JPH0481652B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cam device comprising a cam and a follower driven by the cam.

[Conventional technology]

Conventionally, a so-called front cam as shown in FIG. 4 has been used as a cam device for accurately tracing a follower along a cam and pitch curve. That is, a cam 3 having a cam groove 2 of a constant width formed on its flat front surface is used along a pitch curve 1 in which the distance from the center of rotation changes, and a follower 6 is fitted into this cam groove 2 so as to be freely movable. It is something.

In this cam device, since the follower 6 is fitted into the cam groove 2, the follower 6 does not deviate greatly from the contour curve of the cam that forms the cam groove 2, so it can be used as a flat cam or an end cam that does not have a cam groove 2. By comparison, accurately trace the pitch curve 1 located in the center.

[Problem that the invention seeks to solve]

However, in this conventional cam device, since both the inner and outer contour curves forming the cam groove 2 rotate in the same direction, when the follower 6 touches the inner contour curve of the cam groove 2, Rotational forces are applied in opposite directions when touching the contour curve. Therefore, between the cam groove 2 and the follower 6,
Unless a certain amount of allowance is given, the follower 6 will not run smoothly while rotating.

However, if a margin is provided between the cam groove 2 and the follower 6, each time the direction of movement of the follower 6 changes, as shown in FIG. Do not accurately trace the pitch curve 1.

In addition, the follower 6 is rotated in opposite directions each time it touches the outer contour curve and the inner contour curve of the cam groove 2, so when the cam 3 rotates at high speed, the follower 6 is severely worn out.

This invention aims to solve the above-mentioned problems in conventional cam devices.

[Means to solve the problem]

Citing the symbols shown in Figures 1 and 3,
To explain the structure of the present invention, the cam device according to the present invention has a cam mechanism consisting of a cam and a follower that follows the contour curve, and the cam mechanism rotates around the same rotation center O at a constant angular velocity in mutually opposite directions. Comprising an outer cam 13 and an inner cam 14,
In a two-dimensional polar coordinate system having the rotation center O as the origin, when the contour curve forming the cam groove of the outer cam 13 is expressed by the formula R=f(θ), the inner cam 1
The contour curve forming the cam groove 12 of No. 3 is r=f(-
θ)-d, and the minimum value Rmin of the R coordinate of the contour curve of the outer cam 13 is greater than or equal to the maximum value rmax of the r coordinate of the contour curve of the cam groove 12 of the inner cam 13, and these outer cams 13 and the inner cam 14 are both aligned at the position where θ=0 in the two-dimensional polar coordinate system, and at this position the outer cam 13
This is characterized in that a follower 16 having a diameter equal to or less than the above d is fitted between the inner cam 14 and the inner cam 14.

[Effect]

The outer cam 13 and the inner cam 14 meet the difference between the R coordinate and the r coordinate of their contour curves, that is, the center of rotation O The distance R-r in the radial direction is d. The position where θ=0 is
For example, as shown in FIG. 1, if the hour hand is aligned perpendicularly to the 0 o'clock direction and the outer cam 13 and the inner cam 14 are rotated at a constant angular velocity ω in opposite directions around the rotation center O using this as a starting point, then Distances R and r of the contour curves of the outer cam 13 and the inner cam 14 from the rotation center O at the starting point position, that is, the 0 o'clock position of the hour hand
are R=f(ωt), r= with respect to time t, respectively.
It is expressed by the formula f(ωt)−d. That is, the distances R and r of the contour curve here change as time t passes, but the interval between them is R-r=d (constant).

Therefore, by fitting the follower 16 having a diameter of d or less between the outer cam 13 and the inner cam 14 at a position directly above the rotation center O, this follower 16 can be attached to the cams 13, 14. Move up and down to trace the middle.

At this time, even when the follower 16 contacts the outer cam 13 and the inner cam 14 at the same time, the outer cam 13 and the inner cam 14, which contact the follower 16 from above and below, are rotating in opposite directions, so the follower 16 remains constant. It is rotated in the direction of , and almost completely rolls into contact with the contour curve, with almost no sliding. Therefore, even if the diameter of the follower 16 is brought as close as possible to the distance d at the point where R-r=d, and there is almost no margin between the cam groove 12 and the follower 16, the follower 16 can easily connect to the outer cam 13. It moves smoothly between the inner cam 14.

Furthermore, the minimum value Rmin of the distance R from the rotation center O of the contour curve of the outer cam 13 to be formed is the maximum value of the distance r from the rotation center of the contour curve of the inner cam 14.
rmax or more, the outer cam 13 and the inner cam 14 do not interfere with each other during rotation.

〔Example〕

Next, an embodiment of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 shows the front shapes of the outer cam 13 and the inner cam 14, and the outer cam 13 and the inner cam 14 are rotatably supported around the same rotation center O.

As already mentioned, in the two-dimensional polar coordinate system with the rotation center O as the origin, when the contour curve forming the cam groove of the outer cam 13 is expressed by the formula R=f(θ), the cam of the inner cam 13 The contour curve forming the groove 12 is expressed by the formula r=f(-θ)-d. In addition, the minimum value of the R coordinate of the contour curve of the outer cam 13
Rmin is greater than or equal to the maximum value rmax of the r coordinate of the contour curve of the cam groove 12 of the inner cam 13.

The positions where the θ coordinate of the two-dimensional polar coordinates of the outer cam 13 and the inner cam 14 are 0 are aligned with each other, and the follower 16 of the driven joint 15 is fitted between the positions of both cams 13 and 14 where θ=0. . The follower 16 is preferably of a rotatable roller type, and its diameter is preferably as close to the above d as possible. however,
In practice, it is common to allow some margin for fitting in consideration of thermal expansion, errors, etc. of the corner components. In addition, in FIG. 1, 15 is a driven link connected to the follower 16.

In this state, the outer cam 13 and the inner cam 14 are rotated at equal angular speeds in opposite directions. FIG. 2 shows an example of the movement curve of the follower 16 in this case, where the direction of movement of the follower 16 changes by providing almost no margin between the cam groove 12 and the follower 16. Almost no movement of the follower 16 occurs.

Next, FIG. 3 shows a rotation transmission mechanism using a gear train as an example of a mechanism for rotating the outer cam 13 and the inner cam 14. That is, drive shaft 1
9 is transmitted in the opposite direction to the inner cam 14 via the planetary gear mechanism 20, and the rotation of the gear trains 21 and 2
2 and gear trains 23 and 24, the rotation of the drive shaft 19 is transmitted to the outer cam 13 in the forward direction. In this case, it goes without saying that the gear ratio of the square gear train is selected so that the rotation of the drive shaft 19 is transmitted to the inner cam 14 and the outer cam 13 at the same ratio.

In addition to such a gear train, the transmission mechanism from the drive shaft 19 to the outer cam 13 and inner cam 14 may include a sprocket and sprocket foil, a winding electric mechanism using a belt and a pulley, or a combination of these. etc. are available.

〔Effect of the invention〕

As explained above, according to the present invention, smooth operation of the follower 16 can be ensured without having to provide a large margin between the cam groove 12 and the follower 16, so that the follower 16 can be moved between the cams 13 and 14. In addition, while the follower 16 rotates in a fixed direction, it almost completely rolls into contact with both the outer cam 13 and the inner cam 14. Therefore, wear of the contact portions of the follower 16, the outer cam 13, and the inner cam 14 can be minimized.

[Brief explanation of the drawing]

FIG. 1 is a contour view of a cam showing an embodiment of the present invention, FIG. 2 is a graph showing an operating curve of the follower 16 in the same embodiment, and FIG. 3 is a cam driving force transmission mechanism in the same embodiment. FIG. 4 is a gear meshing diagram showing an example, and FIG. 5 is a contour diagram showing a conventional example of a cam.
The figure is a graph showing an operating curve of the follower 16 of the same cam. 13...outer cam, 14...inner cam, 16...
…Fuoroa.

Claims (1)

[Claims] 1. A cam mechanism consisting of a cam and a follower that follows this contour curve, comprising an outer cam 13 and an inner cam 14 that rotate in opposite directions at a constant angular velocity around the same rotation center O, In a two-dimensional polar coordinate system with O as the origin, the contour curve forming the cam groove of the outer cam 13 is R=f
(θ), the contour curve forming the cam groove 12 of the inner cam 13 is expressed by the formula r=f(-θ)-d, and the R coordinate of the contour curve of the outer cam 13 is The minimum value Rmin is the cam groove 12 of the inner cam 13.
is greater than or equal to the maximum value rmax of the r coordinate of the contour curve,
Both the outer cam 13 and the inner cam 14 are aligned at the position θ=0 in the two-dimensional polar coordinate system, and at this position there is a diameter of less than the above d between the outer cam 13 and the inner cam 14. Holds follower 16
A cam device characterized by being fitted with.