JPH0634013A - Cam device - Google Patents

Abstract

PURPOSE:To reduce a maximum value of a pressure angle to a minimum in a cam device composed of radial cams and direct-acting driven nodes. CONSTITUTION:Radial cams 2a and 2b provided on a rotary shaft 1 respectively correspond to contacts 5a and 5b provided on a direct-acting driven node 4. The cam and contact of one pair has the same displacement characteristic. A line which passes the contact point of the cam 2a and the contact 5a, being parallel to the driven node movement is arranged symmetrically to a line which passes a contact point of the cam 2b and the contact 5b, being parallel to the driven node movement across the line which passes a center P of the rotary shaft 1, being parallel to the driven node movement.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cam device which is a mechanical element, and more particularly to a cam device which is composed of a radial cam attached to a rotary shaft and a linear end driven follower.

[0002]

2. Description of the Related Art The basic construction of a cam device composed of a radial cam and a linear end driven follower is shown in FIG. The radial cam 2 attached to the rotary shaft 1 moves in the direction of arrow X around P.
Driven to rotate. The linear driven follower 4 is regulated by the guide 3 and slides in the direction of the arrow Y. The roller contactor 5 attached to the lower end of the linearly driven follower 4 is in contact with the radial cam 2 by an appropriate biasing force, and the driven follower 4 linearly moves as the cam 2 rotates.

As is well known, the angle formed by the common normal line at the contact point between the cam surface and the follower contact and the movement direction Y of the follower 4 is called the pressure angle. The larger the pressure angle, the larger the main normal force at the contact point between the cam 2 and the contact 5, and the larger the force in the direction orthogonal to the movement direction of the driven joint 4 (prying force). Therefore, the contact pressure between the cam 2 and the contact 5 exceeds an allowable value, and the follower 4 is bent, so that the movement is not smooth. Therefore, the maximum value of the pressure angle should be minimized when designing the cam device.

[0004]

When designing a cam device, the first important thing is to achieve the desired motion characteristics, and the maximum value of the above-mentioned pressure angle must be made as small as possible. In the cam device as shown in FIG. 1, a line segment passing through the cam center P and parallel to the moving direction of the linear driven follower 4, and a line segment passing through the center of the roller contactor 5 and parallel to the moving direction of the sliding node 4. The interval (called offset) is set to zero, and the maximum value of the pressure angle is made as small as possible. However, even with such a design of zero offset, a pressure angle is naturally generated corresponding to the desired cam movement characteristic, and the pressure angle cannot be further reduced.

The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to make the maximum value of the pressure angle smaller than that of the conventional cam device while satisfying a predetermined motion characteristic. To do.

[0006]

Therefore, in the present invention, 1
Two radial cams A and B are attached to one rotary shaft, two contactors a and b are attached to one linearly driven follower, and the contactor a is brought into contact with the cam A, and the contactor b.
Is brought into contact with the cam B. The relationship between the cam A and the contact element a and the relationship between the cam B and the contact element b are the same phase and the same displacement given to the linear driven follower according to the rotation of the rotary shaft. Further, a line segment passing through the contact point of the cam A and the contactor a and parallel to the movement direction of the follower node and a line segment passing through the contact point of the cam B and the contactor b and parallel to the movement direction of the follower node are A line segment passing through the center of the rotation axis and parallel to the movement direction of the follower is sandwiched so as to have a symmetrical arrangement relationship.

[0007]

The relationship between the cam A and the contact a has an appropriate offset, not the above-mentioned offset zero. If the offset is positive, the relationship between the cam B and the contact b has a negative offset. Therefore, the pressure angle change characteristic caused by the relationship between the cam A and the contact a is different from the pressure angle change characteristic caused by the relationship between the cam B and the contact b. Therefore, the twisting force acting on the linear driven follower from the contact a (component force due to the pressure angle acting in the direction of swinging the follower) and the twisting force acting on the driven follower from the contact b respectively change. Since there is inevitably mechanical backlash, the linear driven follower oscillates slightly by the prying force. When the linearly driven follower swings, either one of the contacts a and b is microscopically separated from the cam A or B, and the additional load is almost borne by the one contact. It is the combination of the two sets of cams and contacts that has the smaller pressure angle that bears the additional load.

[0008]

2 and 3 show the schematic construction of a cam device according to an embodiment of the present invention. As shown in both figures, two radial cams 2a and 2b are attached to one rotary shaft 1, and both cams rotate integrally in the X direction around P. The linearly driven follower 4 is restricted by the guide 3 and moves linearly in the direction Y orthogonal to the rotary shaft 1. Two roller contactors 5a and 5b are attached to the lower end portion of the linear motion follower 4, and the roller contactor 5a contacts the cam 2a and the roller contactor 5b contacts the cam 2b.

As shown in FIG. 2, the roller contact 5 is attached to the follower 4 in a state of being offset by d1 with respect to the center of the cam. Similarly, the roller contact 5b is attached to the follower 4 in a state of being offset from the cam center P by -d1 in the opposite direction to the roller contact 5a.
In addition, the movement characteristics of the driven joint 4 due to the relationship between the cam 2a and the roller contactor 5a and the movement characteristics of the driven joint 4 due to the relationship between the cam 2b and the roller contactor 5b are in phase and identical. A cam profile is formed.

Further, as shown in FIG. 2, the pressure angle generated due to the relationship between the cam 2a and the roller contact 5a is θ1, and the cam 2
The pressure angle generated by the relationship between b and the roller contact 5b is θ2.

FIG. 4 shows the pressure angle θ associated with the rotation of the rotary shaft 1.
The change characteristics of 1 and θ2 are shown. Since the roller contacts 5a and 5b are offset in the opposite directions, the change characteristics of the pressure angles θ1 and θ2 are different as shown in the figure. The characteristic indicated by the dotted line in FIG. 4 is the change characteristic of the pressure angle θ of the same cam motion characteristic created by one cam and roller contactor (configuration in FIG. 1) with zero offset. With respect to the change characteristics of the pressure angle θ when the offset is zero, the maximum values of the pressure angles θ1 and θ2 when the offset is large to some extent are larger.

Assuming that the two roller contacts 5a and 5b are evenly loaded, the respective pressure angles θ1
And θ2 generate a force that twists the linear follower 4 in the direction Z orthogonal to the direction Y of movement. Unless the twisting force acting on the roller contactor 5a and the twisting force acting on the roller contactor 5b are opposite and equal in magnitude, the non-zero resultant force of the roller contacts 5a and 5b acts on the follower 4. In accordance with the resultant force, the follower 4 is microscopically oscillated and displaced in the direction of the twisting force.

When the linear driven follower 4 is displaced to one side in the direction of the arrow Z by the prying force, one of the two roller contacts 5a and 5b is microscopically separated from the cam 2a or 2b, The separated roller contactor does not bear any load, and one roller contactor that is still in contact with the cam bears almost the entire load.

In this way, in the process of displacing the follower 4 by actuating the portions of the cams 2a and 2b other than the basic circle, either the set of the cam 2a and the roller contactor 5a or the cam 2b and the roller contactor. The load is borne by either one of the pair with 5b. The group that bears the load is the group that produces the pressure angle when the absolute value of the pressure angle change characteristics θ1 and θ2 shown in FIG. 4 is smaller. Therefore, as shown by the thick solid line in FIG. 4, the load is borne by the set of roller contactors 5a exhibiting the characteristic of the pressure angle θ1 up to the middle, and θ1 and θ2
The total load is borne by the roller contactor 5b which produces the pressure angle θ2 from the time when the magnitude relationship of the absolute values of 1 and 2 is reversed. That is, the pressure angle in the actual operation characteristic of the cam device according to the embodiment of the present invention shown in FIGS. 2 and 3 changes as shown by the thick solid line in FIG. 4, and the conventional cam device having the same cam movement characteristic (see FIG. 1). (Apparatus), the peak value of the apparatus of the present invention is smaller by ΔS.

[0015]

As described above in detail, according to the present invention, the cam device composed of the combination of the radial cam and the linear driven follower does not become so complicated, and the same cam motion characteristic is satisfied while the pressure is satisfied. The maximum value of the angle can be made smaller than that of the conventional cam device. Therefore, the movement of the cam device becomes smoother, and the torque of the cam shaft drive source can be made smaller, which is an advantage.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a conventional cam device.

FIG. 2 is a front view of a cam device according to an embodiment of the present invention.

FIG. 3 is a side view of the apparatus according to the above embodiment.

FIG. 4 is a graph showing pressure angle change characteristics showing the action and effect of the device of the above embodiment.

[Explanation of symbols]

 1 rotary shaft 2, 2a, 2b radial cam 3 guide 4 linear driven follower 5, 5a, 5b roller contactor

Claims (1)

[Claims] 1. A cam device having the following configuration. Two radial cams A and B are attached to one rotating shaft, and two contactors a and b are attached to one linear driven follower. The contactor a contacts the cam A, and the contactor b contacts the cam B. Abut. The relationship between the cam A and the contact a and the relationship between the cam B and the contact b give the driven node the same phase and the same displacement as the rotary shaft rotates. The line segment passing through the contact point between the cam A and the contact a and parallel to the movement direction of the follower node, and the line segment passing through the contact point between the cam B and the contact b and parallel to the movement direction of the follower node are the rotary shafts. And a line segment passing through the center of the driven node and parallel to the movement direction of the follower node has a symmetrical arrangement relationship.