JP2008045662A - Cam unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To acquire an intermediate estimation of respective estimated elements in comparison with a roller cam mechanism and a barrel cam mechanism, which have both merits and demerits, and to provide a cam mechanism flexibly responding to a permissible storage space. <P>SOLUTION: A truncated cone 6 in which the rotary shaft (output shaft) 5 of a turret 4 becomes an axis is arranged on the turret 4, a cam follower 3 is arranged on the slanted surface of the truncated cone 6, an input shaft 2 direction of an input cam 1 is orthogonal to an output shaft direction of the turret 4, and a cam groove 7 or rib 9 of the input cam 1 is fitted in the cam follower 3. Thus, preload can be also applied on the cam mechanisms, so that a pressure angle at the time of a stoppage and the maximum pressure angle become intermediate between those of a roller gear cam and barrel cam, a dimensional ratio between a Y-direction and Z-direction is changed by changing the angle of the slanted surface, and the cam mechanisms is easily adjusted for the permissible storage space. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention belongs to the technical field of a three-dimensional cam mechanism among cam mechanisms used as an index mechanism.

Conventionally, among general index mechanisms, a three-dimensional cam mechanism includes a roller gear cam mechanism and a barrel cam mechanism.
FIG. 2A is a schematic side view of a conventional roller gear cam mechanism. A rotational driving force from a motor is applied to the input shaft 2 of the input cam 1 directly or via a driving mechanism. This rotation is a one-way continuous rotation.
The input cam 1 has a predetermined thickness dimension in the input shaft direction, and a cam groove 7 having a twist in the axial direction within the range of the thickness dimension along the circumference is provided on the circumferential surface thereof. The cam follower 3 provided in the turret 4 is fitted in the cam groove 7. The cam follower 3 is a straight roller in the case of FIG. 2, but may be a tapered roller or a ball. When the input cam 1 rotates in this fitted state, the cam follower 3 moves according to the twist of the cam groove 7, so that the turret 4 also rotates the sector around the output shaft 5 or intermittently in one direction. .

FIG. 2B is a schematic side view of the barrel cam mechanism.
In the case of the barrel cam mechanism, the cam follower 3 is provided on the lower surface of the turret 4 that rotates about the output shaft 5, and the cam follower 3 is a cam groove 7 of the input cam 1 whose axial direction is orthogonal to the output shaft direction. It is designed to fit in.
As in the case of the roller gear cam mechanism (a), the input cam 1 has a predetermined thickness dimension in the input shaft direction, and the cam grooves 7 and the like are twisted in the axial direction along the circumferential surface thereof. Since the force is applied to the cam follower 3 from the side wall of the cam groove 7 by the rotation of the input cam 1, the turret 4 rotates the sector around the output shaft 5 or intermittently in one direction. Become.

FIG. 3A is a structural diagram of an example of a roller gear cam mechanism. This is a plan view corresponding to FIG. 2A viewed from above or from below.
FIG. 3B is a structural diagram of an example of the barrel cam mechanism. This is a perspective view corresponding to a case where (b) of FIG. 2 is looked down from the upper left.
With such a structure, when the input cam 1 is continuously rotated in one direction, the turret 4 rotates the sector around the output shaft 5 or intermittently rotates in one direction (for example, Non-Patent Document 1). 2).
Edited by Japan Cam Industry Association, “Cam Mechanism Handbook”, first edition, Nikkan Kogyo Shimbun, December 25, 2001, pp. 176-178 Makino Hiroshi, "Automatic Mechanical Mechanics", first edition, Nikkan Kogyo Shimbun, June 1, 1976, 290-304

However, the roller gear cam mechanism and the barrel cam mechanism described above are superior or inferior in some mechanism evaluation elements.
First, there are a stationary pressure angle and a maximum pressure angle as evaluation factors.
The pressure angle is defined as the direction of the pressing force when the cam surface is in contact with the cam follower surface and applying a pressing force to the cam follower, that is, the direction of the common normal at the contact point between the cam surface and the cam follower and the direction of the cam follower movement. It is a horn. Usually, it is represented by the symbol ψ. Therefore, the case where the pressure angle ψ is zero means that the direction of the pressing force and the direction of the movement of the cam follower coincide with each other. Therefore, the pressing force F from the cam is most effectively changed to 100% cam follower. Will work.

When the pressure angle ψ increases, the force f acting on the cam follower in the direction of motion of the pressing force F decreases as Fcos ψ, and no force is applied to the cam follower in the direction of ψ = 90 degrees.
Therefore, a smaller pressure angle is desirable in the cam mechanism.
With regard to such a pressure angle, the pressure angle during stopping means that the turret with the cam follower is in a stopped state (referred to as stopping) and a rotating state (this is referred to as positioning) with respect to continuous rotation of the input cam. The pressure angle in the stopped state. The maximum pressure angle is the largest pressure angle in the process in which the pressure angle changes from moment to moment in the rotating state of the turret.

  When the roller gear cam and the barrel cam are compared with each other, the pressure angle at the time of stopping is as follows. For the roller gear cam, the direction of the force F applied from the input cam 1 to the cam follower 3 and the direction of movement M of the cam follower 3 are as shown in FIG. Since it is the same, it is 0 degree. In the barrel cam, as shown in FIG. 4 (b), the direction of the force F applied from the input cam 1 to the cam follower 3 is different from the movement direction M of the cam follower 3. It has an angle ψ that is not 0 degrees.

At the maximum pressure angle, the roller gear cam is larger than the barrel cam.
The reason is as follows.
The roller gear cam mechanism and barrel cam mechanism, which have the same turret diameter, input cam diameter, number of cam followers, turret rotation / stopping mode, sector rotation angle, etc., have the same range of pressure angle change. is there.
On the other hand, in the roller gear cam mechanism, the pressure angle changes on one side with respect to the direction of movement of the cam follower, whereas in the barrel cam mechanism, the cam follower 3 is pushed in the same direction by the cam pressing surface as shown in FIG. Even if it is pushed by the pressure F, the cam follower 3 itself moves along the circumferential direction due to the rotation of the turret, so that the direction of the cam follower 3 is directed to the right of the force F at the lowest stage. However, the direction of the force F is in the middle stage, and the direction of the force F is directed to the left in the uppermost stage.

Thus, the direction of motion of the cam follower 3 is distributed to the right side and the left side of the direction of the force F.
Therefore, even if the change range of the pressure angle is the same, the maximum angle of the pressure angle is smaller than the maximum angle of the pressure angle when the pressure F changes only on one side by being distributed to the left and right.
For the above reasons, the roller gear cam mechanism in which the direction of the force F and the direction of the cam follower movement are not interchanged is larger than the maximum angle of the barrel cam mechanism in which the left and right are interchanged.

The next evaluation factor is ease of preloading.
This preload is the pressure at the contact portion between the cam and the cam follower that is applied in advance before the operation.
Applying preload makes it easier to absorb backlash between the cam and cam follower during operation, which is caused by machining errors of parts of related components such as cams, cam followers and turrets, and their assembly errors. As a stable thing.

In the roller gear cam, as shown in FIG. 3A, the contact surfaces of the input cam and the two cam followers are in a C-shaped contact, so that the distance between the output shaft of the turret and the input shaft of the input cam is finely adjusted. Thus, it is easy to adjust the contact pressure between the cam follower 3 and the inclined surface of the input cam 1.
On the other hand, in the barrel cam, as shown in FIG. 3B, the cam follower 3 is provided perpendicular to the turret 4, so that the roller surface of the cam follower 3 is also perpendicular, and the rib 9 in contact with this roller surface. The side of is also vertical. Therefore, even if the position of the turret 4 is changed in the vertical direction, no pressure can be applied between the cam follower 3 and the side surface of the rib 9. However, this is possible when the cam follower is a tapered roller.

  Next, as for the overall size, if the diameter of the input cam and the diameter of the turret are the same between (a) and (b) of FIG. 2, the dimension in the Z direction is the direction of the barrel cam mechanism of (b). And the dimension in the Y direction is larger in the roller gear cam mechanism (a).

  As described above, between the conventional roller gear cam mechanism and the barrel cam mechanism, there are advantages and disadvantages in the evaluation items such as the stationary pressure angle, the maximum pressure angle, whether or not the preload can be applied, the dimension in the Z direction, and the dimension in the Y direction. There is. That is, there is a problem that advantages and disadvantages alternate.

  An object of the present invention is to provide a three-dimensional cam type index device that can obtain an intermediate evaluation between a roller gear cam mechanism and a barrel cam mechanism in each evaluation item in view of the problems of the above-described conventional technology.

In order to solve the above-described problems, the present invention has the following configurations.
In the first configuration (basic configuration) of the present invention, a cam follower provided on a turret attached to an output shaft is fitted in a cam groove or a cam rib of an input cam, and the turret rotates in accordance with one-way continuous rotation of the input cam. The cam device is characterized in that the turret has a frustoconical portion whose axis is the rotation axis, and the cam follower is provided on an inclined surface of the frustoconical portion.

  A second configuration of the present invention is the cam device according to the first configuration, wherein the cam follower is a straight roller.

  A third configuration of the present invention is the cam device according to the first configuration, wherein the cam follower is a tapered roller.

  A fourth configuration of the present invention is the cam device according to the first configuration, wherein the cam follower is a ball.

  The structure of the cam mechanism of the present invention, as described in the above-mentioned problem solving means, has a truncated cone part with its rotating shaft as an axis in the turret, and a cam follower is erected on the inclined surface of the truncated cone part, Since the cam follower is structured to rotate with the input cam fitted thereto, a roller gear cam mechanism (FIG. 2 (a)) in which the cam follower is erected in the horizontal radial direction on the rotating peripheral surface of the turret, This has an intermediate characteristic of a barrel cam mechanism (FIG. 2B) in which a cam follower is erected on the lower surface in the same direction as the output shaft.

As a result, the pressure angle at the time of stopping does not become 0 degrees as in the roller gear cam, but becomes smaller than the barrel cam of the same scale. The maximum pressure angle is smaller than the roller gear cam but larger than the barrel cam.
Preload adjustment is possible with a roller gear cam, and preload is not applied with a barrel cam. Since the side surface is also inclined accordingly, the preload can be applied by adjusting the position of the input shaft of the input cam so as to approach or move away from the inclined surface of the turret.

  As for the overall dimensions, since the input cam is located at an intermediate position between (a) and (b) in FIG. 2, that is, diagonally to the left of the turret 4, the dimension in the Y direction is smaller than that of the roller gear cam, and the dimension in the Z direction. Is smaller than the barrel cam. Whether the dimension in the Y direction or the Z direction is made smaller can be selected by selecting the tilt angle of the turret truncated cone.

  The feature of the present invention is that the turret has an inclined surface of a truncated cone, a cam follower is erected on the inclined surface, an input cam is provided at an oblique position between the roller gear cam and the barrel cam, and the overall dimensional shape is made compact. In this case, it is best that the position of the input cam is provided in a direction of 45 degrees from the rotation center position of the turret with respect to the turret rotation surface.

Embodiments of the cam device of the present invention will be described below with reference to the drawings.
FIG. 1 is a side view comparing the cam device of the present invention with a conventional roller gear cam mechanism and barrel cam mechanism. (A) is a roller gear cam mechanism, (b) is an embodiment of the cam device of the present invention, and (c) is a barrel cam mechanism.
In the cam device of the present invention, a truncated cone portion 6 is provided on the lower surface side of the turret 4, and a predetermined number (for example, six) of cam followers 3 are erected at regular intervals perpendicularly to the inclined surface (in the figure, left and right sides). Only two are shown and others are omitted).
β is an angle between the normal of the inclined surface of the truncated cone portion 6 and the rotational surface of the turret 4.
Thus, the cam device of the present invention has an intermediate structure between the roller gear cam mechanism and the barrel cam mechanism with respect to the angle at which the cam follower 3 is erected.

That is, the roller gear cam mechanism is when β = 0 degrees, and the barrel cam mechanism is when β = 90 degrees.
Because of such an intermediate structure, the evaluation element also has an intermediate characteristic between the roller gear cam mechanism and the barrel cam mechanism as described in the column of the effect of the invention. The stationary pressure angle is not 0 degrees as in the roller gear cam mechanism, but is smaller than the barrel cam mechanism. The maximum pressure angle is larger in the roller gear cam mechanism and smaller in the barrel cam mechanism, but in the cam apparatus of the present invention, the maximum pressure angle is an intermediate size.

The preload between the cam and the cam follower is easily applied by the roller gear cam mechanism and difficult by the barrel cam mechanism, but can be applied in accordance with the roller gear cam mechanism in the cam apparatus of the present invention.
The outer dimensions can also be smaller than the roller gear cam mechanism in the Y direction and smaller than the barrel cam mechanism in the Z direction.
Therefore, the possibility of accommodation is expanded by selecting the angle β according to the shape and size of the installation allowable space.

  In the above example, the cam follower is a straight roller, but the cam follower is not limited to this, and may be a tapered roller or a ball.

It is the figure which showed the structure of the Example of this invention, and the structure of the roller gear cam mechanism and barrel cam mechanism for a comparison. It is a basic structure schematic diagram of a roller gear cam mechanism and a barrel cam mechanism. It is an external appearance structural diagram of an example of a roller gear cam mechanism and a barrel cam mechanism. It is explanatory drawing of the pressure angle in a roller gear cam mechanism and a barrel cam mechanism.

Explanation of symbols

1 Input Cam 2 Input Shaft 3 Cam Follower 4 Turret 5 Output Shaft 6 Frustum Portion 7 Cam Groove 8 Turret 9 Rib

Claims (4)

  A cam device in which a cam follower provided on a turret attached to an output shaft is fitted in a cam groove or a cam rib of an input cam, and the turret rotates in accordance with one-way continuous rotation of the input cam. A cam device comprising a truncated cone part having an axis as an axis, wherein the cam follower is provided on an inclined surface of the truncated cone part.   The cam device according to claim 1, wherein the cam follower is a straight roller.   The cam device according to claim 1, wherein the cam follower is a tapered roller. The cam device according to claim 1, wherein the cam follower is a ball.

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