JPH0529852Y2 - - Google Patents

Description

[Detailed description of the invention] (Technical field) The present invention converts the rotational force of an electric servo motor into linear power using a screw feed mechanism, and applies the linear power to a moving object. The present invention relates to a servo drive mechanism for an injection molding machine that performs linear motion, and particularly to a servo drive mechanism that has good positioning accuracy for a moving object and can maintain that positioning accuracy well over a long period of time. It is something.

(Background Art) In injection molding machines, the rotational force of an electric servo motor has conventionally been used to drive a screw feed mechanism in order to eject an ejector pin in a mold clamping device or move an injection screw forward or backward in an injection device. A servo drive mechanism is used that converts linear power into linear power.

Therefore, in conventional servo drive mechanisms for moving moving objects such as ejector pins and injection screws, the rotational force of an electric servo motor was transmitted to the screw feed mechanism via a timing belt. . Therefore, in conventional servo drive mechanisms, there is a problem that the timing belt stretches and wears due to long-term use, resulting in a decrease in the positioning accuracy of moving objects such as ejector pins and injection screws. In order to prevent this, the servo drive mechanism had to be disassembled and the troublesome timing belt conversion work had to be carried out relatively frequently.

On the other hand, in order to solve this problem, the nut member of the screw feeding mechanism is attached to the moving object, and the male screw member of the screw feeding mechanism is connected to the electric servo motor, and the moving object is connected to the screw feeding mechanism. It is conceivable to move it directly through the In this case, since the accuracy of the screw feeding mechanism directly affects the positioning accuracy of the moving object, there is an inherent problem that it is extremely difficult to set the positioning accuracy of the moving object to a high level. .

(Problem to be solved) The present invention was developed against the background of the above, and its objective is to obtain a positioning accuracy for a moving object that is superior to the accuracy of the screw feeding mechanism. An object of the present invention is to provide a servo drive mechanism that can maintain positioning accuracy better over a long period of time than a conventional servo drive mechanism that uses a timing belt.

(Solution Means) In order to solve this problem, in the present invention, the rotational force of an electric servo motor is transmitted by a screw feed mechanism having a structure in which a nut member is screwed into a male screw member as described above. In a servo drive mechanism for an injection molding machine, which converts the power into linear power and applies it to a predetermined moving object to cause the moving object to move linearly based on the rotational force of the electric servo motor, the screw feeding mechanism and A link member rotatably supported around one axis is interposed between the object to be moved, and the male screw member of the screw feeding mechanism is connected to the electric servo motor. The nut member screwed into the male screw member is caused to move linearly in the axial direction based on the rotational operation, and the nut member is moved at a position a certain distance away from the rotation axis of the link member. connected to the link member so that the link member can rotate about the rotation axis by linear movement of the nut member in the axial direction;
The object to be moved is connected to the link member at a portion between the connection portion with the nut member and the rotation axis, so that the object to be moved is rotated about the rotation axis of the link member. According to the movement of the nut member, the nut member is guided by a predetermined guide means and is caused to move linearly in a direction parallel to the direction of movement of the nut member.

(Function) In such a servo drive mechanism, if the nut member of the screw feeding mechanism and the link member, and the link member and the moving object are connected with good accuracy, positioning errors of the moving object can be eliminated. , it can be considered that the error is due to the accuracy of the screw feeding mechanism. Here, the nut member and the link member of the screw feeding mechanism, and the link member and the object to be moved can be connected with a relatively simple structure and with sufficient accuracy.

By the way, in the present invention, the moving object is
Since the screw feed mechanism is connected to the link member at an intermediate point between the connection part with the nut member and the rotation shaft, as mentioned above, the positioning error of the moving object is caused solely by the error caused by the accuracy of the screw feed mechanism. If the nut member of the screw feeding mechanism and the link member, and the link member and the moving object are both connected with good accuracy, the nut member of the link member can be connected from the rotation axis of the link member to the link member. If the distance to the connecting part with the link member is _l1 , and the distance from the rotation axis of the link member to the connecting part of the link member with the moving object is _l2 , then the amount of movement of the moving object: B
is approximately l ₂ /l ₁ times the amount of movement of the nut member: A.
Therefore, if the positioning error of the screw feed mechanism is a, then the positioning error of the moving object: b is approximately l ₂ /l ₁ times the positioning error of the screw feed mechanism: a, and l ₁ > l ₂
Since, the positioning error of the moving object is:
b is the positioning error of the screw feeding mechanism: compared to a,
It becomes small enough.

In other words, according to the servo drive mechanism according to the present invention, the nut member and the link member of the screw feeding mechanism, and the link member and the moving object are both connected with good precision, thereby improving the accuracy of the screw feeding mechanism. In comparison, the positioning accuracy of the moving object can be significantly improved, and as mentioned above, the nut member and link member of the screw feeding mechanism, and the link member and the moving object are both relatively simple. Since the structure allows connection with good accuracy, the positioning accuracy of the moving object can be greatly improved compared to the case where the moving object is directly moved via a screw feeding mechanism.

In addition, in the servo drive mechanism according to the present invention, the power transmission mechanism between the electric servo motor and the moving object can be constructed using only rigid members, so the power transmission mechanism is more efficient than the conventional servo drive mechanism that uses a timing belt. Durability can be greatly improved,
Therefore, the positioning accuracy of the moving object can be maintained better for a longer period of time than in the conventional servo drive mechanism using a timing belt.

Furthermore, in the servo drive mechanism according to the present invention, since the link member constitutes a kind of deceleration mechanism, the electric servo motor can be advantageously made smaller compared to the case where the moving object is directly moved via the screw feed mechanism. It can also be converted into

(Examples) Hereinafter, in order to clarify the present invention more specifically, some examples thereof will be described in detail based on the drawings.

First, FIGS. 1 and 2 show an example in which the present invention is applied to an ejector pin protrusion mechanism in a mold clamping device of an injection molding machine. In those figures, reference numeral 10 denotes a movable plate for opening, closing, and pressing the mold between a fixed plate (not shown), and is supported by stays 12 inserted into the four corners. 12, so that it can move in the left and right directions in FIG. Further, in those figures, 14 is a guide plate whose four corners are slidably supported by stays 12, similar to the movable platen 10, and which holds the ejector box 16 between it and the movable platen 10. , can be moved in the horizontal direction in FIG. 1 integrally with the movable platen 10. Although not shown here, a predetermined driving means is connected to the guide plate 14, and this driving means drives the guide plate 14.
By integrally moving the movable platen 10 in the left-right direction in FIG. 1, opening/closing and clamping operations of the mold are performed between the movable platen 10 and a fixed platen (not shown).

Note that the guide plate 14 is here attached to the movable platen 10 with four bolts 18 arranged so as to surround the ejector box 16. In addition, the movable platen 10 and the guide plate 1
4 are slidably fitted to each stay 12 via sliding bushes 19 provided thereon.

Here, the ejector box 16 held between the movable platen 10 and the guide plate 14 has a cross-shaped notch 20 formed at a predetermined depth from the end face on the movable platen 10 side. , a movable platen 10 is placed in the notch 20 of this ejector box 16.
A cross-shaped ejector bar 22 is loosely fitted in parallel to the movable platen 10 so as to be movable a predetermined distance in the direction of movement. Then, an appropriate number of ejector pins 24 (in this case, five) as objects to be moved are erected on the ejector bar 22, with the ejector pins 24 protruding into the respective corresponding through holes 23 formed in the movable platen 10. It is set up. Furthermore, as is well known, these ejecta pins 2
A bolt or pin of the required length is connected to the tip of 4 by screwing, and the end surface of the connected bolt or pin is connected to the ejector mechanism of the movable mold attached to the movable platen 10. It will be forced to act.

The ejector bar 22 is loosely fitted into the notch 20 of the ejector box 16, and its cross-shaped arm portions 22a, 22a and 22b, 22b are all connected to the ejector box 1.
It is made to protrude laterally from 6. The ejector bar 22 includes an arm portion 22b that protrudes sufficiently from the ejector box 16;
22b, the guide plate 1 is connected from the movable platen 10 via the sliding bushes 28, respectively.
4 and are fitted into guide pins 26, 26 extending parallel to the moving direction of the movable platen 10,
Thereby, the movable platen 10 is guided by the guide pins 26, 26, and can be translated in a direction parallel to the moving direction of the movable platen 10. In other words, the ejector pin 24 as a moving object is guided in the axial direction by the guide pins 26, 26, and as is clear from this, here, the ejector bar 22
The guide pins 26, 26 that guide the guide constitute the guide means.

A cushion 30 is disposed at the base of the guide pins 26, 26, respectively, and a stopper 32 and a cushion 34 are disposed at the tips of the guide pins 26, 26, respectively, in an overlapping state. has been done. As a result, further forward movement of the ejector bar 22 is prevented based on the abutment of the guide pins 26, 26 against the cushions 30, 30 provided at the bases of the guide pins 26, 26, and the guide pins 26, 26 are prevented from moving further forward. Based on the contact with cushions 34, 34 provided at the tips of the ejector bars 26, 26, further rearward movement of the ejector bar 22 is prevented.

On the other hand, the arm portion 22a of the ejector bar 22,
Grooves 36, 36 having a constant width and extending parallel to the arm portions 22b, 22b are formed in the distal end surface of the groove 22a. The lever 38 as a link member is attached to the lever 38 as a link member in the grooves 36, 36 of the arm portions 22a, 22a of the ejector bar 22 so as to be able to slide with sufficient precision against both walls of the corresponding groove 36. The cam followers 40, 40 are inserted and fitted in parallel with the arm portions 22a, 22a and coaxially with each other.

As shown in FIG. 2, the lever 38 to which the cam followers 40, 40 are attached is connected to a pair of arm portions 38b, 38b from both ends of the connecting portion 38a.
have a U-shaped structure extending parallel to each other, and the arm portions 38b, 38b sandwich the arm portions 22a, 22a of the ejector bar 22 in the extending direction of the arm portions 22a, 22a, Further, the arm portions 38b, 38b are arranged in such a manner that they extend substantially parallel to the arm portions 22b, 22b of the ejector bar 22. As shown in the figure, the arm portion 2 of the ejector bar 22 is located at the tip of the arm portions 38b, 38b.
It is connected to the movable platen 10 via a bracket 44 that is connected to both ends of a rotating shaft 42 arranged parallel to the rotating shafts 2a and 22a and rotatably supports the rotating shaft 42.

Here, the arm portion 38 of such a lever 38 is shown in detail in FIG.
b, 38b, those arm portions 3
8a, 38b, parallel to the rotation axis 42, that is, the arm portion 22 of the ejector bar 22.
The cam followers 40, 40 are disposed so as to extend coaxially with each other and parallel to the arms 22a, 22a of the ejector bar 22, as described above.
Slideably enters the grooves 36, 36 at the tip of 2a.
As a result, as the lever 38 rotates around the rotation axis 42, the ejector bar 22 and, in turn, the ejector pin 24 are guided by the guide pins 26, 26, and the moving direction of the movable platen 10 is adjusted. It is designed so that it can be translated in a direction parallel to the .

The cam follower 40 has a structure in which the outer ring is rotatably held with high precision with respect to the shaft part, and the shaft part is attached to the arm parts 38b, 38b of the lever 38, and the outer ring is attached to the ejector bar. 22 arm parts 22a, 22a
The grooves 36, 36 are projected into the grooves 36, 36. By moving the outer ring within the grooves 36, 36, the lever 38 is allowed to rotate about the rotation axis 42.

Further, in FIG. 2, reference numeral 46 denotes a spacer interposed between bearings 48, 48 which rotatably hold the rotating shaft 42 on the bracket 44.

By the way, the arm portion 38 of the lever 38 moves the ejector bar 22 in parallel in a direction parallel to the moving direction of the movable platen 10 by rotating around the rotation shaft 42.
b, 38b, as shown in FIGS. 1 and 2, the cam followers 40, 40 have the same arrangement configuration as the cam followers 40, 40 at a portion closer to the connecting portion 38a. A pair of cam followers 50, 50 similar to the cam followers 40, 40 are provided. The cam followers 50, 50 are installed in grooves 54, 54 formed at both ends of the block 52 in the same manner as the grooves 36, 36 of the arm portions 22a, 22a of the ejector bar 22, similar to the cam followers 40, 40. , are slidably inserted into and fitted into both walls of the grooves 54, 54 with high precision.

Here, a ball screw nut 56 is attached to the block 52 in a state in which the axis thereof coincides with the direction of movement of the movable platen 10 at the center thereof. A ball screw 58 is screwed together. Here, the ball screw 58 screwed into the ball screw nut 56 is rotatably held by the movable platen 10 at one end, and mounted on the guide plate 14 via the coupling ring 60 at the other end. It is directly connected to a motor shaft 64 of an electric servo motor 62.

In other words, when the ball screw 58 is rotationally driven by the electric servo motor 62, due to the screw feeding action between the ball screw 58 and the ball screw nut 56,
The ball screw nut 56 and the block 52 to which the ball screw nut 56 is attached are the movable platen 1.
The block 5 is translated in parallel in the moving direction of 0.
As the lever 2 moves, the lever 38 is rotated about the rotation shaft 42. As described above, the ejector bar 22 is rotated based on the rotation of the lever 38 around the rotation axis 42.
is moved parallel to the moving direction of the movable platen 10, and the ejector pin 24 attached to the ejector bar 22 is moved relative to the movable platen 10 in the direction of their axes. Therefore, the ejector mechanism of the movable mold is driven. As is clear from this, here,
The ball screw 58 and the ball screw nut 56 are
They constitute the male screw member and nut member of the screw feeding mechanism, respectively.

In the figure, 66 is a spacer for attaching the electric servo motor 62 to the guide plate 14, and 68 is a spacer for detecting the amount of rotation of the electric servo motor 62 to detect the relative position of the ejector pin 24 with respect to the movable platen 10. It is a rotary encoder for Further, 70 and 72 are brackets 74 attached to the ejector bar 22, respectively.
This is a proximity switch for detecting the forward limit position and backward limit position of the ejector bar 22 by detecting the approach of the ejector bar 22, and when the ejector bar 22 moves beyond a preset stroke due to an abnormality in the controller that controls the electric servo motor 62, etc. This is to prevent further movement of the ejector bar 22 by, for example, blocking communication to the electric servo motor 62.

In the ejector pin 24 ejection mechanism having such a structure, as described above, the rotational force of the electric servo motor 62 is converted into linear motion of the ball screw nut 56 by the screw feeding action of the ball screw 58 and the ball screw nut 56. , the linear movement of the ball screw nut 56 causes the cam follower 50,
50 into a rotational movement of the lever 38 about the rotational axis 42. The rotational movement of this lever 38 around the rotational shaft 42 causes the cam followers 40, 4
0, the ejector bar 22 is converted into a linear movement, and in turn, the ejector pin 24 erected on the ejector bar 22 is converted into a linear movement in the axial direction.

Therefore, as is clear from this, the positioning error of the ejector pin 24 as a moving object depends on the accuracy of the screw feeding mechanism consisting of the ball screw 58 and the ball screw nut 56, and the accuracy of the ball screw nut 56 (via the cam followers 50, 50). This occurs due to a connection error between the block 52) and the lever 38, and a connection error between the lever 38 and the ejector bar 22 via the cam followers 40, 40.

Here, in this embodiment, as described above, the cam followers 50, 50 are connected to the grooves 5 at both ends of the block 52.
4, 54, and cam follower 4.
0,40 is the arm portion 22 of the ejector bar 22
Since the grooves 36 and 36 of grooves a and 22a are inserted into and fitted into both walls with high precision, there is no possibility of connection error between the ball screw nut 56 and the lever 38 via the cam followers 50, and the cam follower. Errors in the connection between the lever 38 and the ejector bar 22 via the levers 40 and 40 are extremely small, and therefore the positioning error of the ejector pin 24 is solely due to the accuracy of the screw feeding mechanism consisting of the ball screw 58 and the ball screw nut 56. It can be seen as something that occurs when

By the way, in this embodiment, as described above, the ball screw nut 56 (block 52) connects the lever 38 to the lever 38 at a portion farther from the rotation shaft 42 than the connecting portion of the ejector bar 22 to the lever 38.
is connected to. Therefore, the distance from the axis of the rotation shaft 42 of the lever 38 to the axis of the cam followers 50, 50 is l ₁ , and the distance from the axis of the rotation shaft 42 to the axis of the cam followers 40, 40 is l _2. Then, the amount of movement of the ejector bar 22, that is, the amount of movement of the ejector pin 24 as a moving object: B
is the amount of movement of the ball screw nut 56 that is moved based on the screw feeding action of the screw feeding mechanism: A
_Therefore , if the positioning error of the screw feeding mechanism consisting of the ball screw 58 and the ball screw nut 56 is _a , then the positioning error of the ejector pin 24 (ejector bar 22):b is also the positioning error of the screw feeding mechanism: It becomes l ₂ /l ₁ times of a.

Here, since l ₂ is sufficiently smaller than l ₁ , the positioning error b of the ejector pin 24 is sufficiently smaller than the positioning error a of the screw feed mechanism. For example, if l ₁ = 2l ₂ In this case, the positioning error of the screw feed mechanism: 1/2 error of a (2
Therefore, the moving position of the ejector pin 24 can be determined with twice the accuracy.

As described above, in the ejector pin protruding mechanism of this embodiment, the positioning accuracy of the ejector pin 24 as a moving object erected on the ejector bar 22 is compared with the accuracy of the screw feeding mechanism consisting of the ball screw 58 and the ball screw nut 56.
Therefore, the positioning accuracy of the ejector pin 24 is improved compared to the case where the ball screw nut 56 of the screw feeding mechanism is directly attached to the ejector bar 22 and the ejector bar 22 (ejector pin 24) is directly moved via the screw feeding mechanism. can be significantly increased.

Further, in the ejector pin protruding mechanism of this embodiment, the rotational force of the electric servo motor 62 is applied to the ball screw 58, the ball screw nut 56, the block 52, the cam followers 50, 50, the lever 38, and the cam follower 4, all of which are made of rigid materials.
0,40 to the ejector bar 22, the durability of the power transmission mechanism is significantly superior to that of conventional servo drive mechanisms that use timing belts. It is possible to maintain excellent positioning accuracy of the ejector pin 24 for a longer period of time than with a conventional servo drive mechanism using a conventional servo drive mechanism.

Furthermore, in the ejector pin protrusion mechanism of this embodiment, the lever 38 constitutes a kind of deceleration mechanism, and the linear power applied to the ball screw nut 56 is multiplied by approximately l ₁ /l ₂ and applied to the ejector bar 22. Therefore, ball screw 5
Compared to the case where the ejector bar 22 is directly moved via a screw feeding mechanism consisting of a ball screw nut 56 and a ball screw nut 56, the electric servo motor 62 can be advantageously miniaturized.

Next, an example in which the present invention is applied to a servo drive mechanism for moving the injection screw of an injection device forward and backward will be described in detail with reference to FIGS. 3 to 5.

That is, in FIGS. 3 to 5, 80
is a bearing box that rotatably supports the injection screw as a moving object, and as shown in FIG. It is supported immovably in the axial direction.

The screw connecting shaft 86 supported by the bearing box 80 has a screw connecting portion 88 at its front end, as shown in FIG. (not shown) are adapted to be connected at their proximal ends. In addition, this screw connecting shaft 8
6 is formed with a bottomed hole 90 that opens at the rear end surface, and a spline nut 92 is fixedly installed in this bottomed hole 90. The front end is inserted into the bottomed hole 90 of the screw connecting shaft 86, and is spline-fitted to a spline nut 92 by a spline formed at the front end.
A spline shaft 94 is provided.

This spline shaft 94 is for rotatably operating the injection screw while allowing movement of the injection screw connected to the bearing box 80 and eventually the screw connection shaft 86 in the axial direction. As shown, it is coaxially connected at its rear end to a rotating shaft 100 of a pulley 98 that is rotatably supported by a housing 96 of the injection device. As shown in FIG. 4, this pulley 98 and housing 96
A timing belt 106 is stretched between a pulley 104 attached to the output shaft of an electric servo motor 102 mounted in , which in turn is transmitted to the injection screw.

As is well known, the electric servo motor 102 is used to rotate the injection screw when plasticizing the resin material.
In FIG. 5, 107 is a strain block equipped with a strain gauge, which detects the force exerted from the injection screw via the screw connection shaft 86, thrust bearing 84, and adapter 109, and detects the injection pressure. It is used to detect such things as

By the way, as shown in FIGS. 3 to 5, the bearing box 80 has a pair of arm portions 80a, 80a extending left and right, and each of the arm portions 80a, 80a has a pair of arm portions 80a, 80a. It is slidably supported by a pair of guide rods 110, 110 supported by the housing 96 via sliding bushes 108, 108. The bearing box 80 is thus guided by the guide rods 110, 110 and can be moved in the axial direction of the injection screw. In other words, this allows the injection screw to be moved in the direction of its axis, and as is clear from this,
Here, these guide rods 110, 110 constitute guide means. Note that the guide rods 110, 110 each have their front ends connected to the housing 96, as shown in FIG.
and the rear end thereof to the front wall 96a of the housing 9.
The housing 96 is supported by the rear wall 96b of the housing 96.

On the other hand, the bearing box 80 has the arm portion 80 extending symmetrically upwardly and downwardly.
A pair of extension parts 80b, 80b different from a, 80a
are provided, and these extending portions 80b, 80b
grooves 1 of a constant width extending in a direction perpendicular to the axis of the injection screw, each opening at the tip surface of the injection screw.
12, 112 are formed. In these grooves 112, 112, grooves 112, 11 are formed.
Able to slide with high precision against both walls of 2.
Cam followers 116, 11 similar to those in the above embodiment attached to a lever 114 as a link member
6 are inserted and fitted together coaxially.

The lever 114 as a link member has a U-shaped structure in which a pair of arm members 118, 118 parallel to each other are connected to both ends of a connecting member 120 at one end. The arm members 118, 118 sandwich the extending portions 80b, 80b of the bearing box 80 in their extending direction, and the arm members 118, 118 are connected to the arm portions 80a, 80a of the bearing box 80. They are arranged in such a way that they extend almost parallel to each other. Similarly to the lever 38 in the embodiment described above, the arm members 118, 1
At the other end side of 18, a bearing box 80
The rotating shaft 122 is connected to a rotating shaft 122 arranged parallel to the extending direction of the extending portions 80b, 80b.
Bracket 124, 1 rotatably supports 22.
It is connected to the housing 96 via 24.

And the cam follower 40, 40 of the above embodiment
Similarly, in the intermediate portion of the arm members 118, 118 of such a lever 114, the cam follower 116, 116 is disposed, and the cam followers 116, 116 disposed in this way with respect to the lever 114, as described above,
Extensions 80b, 80b of bearing box 80
The grooves 112, 112 are slidably inserted and fitted into the grooves 112, 112.

In other words, in this embodiment, when the lever 114 is rotated around the rotation axis 122, the bearing box 80 and, by extension, the injection screw connected to the screw connecting shaft 86 of the bearing box 80 are rotated by the amount of rotation of the lever 114. Accordingly, the injection screw can be moved in the axial direction of the injection screw.

In addition, in FIG. 4, 126 is the rotation shaft 12.
This is a spacer interposed between bearings 128, 128 which rotatably hold 2 in brackets 124, 124.

Here, the lever 114 to which the cam followers 116, 116 are attached is located at a location farther from the rotation shaft 122 than the attachment location of the cam followers 116, 116, similar to the lever 38 of the embodiment described above. The cam follower 50, 5 of the above embodiment has the same arrangement form as 116.
Cam followers 130, 130 corresponding to 0 are provided. And these cam followers 13
0,130 are the grooves 112 of the extending portions 80b, 80b of the bearing box 80, as in the previous embodiment.
In the grooves 132, 132 formed at both ends of the block 131 in the same form as 112, grooves 13 are formed.
2,132 so that it can slide with high precision.

In this example, similarly to the previous example,
A ball screw nut 134 as a nut member is disposed in the center of the block 131, and a ball screw 140 as a male screw member screwed into the ball screw nut 134 is rotatable on the rear wall 96b of the housing 96 at its rear end. and at its front end, the housing 9
Electric servo motor 1 mounted on the front wall 96a of 6
36 via a coupling ring 138, and is arranged parallel to the axis of the injection screw.

That is, when the electric servo motor 136 rotates the ball screw 140, the ball screw nut 134 rotates around the ball screw 140, as in the above embodiment.
The lever 114 is moved in the axial direction of the rotation axis 1.
22, the bearing box 80 and, by extension, the injection screw as a moving object are moved in the direction of its axis.

In addition, in FIG. 3, 142 is a rotary encoder for detecting the amount of rotation of the electric servo motor 136 and detecting the moving position of the injection screw. Further, in FIG. 3, reference numeral 144 is a stopper fitted to both ends of each of the guide rods 110, 110, which abuts against the bearing box 80 and mechanically prevents unnecessary forward movement and backward movement. A cushion 146 for cushioning is provided at each tip. Furthermore, in FIG. 3, 148 and 150 are plates 152 and 154 fixed to the bearing box 80, respectively.
156 is a proximity switch for detecting the approach of the injection screw to detect the forward limit position and the backward limit position of the injection screw, and 156 is an indicator for visually confirming the movement position of the injection screw from outside the housing 96. Also, in Figure 4, 15
Reference numeral 8,158 is a guide bar that slidably supports the housing 96, and is used to move the injection device together with the housing 96 toward and away from the mold clamping device.

In such an injection device, a positioning error of the bearing box 80 and, by extension, a positioning error of the injection screw as a moving object is caused by the positioning error of the ball screw 140 and the ball screw nut 134, similar to the positioning error of the ejector bar 22 in the above embodiment.
The accuracy of the screw mechanism consisting of the ball screw nut 134 via the cam followers 130,
(block 131) and the connection error between lever 114,
This also occurs due to a connection error between the lever 114 and the bearing box 80 via the cam followers 116, 116, but in this embodiment as well,
Similar to the above embodiment, the cam followers 130, 13
0 against both walls of the grooves 132, 132 at both ends of the block 131, and against the cam followers 116, 116.
are the extension parts 80b, 80 of the bearing box 80.
Since the injection screw (bearing box 80) is inserted into and fitted into both walls of the grooves 112 and 112 with high precision, the positioning error of the injection screw (bearing box 80) is caused exclusively by the ball screw 140 and the ball screw nut 134. This can be considered to be caused by the accuracy of the screw feeding mechanism.

Therefore, similarly to the embodiment described above, the cam followers 130, 1
If _{the distance from the axis of the rotating shaft 122 to the axis of the cam followers 116, 116 is l 1 ,} then the positioning error of the injection screw: b is the positioning error of the screw feeding mechanism. :a's l ₂ /
l ₁ , and the positioning accuracy of the injection screw can be greatly improved compared to a case where the bearing box 80 is directly moved via a screw feeding mechanism.

Also in this embodiment, the ball screw 140, ball screw nut 134, block 131, cam followers 130, 130, lever 114, cam followers 116, 116 convert the rotational force of the electric servo motor 136 into linear power and transmit it to the bearing box 80. The injection screw (bearing box 80)
It has the advantage of being able to maintain good positioning accuracy over a long period of time.

Furthermore, as in the previous embodiment, since the lever 114 constitutes a kind of deceleration mechanism, the ball screw 1
40 and a ball screw nut 134, the electric servo motor 13
Another advantage is that 6 can be advantageously downsized.

Although several embodiments of the present invention have been described in detail above, these are literal illustrations, and the present invention is not limited to these specific examples, but may be applied within the scope of the invention. It goes without saying that the present invention can be implemented with various changes, modifications, improvements, etc. based on the knowledge of the vendor.

(Effects of the invention) As explained above, if the servo drive mechanism according to the invention is adopted as the ejector pin ejection mechanism of the mold clamping device in an injection molding machine, the injection screw moving mechanism of the injection device, etc., the ejector pin and injection screw The positioning accuracy of moving objects such as ejector pins and injection It is possible to maintain good positioning accuracy for moving objects such as screws over a long period of time, and the electric servo motor is advantageously smaller than when moving objects directly via a screw feed mechanism. It is possible to do so, and has excellent practical effects.

[Brief explanation of drawings]

FIG. 1 is an explanatory sectional view showing an example in which the present invention is applied to an ejector pin protrusion mechanism of a mold clamping device, and FIG. 2 is an explanatory partially cutaway cross-sectional view of FIG. 1. FIG. 3 is an explanatory cross-sectional view showing an example in which the present invention is applied to an injection screw moving mechanism of an injection device, FIG. , is an explanatory cross-sectional view showing an extracted bearing box in FIG. 3; 10...Movable plate, 14...Guide plate, 1
6... Ejector box, 22... Ejector bar, 24... Ejector pin (moving object),
26... Guide pin (guide means), 36, 54
...Groove, 38...Lever (link member), 40,
50...Cam follower, 42...Rotation axis, 52...
...Block, 56...Ball screw nut (nut member), 58...Ball screw (male thread member), 62
...Electric servo motor, 80...Bearing box, 86...Screw connection shaft, 96...Housing, 110...Guide rod (guide means),
112, 132... Groove, 114... Lever (link member), 116, 130... Cam follower, 1
22...Rotation axis, 131...Block, 134...
...Ball screw nut (nut member), 136...
Electric servo motor, 140...Ball screw (male thread member).

Claims (1)

[Claims for Utility Model Registration] A screw feed mechanism having a structure in which a nut member is screwed into a male screw member converts the rotational force of an electric servo motor into linear power and applies it to a predetermined moving object,
In a servo drive mechanism in an injection molding machine that causes the moving object to move linearly based on the rotational force of the electric servo motor, between the screw feeding mechanism and the moving object,
A link member rotatably supported around one axis is interposed, and the male screw member of the screw feeding mechanism is connected to the electric servo motor, and the male screw member is rotated based on the rotational operation of the electric servo motor. The nut member screwed onto the link member is moved linearly in the axial direction thereof, and the nut member is connected to the link member at a certain distance from the rotation axis of the link member. The link member is configured to be able to rotate around the rotation axis by linear movement in the axial direction of the nut member, and the object to be moved is connected to the connection portion with the nut member and the rotation axis. The object to be moved is guided by a predetermined guide means in accordance with the rotation of the link member about the rotation axis, so that the moving object is guided by a predetermined guide means in the direction of movement of the nut member. A servo drive mechanism for an injection molding machine, characterized in that it is capable of linear movement in a direction parallel to the .