JP3095996B2 - Linear actuator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear actuator for reciprocatingly driving a pair of piston rods by a hydraulic cylinder of a cylinder body.

[0002]

2. Description of the Related Art FIG.
0 is shown. This linear actuator 50 includes:
The cylinder body 51 is provided with a pair of cylinder chambers 52. A distal end of a piston rod 53 provided in each cylinder chamber 52 is connected by a connecting member 54, and the connecting member 54 is connected to a slide table 55. Therefore, the movable portion is constituted by the slide table 55, the connecting member 54, and the like. This linear actuator 50
For example, the work is carried by the connecting member 54 or the slide table 55, or the work is moved by the chuck attached to the connecting member 54.

[0003] A pair of holes 56 are formed in the connecting member 54, and the tip of each piston rod 53 is introduced into each hole 56. An engagement projection 57 having a small inner diameter is formed on the tip side of each hole 56, and an engagement portion 58 that engages with each engagement projection 57 is fixed to the tip of each piston rod 53. Therefore, the connecting member 54 is prevented from coming off from both piston rods 53 to the distal end side. Further, the stopper ring 5 is located slightly proximal to the distal end of each piston rod 53.
9 is fixed. A compression coil spring 60 for urging the connecting member 54 toward the distal end side with respect to the piston rods 53 is provided between each of the engagement convex portions 57 and each of the retaining ring portions 59.
Are interposed respectively. Therefore, in a state where the connecting member 54 does not apply a force to the work, the connecting member 54 is disposed on the distal end side of each piston rod 53.

For example, when the work is moved by the chuck attached to the connecting member 54 and the work is shifted from the normal position to the linear actuator 50 side, both the piston rods 53 are completely removed. Before the extension, the movement of the movable part is regulated. At this time, the compression coil springs 60 are contracted, so that the collision between the workpiece and the tool is buffered. As a result, the work and the linear actuator 50 are prevented from being damaged.

[0005]

However, in the above linear actuator 50, each piston rod 53 is
Each of the connecting members 54 is independently connected by a compression coil spring 60. Therefore, if there is any difference between the pressures applied to the piston rods 53, the piston rods 53 are driven separately without synchronization. as a result,
The connecting member 54 is not driven stably at a constant speed,
In some cases, it was not possible to carry the workpiece smoothly.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a linear actuator in which an operating member is driven by a plurality of piston rods extending and retracting in the same direction from a cylinder body. An object of the present invention is to provide a buffer function at the time of an abnormality and to stabilize the driving speed of the movable part.

[0007]

To solve the above problems SUMMARY OF THE INVENTION, the invention described in claim 1, and drives the operating member by a pair of piston rods which are infested from the cylinder body in the same direction, the operation member Can reciprocate to the cylinder body
In the linear actuator coupled to the guide member supported, the secure each tip of both piston rods to the supporting member, the operating member relative to the support member, said two piston
Was linked to the movement of the piston rod to the retractable direction at the connecting shaft in the middle of Tonroddo, further a compression coil spring that urges the operating member to the protruding side of both <br/> piston rod,
With the support member and the operation being performed while being inserted through the connection shaft,
It was interposed between members.

[0008]

According to a second aspect of the present invention, in the first aspect of the present invention, the operating member and the supporting member are preset in the operating member or the supporting member against the urging of the urging means. An approach detection sensor is provided for detecting that the vehicle has approached the specified distance.

Hereinafter, the operation of the invention described in each of the above claims will be described. According to the invention described in claim 1, since each tip of the pair of piston <br/> Tonroddo is fixed to the support member,
At the time of or immersion extending both piston rods, even if there is a difference in driving force acting on both the piston rod, both piston rods are driven in synchronism. As a result, the driving force applied to the operation member does not change. When the two piston rods are extended, the operating member connected to the support member is driven while being urged by the compression coil spring toward the projecting sides of the two piston rods. When the movement of the operating member is restricted, the operating member moves toward the support member against the urging force of the compression coil spring . Therefore, a force is applied from the support member to the operation member so as to gradually increase.

[0011] Further , since the guide member supported by the cylinder body so as to be reciprocally movable is connected to the operation member, rattling of the operation member and the guide member is prevented.

Further, a supporting member to which the pair of piston rods are fixed and an operating member are connected by a connecting shaft at the center of the pair of piston rods. Then, the operating member is urged to the projecting side by a compression coil spring interposed between the operating member and the supporting member in a state where the connecting shaft is inserted through the supporting member. Therefore, when the movement of the operation member is restricted, the reaction force is evenly applied to both the piston rods. As a result, the operation member is prevented from being twisted.

According to the second aspect of the present invention, the first aspect is provided.
In addition to the operation of the invention described in the above, the proximity detecting means for detecting that the operation member and the support member have approached to a preset distance at the time of buffering is provided, so that the buffering state can be detected. As a result, it is possible to reliably detect the occurrence of the buffer state.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. In this embodiment, for convenience of description, the upper side in FIGS. 1 and 2 will be described as the rear side of the linear actuator 1, the lower side will be the front side, the right side will be the right side, and the left side will also be the left side.

2 to 5 show a linear actuator 1 according to the present embodiment. As shown in FIG. 1, a pair of air cylinder chambers 3 and 4 extending in the front-rear direction are formed in the actuator body 2 as a cylinder body. Each air cylinder chamber 3, 4 has a piston 5,
6 are provided respectively. The air cylinder chamber 3 is partitioned by a piston 5 into a head-side piston chamber 7 and a rod-side piston chamber 8. Similarly, the air cylinder chamber 4
The piston 6 is partitioned into a head-side piston chamber 9 and a rod-side piston chamber 10. A head-side port 12 is connected to each head-side piston chamber 7, 9 via a flow path 11, and a flow path 13 is connected to each rod-side piston chamber 8, 10.
The rod-side port 14 is communicated via the.

A piston rod 15 is fixed to the piston 5, and the distal end of the piston rod 15 is led out of the air cylinder chamber 3 to the front outside of the actuator body 2. Similarly, a piston rod 16 is fixed to the piston 6, and a distal end side of the piston rod 16 is led out of the air cylinder chamber 4 to the front outside of the actuator body 2. Each tip of each of the piston rods 15, 16 is fixed to a support plate 17 as a support member.

As shown in FIGS. 2 to 4, a guide rail 18 extending in the front-rear direction is fixed to the upper surface of the actuator body 2. This guide rail 18 has a guide block 19 that slides on the guide rail 18.
The slide table 20 as a guide member is supported so as to be able to reciprocate in the front-rear direction via the.

As shown in FIGS. 5A and 5B, a connecting plate 21 as an operation member is fixed to the front end of the slide table 20. The lower part of the connection plate 21 is arranged at a position facing the support plate 17. In the linear actuator 1 of the present embodiment, the work W is pressed by the connecting plate 21.

A connecting shaft 22 having a columnar shape is fixed to the left and right centers of the rear surface of the connecting plate 21 so as to extend rearward. The distal end side of the connecting shaft 22 has a pair of piston rods 15,
The support plate 17 is inserted into the center of the support member 16 and is led out toward the actuator body 2. An engagement portion 23 that engages with the support plate 17 is provided at a tip of the connection shaft 22. Therefore, the connecting plate 21 and the supporting plate 17 are
Can be approached or separated from each other within a distance interval when the engaging portions 23 of the pair engage with the support plate 17.

Between the support plate 17 and the connecting plate 21, a compression coil spring 24 as an urging means is interposed with the connecting shaft 22 inserted therein. Compression coil spring 24
Urges the support plate 17 and the connection plate 21 to be separated from each other. Therefore, the support shaft 17 and the connection plate 21 are not connected to each other when no force is applied so as to approach each other.
It is held in a state of being separated by the distance interval determined in Step 2. In the present embodiment, the connection shaft 22 and the compression coil spring 24 constitute a buffer unit.

A sensor mounting portion 25 is provided on the right side surface of the connecting plate 21 and extends rearward in the front-rear direction.
A magnetic proximity sensor 26 as a deformation detection sensor is attached to the sensor mounting portion 25. On the other hand, the support plate 17
A magnet 27 is attached to the front surface of. The magnetic proximity sensor 26 detects the magnet 27 when the distance between the support plate 17 and the connecting plate 21 becomes a predetermined distance that is abnormally smaller than the distance determined by the connecting shaft 22.

On the left side of the actuator main body 2, a buffer 28 for extension is attached to a front portion thereof, and a buffer 29 for immersion is attached to a rear portion thereof. On the other hand, a contact portion 30 is provided on the left side surface of the slide table 20. The contact portion 30 contacts the immersion shock absorber 29 when the pistons 5 and 6 are disposed at the head-side ends of the air cylinder chambers 3 and 4, and when the pistons 5 and 6 are disposed at the rod-side ends. At the time of extension. Therefore, when the pistons 5 and 6 are moved forward and approach the rod-side end, the abutting portion 30 abuts on the buffer 28 at the time of extension to buffer the stop of the slide table 20. Conversely, when the pistons 5 and 6 are moved backward and approach the head-side end, the abutting portion 30 abuts on the buffer 29 during immersion to buffer the stop of the slide table 20.

Next, the operation of the linear actuator configured as described above will be described. Head side port 1
When the air is supplied to 2 and the air is exhausted from the rod side port 14, both pistons 5, 6 are driven forward. At this time, since both piston rods 15, 16 are fixed to the support plate 17, each piston rod 15, 1
6 are driven synchronously.

At this time, since the cushioning mechanism is provided between the connecting plate 21 and the supporting plate 17, the mass of the movable portion including the connecting plate 21, the supporting plate 23, the connecting shaft 22, and the like is lighter than in the prior art. . Therefore, the connection plate 21 is quickly driven by the introduction and exhaust of air.

When the pistons 5, 6 are reciprocated between the rod-side end and the head-side end, the piston rods 15, 16 are reciprocated at a predetermined distance. This allows the connecting plate 21 or the slide table 20
, The work W is transported repeatedly.

As shown in FIG. 6, for example, before the two piston rods 15 and 16 extend to the maximum extent,
Comes into contact with the workpiece W, the piston rods 15, 16
The compression coil spring 24 is compressed and deformed with the extension. The reaction force due to the compression deformation of the compression coil spring 24 is applied from the connecting plate 21 to the work W as a pressing force. At this time, since the amount of compressive deformation of the compression coil spring 24 gradually increases, the pressing force applied to the work W gradually increases from zero. As a result, the collision between the workpiece W and the movable part is buffered.

At this time, since the compression deformation of the compression coil spring 2 is detected by the magnetic proximity sensor 26, the occurrence of the buffer state is detected. Further, at the time of buffering, the connecting shaft 22 supporting the compression coil spring 24 is connected to the pair of piston rods 15 and 1.
6, the reaction force of the compression coil spring 24 is applied to the piston rods 15, 16
Are added equally. As a result, the connection plate 21
And the slide table 20 is not twisted.

Further, when the cushion 5 is not cushioned,
When the rod 6 reaches the rod-side end, the contact part 30 comes into contact with the extension buffer 28, so that the movable part including the slide table 20, the connecting plate 21 and the like does not suddenly stop.
As a result, a force is not suddenly applied to the work from the movable portion, so that damage to the work is prevented.

As described in detail above, according to the linear actuator of the present embodiment, the following effects can be obtained. (A) Each end of a pair of piston rods 15 and 16 extending from the actuator body 2 is fixed to a support plate 17, and a compression coil spring 24 is interposed between the support plate 17 and the connection plate 21. Therefore, the piston rods 15, 1
Even when there is a difference in the driving force applied to each of the piston rods 15 and 16 when the 6 is driven, each of the piston rods 15 and 16 can be driven synchronously. As a result, the driving force applied to the connecting plate 21 does not fluctuate, so that the connecting plate 21 can be driven stably at a constant speed.

(B) A pair of piston rods 15, 16
The slide table 20 supported by the actuator main body 2 so as to be able to reciprocate is connected to the connection plate 21 driven by. Therefore, it is possible to prevent the connection plate 21 and the slide table 20 from rattling. As a result, the connecting plate 2
1 and the slide table 20 can be driven in a stable state, so that the work can be transported in a stable state.

(C) A pair of piston rods 15 and 16 fixed to the support plate 17 by connecting the support plate 17 and the connecting plate 21 to each other.
At the center with a connecting shaft 22. Then, a compression coil spring 24 was interposed between the support plate 17 and the connection plate 21 with the connection shaft 22 being inserted. Therefore, when the movement of the connecting plate 21 is restricted during buffering, each piston rod 15,
The reaction force is evenly applied to 16. As a result, the torsion of the connecting plate 21 due to the displacement of the two piston rods 15, 16 is prevented.
No excessive force is applied to the actuator body 2. For this reason, each of the piston rods 15 and 16
In addition, since abnormal wear of the actuator body 2 is prevented, the life of the linear actuator 1 can be extended.

(D) The magnetic proximity sensor 26 is connected to the connecting plate 21.
To detect the compression deformation of the compression coil spring 24 at the time of buffering. As a result, abnormalities in the work position can be reliably found.

(E) An extension shock absorber 29 is provided in the actuator body 2 to gradually reduce the speed of the movable portion including the slide table 20 immediately before the piston rods 15 and 16 extend to the maximum extent. Therefore, a force is not suddenly applied to the work from the movable portion, so that damage to the work can be prevented.

It should be noted that the present invention is not limited to the above-described embodiment, but may be configured as follows .

[0035]

(3) The support plate 17 and the connecting plate 21 are connected by one connecting shaft 22, but may be connected by two or more connecting shafts 22. Further, the connecting shaft 22 need not be inserted through the compression coil spring 24.

(4) The connecting shaft 22 is fixed to the connecting plate 21 so that the distal end is inserted into the supporting plate 17. Conversely, the connecting shaft 22 is fixed to the supporting plate 17 and the distal end is connected to the connecting plate. 21 may be inserted. Even in this case,
The mass of the movable part can be reduced.

[0038]

( 7) The magnetic proximity sensor 26 may not be provided. Even in this case, the linear actuator 1
Alternatively, damage to the work can be prevented.

Instead of the magnetic proximity sensor 26, CdS,
An optical sensor such as a photodiode may be used. In this case, it is not necessary to provide the magnet 27 having a relatively large volume on the support plate 17.

(8) The actuator body 2 may not be provided with the shock absorbers 28 and 29. Even in this case, it is possible to prevent the work W from being damaged by the pressing force. (9) Linear actuator 1 consisting of an air cylinder
However, the present invention may be applied to the linear actuator 1 including another hydraulic cylinder.

[0042]

[0043]

As described in detail above, according to the first aspect of the present invention, it is protruded and retracted from the cylinder body in the same direction.
In a linear actuator in which an operating member is driven by a pair of piston rods, a buffering function at the time of an abnormality is provided, and the driving speed of the movable portion can be stabilized. As a result, it is possible to prevent a shock from being applied to the work or the actuator at the time of an abnormality, and to transport the work in a stable state at the normal time.

[0044] Also, the guide member is reciprocally movable in the cylinder body, and, since it is possible to prevent rattling of the operating member, it is possible to transport the workpiece in a more stable state.

Furthermore, since abnormal wear of both piston rods and the cylinder body due to buffering can be prevented,
Life can be extended.

According to the second aspect of the invention, in addition to the effect of the first aspect of the present invention, the occurrence of a buffer state can be reliably detected, so that damage to the actuator or the work can be prevented. .

[Brief description of the drawings]

FIG. 1 is a plan sectional view of a linear actuator.

FIG. 2 is a plan view of the same.

FIG. 3 is also a rear view.

FIG. 4 is a front view of the same.

5A is a right side view of the same, and FIG. 5B is a cross-sectional view of FIG.

FIG. 6 is a plan sectional view showing an operation state.

FIG. 7 is a plan sectional view of a conventional linear actuator.

[Explanation of symbols]

2. Actuator body as cylinder body, 15,
16: piston rod, 17: support plate as support member, 20: slide table as guide member, 21 ...
A connecting plate as an operating member, 22 a connecting shaft, 24 a compression coil spring as an urging means, 26 a magnetic proximity sensor as a deformation detecting sensor.

Claims (2)

(57) [Claims] 1. A drive the operation member (21) in the cylinder body (2) a pair of piston rods which are infested in the same direction from the (15, 16), in its operating member (21), Siri
Guide member supported reciprocally by the cylinder body (2)
In the linear actuator coupled with (20), said secure each tip of both piston rods (15, 16) to the supporting member (17), the operating member relative to the support member (17) to (21), wherein both Piston rod (15, 1
6) At the center of the connecting rod (22) at the center of the piston rod (1 )
5 and 16) so as to be movable in the retreating direction, and further, the operation member (21) is connected to the two piston rods (15, 1).
6) The compression coil spring (24) biasing to the protruding side
The support member (1) is inserted through the connecting shaft (22).
7) A linear actuator interposed between the operating member (21) . 2. An operating member (21) or said support member (1).
7) is provided with an approach detection sensor (26) for detecting that the operation member (21) and the support member (17) have approached to a preset distance against the bias of the biasing means. The linear actuator according to claim 1 .