First, the structure of the injection molding machine M provided with the pressure detection apparatus 1 according to the present embodiment will be described with reference to FIG.
[0013]
FIG. 1 shows a part of an injection device Mi (plan view), and an injection molding machine M is constituted by the injection device Mi and a mold clamping device (not shown). In the figure, 21 is an injection table, and 22 is an injection drive table, which are spaced apart from each other on the upper surface of the machine table (not shown), and there are four guide shafts 23 between the injection table 21 and the injection drive table 22. Are installed, and the slider 24 is slidably loaded on the guide shafts 23.
[0014]
In addition, the rear end of the heating cylinder 25 is fixed to the front surface of the injection table 21. The heating cylinder 25 includes a hopper 26 that supplies a molding material to the rear part, and a screw 2s (movable part 2) is inserted therein. On the other hand, the rear end of the screw 2s faces the back of the injection table 21, and is coupled to the front end of a screw coupling 31 that is rotatably supported at the center of the slider 24. In this case, the screw coupling 31 is supported by the slider 24 via bearings 27, 28, 29, and 30 as shown in FIG. On the other hand, a rotation transmission shaft 32 is rotatably supported via a bearing 33 at the center of the injection drive base 22. The rotation transmission shaft 32 protruding forward from the injection drive base 22 is splined to the rear end of the screw coupling 31, and the rotation transmission shaft 32 protruding rearward from the injection drive base 22 has a toothed surface. Install the driven pulley 34. The toothed driven pulley 34 is rotationally transmitted from a measuring servo motor 35 via a timing belt 36, and the screw 2s is rotationally driven.
[0015]
Further, a pair of left and right ball screw mechanisms 4, 4 e are disposed between the injection table 21 and the injection drive table 22. In this case, the ball screw portion 4 s of one ball screw mechanism 4 is rotatably mounted via a bearing between the injection table 21 and the injection drive table 22, and the nut portion 4 n of the ball screw mechanism 4 is provided on the slider 24. Join to the right side. Further, the ball screw portion 4es of the other ball screw mechanism 4e is rotatably mounted via a bearing between the injection table 21 and the injection drive table 22, and the nut portion 4en of the ball screw mechanism 4e is provided on the left side of the slider 24. To join. On the other hand, toothed driven pulleys 37 and 38 are attached to the rear ends of the ball screw portions 4s and 4es that protrude rearward from the injection drive base 22, respectively. The toothed driven pulleys 37 and 38 are rotationally transmitted via a timing belt 39 from an injection servomotor 3s (drive motor 3). The servo motor 3s and the ball screw mechanisms 4 and 4e constitute a drive mechanism 5 that drives the screw 2s forward and backward. And the pressure detection apparatus 1 which concerns on a present Example is arrange | positioned using one nut part 4n and the slider 24. FIG.
[0016]
Next, the configuration of the pressure detection device 1 according to the present embodiment will be described with reference to FIGS.
[0017]
The nut portion 4n described above has a cylindrical outer peripheral surface, and a large-diameter flange portion 6 shown in FIG. 2 is integrally provided at the rear end portion of the nut portion 4n. On the other hand, the slider 24 on the movable portion 2 (screw 2s) side is provided with an insertion hole 7 into which the nut portion 4n is inserted. Also, a pressure receiving washer 8 is prepared. The pressure receiving washer 8 has a constant thickness in the axial direction, and the inner diameter thereof substantially matches the inner diameter of the insertion hole 7. When the nut portion 4n is coupled to the slider 24, the nut portion 4n fitted with the pressure receiving washer 8 is inserted into the insertion hole 7 from the pressing direction Hp, and the flange portion 6 and the pressure receiving force are received by a bolt (not shown). The washer 8 is fixed, and the pressure receiving washer 8 is fixed to the slider 24 by a bolt (not shown). Thereby, the nut portion 4n is fixed in the rotational direction with respect to the slider 24, but is not fixed in the axial direction. The above coupling structure is the same on the nut portion 4en side.
[0018]
Furthermore, a load converter (strain sensor) 9 for detecting a load from deformation of the pressure receiving washer 8 is mounted on the outer peripheral surface of the pressure receiving washer 8 mounted on one nut portion 4n. As shown in FIG. 3, the load converter 9 has a ring member 11 attached to the outer peripheral surface of the pressure receiving washer 8, and includes strain gauges 12 p and 12 q on the inner peripheral surface of the ring member 11. The ring member 11 is composed of two divided ring halves 11p and 11q. After the ring halves 11p and 11q are mounted on the outer peripheral surface of the pressure receiving washer 8, the ring halves 11p and 11q are connected by fixing bolts 15 and 16. can do. Further, the strain gauges 12p and 12q are fixedly attached to the center in the circumferential direction of the inner peripheral surfaces of the ring halves 11p and 11q, and the strain gauges 12p and 12q are connected to the controller 17. The strain gauges 12p and 12q slightly protrude from the inner peripheral surfaces of the ring halves 11p and 11q. Therefore, the controller 17 can drive-control the servomotor 3s based on the detection results by the strain gauges 12p, 12q, and perform feedback control on the pressure.
[0019]
Next, the operation of the injection process in the injection molding machine M including the function of the pressure detection device 1 according to the present embodiment will be described with reference to each drawing.
[0020]
Now, it is assumed that the injection molding machine M is in a state where the weighing process has been completed. Accordingly, the screw 2s is located at the reverse injection start position. The servo motor 3s is driven and controlled by the controller 17 by the start of the injection process, and the rotation of the servo motor 3s is transmitted to the ball screw portions 4s and 4es of the ball screw mechanisms 4 and 4e. As a result, when the nut portions 4n, 4en, the slider 24 and the screw coupling 31 are integrally advanced, the screw 2s is also moved forward, and the resin measured in front of the screw 2s is injected into a mold (not shown). Filled.
[0021]
At this time, if the nut portion 4n moves forward, pressure is applied in the axial direction from the flange portion 6 to the pressure receiving washer 8 interposed between the flange portion 6 and the movable portion 2 side. Thereby, the pressure receiving washer 8 is deformed in the axial direction according to the magnitude of the applied pressure, and the amount of deformation is detected by the load converter 9. That is, the deformation amount is detected by the strain gauges 12p and 12q provided on the inner peripheral surface of the ring member 11 attached to the outer peripheral surface of the pressure receiving washer 8, and accordingly, the controller 17 detects the pressure corresponding to the deformation amount (movable part 2). ) Is detected. Therefore, the controller 17 drives and controls the servo motor 3s based on the detected pressure value, and performs feedback control on the applied pressure (injection pressure, holding pressure, etc.).
[0022]
In addition, although the operation | movement in an injection | emission process was demonstrated, in the measurement process, the back pressure from the screw 2s (movable part 2) can be detected similarly by the pressure detection apparatus 1.
[0023]
As described above, according to the pressure detection device 1 according to the present embodiment, the load transducer 9 mounted on the outer peripheral surface of the pressure receiving washer 8 has an unnecessary stress (load) in the rotation direction at the nut portion (ball screw portion). Is not directly applied, it is possible to accurately and accurately detect only the pressure in the straight direction. Further, the load converter 9 does not serve as a screw support member and a connection member for the ball screw mechanism as in the prior art, and in particular, since it is provided on one of the ball screw mechanisms provided on the left and right, the maintenance performance is improved. Can avoid the problem of accelerating the deterioration (lifetime) of the load transducer 9. In addition, since it is difficult to be affected by the heat generated in the peripheral portion, a decrease in accuracy and detection accuracy due to temperature drift is avoided.
[0024]
The embodiment has been described in detail above, but the present invention is not limited to such an embodiment, and the detailed configuration, shape, material, quantity, and the like can be arbitrarily set within the scope of the present invention. Can be changed, added or deleted. For example, although the screw 2s is illustrated as the movable part 2, the movable part 2 may be a mold clamping mechanism, an injection device itself, or the like. Moreover, although the case where the load converter 9 is disposed in one ball screw mechanism 4 of the pair of ball screw mechanisms 4 and 4e has been shown, The average value of the vessels 9 may be used, and even when a single ball screw mechanism is provided, the same can be implemented. Furthermore, although the embodiment shows a case where the nut portion 4n moves forward and backward, when the nut portion 4n rotates and the ball screw portion 4s moves forward and backward, for example, the tip shape of the ball screw portion 4s is changed to the nut portion 4n. If it is formed in the same shape as the outer shape of the flange portion 6, it can be similarly implemented.
[0025]
【The invention's effect】
As described above, the pressure detection device for an injection molding machine according to the present invention is provided with the flange portion integrally with the nut portion or the ball screw portion of the ball screw mechanism, and the nut portion or the ball screw portion is added via the pressure receiving washer. The ring member in the load converter that detects the load from the deformation of the pressure receiving washer by mounting the strain gauge on the inner peripheral surface of the ring member while being coupled to the movable portion side from the pressure direction is mounted on the outer peripheral surface of the pressure receiving washer. As a result, since the pressure applied to the movable part is detected, the following remarkable effects can be obtained.
[0026]
(1) Unnecessary stress (load) in the rotational direction at the nut part (ball screw part) is not directly applied to the load transducer attached to the outer peripheral surface of the pressure receiving washer, so only the pressure in the straight direction is accurately and highly accurate. Can be detected.
[0027]
(2) Since the load converter does not serve as a connecting member for the screw support member and the ball screw mechanism as in the prior art, it is not easily affected by the heat generated in the periphery, and the accuracy and detection accuracy are reduced due to temperature drift. While avoiding stable pressure detection, it is possible to improve maintenance, and contribute to extending the life of the load transducer.
[Brief description of the drawings]
FIG. 1 is a partial plan view of an injection device in an injection molding machine including a pressure detection device according to a preferred embodiment of the present invention;
FIG. 2 is a cross-sectional view showing an extracted pressure detection device provided in the injection device;
FIG. 3 is a partially sectional front view showing a load converter and a pressure washer of the pressure detection device;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Pressure detection apparatus 2 Movable part 2s Screw 3 Drive motor 4 Ball screw mechanism 4e Ball screw mechanism 4n Nut part 4s Ball screw part 5 Drive mechanism 6 Flange part 8 Pressure receiving washer 9 Load converter 11 Ring member 12p Strain gauge 12q Strain gauge M Injection molding machine Hp Pressure direction

Claims (3)

The pressure of the injection molding machine that detects the pressure applied to the movable part through a load converter between the drive mechanism side including the drive motor and the ball screw mechanism and the movable part side driven forward and backward by the drive mechanism side. In the detection device, a flange portion is integrally provided on the nut portion or the ball screw portion of the ball screw mechanism, and the nut portion or the ball screw portion is coupled to the movable portion side from the pressurizing direction via a pressure receiving washer. The pressure applied to the movable part by mounting the ring member in the load transducer that detects the load from the deformation of the pressure receiving washer by providing a strain gauge on the inner peripheral surface of the member. A pressure detection device for an injection molding machine, characterized in that The pressure detection device for an injection molding machine according to claim 1, wherein the movable part is a screw of an injection device. The pressure detection device for an injection molding machine according to claim 1, wherein a pair of the ball screw mechanisms are arranged on the left and right, and the load converter is arranged on one or both of the ball screw mechanisms.

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