JPH08141506A - Cam unit - Google Patents

Abstract

PURPOSE: To decrease the coefficient of friction of the contact point of a cam with a follower by constituting, in a cam unit used as a constitutional element of a mechanical apparatus, the cam, and the follower, or at least either one of them of an ultrasonic oscillation generating means. CONSTITUTION: In a cam unit wherein a channel cam 10 is used, a high frequency electric signal generated by an oscillator 9 is applied on an ultrasonic oscillator 1 and it is converted into a mechanical oscillation in the ultrasonic range by means of the oscillator 1. The oscillation generated by means of the ultrasonic oscillator 1 is expanded by means of a horn 2 for expansion of amplitude fixed on a sleeve 7 at a flange 6 part provided on a node point of the oscillation and is transmitted to a follower 3 fixed on the apex of the horn 2. By providing the ultrasonic oscillation to the follower 3 like this, the frictional characteristics of the contact point of the cam 10 with the follower 3 is decreased and the driving force of the cam can be accordingly decreased. In addition, heat generation, wear and stick-slip can be prevented from occurring.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cam unit used as a component of a mechanical device.

[0002]

2. Description of the Related Art In a mechanical device, a cam unit is used as a mechanism for converting a rotary motion into a linear motion, a rotary motion into a swing motion, and a motion direction of a linear motion. The cam unit consisting of a rotating plate cam and a linear motion follower (Fig. 3) is most often used, and the rotary motion of the plate cam can be converted into a linear motion by a follower contacting the side surface of the cylinder. The motion of the follower is determined by the circumferential shape of the plate cam and the number of rotations.

A cam unit (FIG. 4) using a linear cam is used to convert the linear motion into different forms of linear motion. In this case, as the cam reciprocates left and right on the guide, the follower in contact with the cam follows the shape of the upper surface of the cam and moves in the vertical direction of the paper surface. In addition to the above-described cam unit, there are a unit in which a plate cam is combined with a swinging follower, and a unit in which a groove cam in which a follower moves along a groove formed on an end surface or a cylindrical surface of the cam is used. In particular, grooved cams are often used in automatic assembly machines and automatic processing machines. As special ones, there are cam units such as Geneva, parallel, barrel and roller gear. Furthermore, various methods are known for using a cam in combination with a gear or a link to obtain a special motion.

A roller as shown in FIG. 3 is usually provided at the tip of the follower at the portion where the cam and the follower come into contact with each other. This roller follows the movement of the cam by rotation. This has the function of smoothing the contact between the cam and the follower. However, in an automatic machine, in order to reduce the pressure angle and the allocation angle at the tip of the follower, the contact surface with the cam of the follower is often the edge of the minimum R instead of the roller.

[0005]

When the cam and the follower move in contact with each other, it is a general method to provide a roller at the tip of the follower and make contact with the cam via the roller. However, as mentioned above, for applications that require more complicated and delicate movements, the pressure angle and allocation angle of the follower tip should be reduced and the contact surface with the cam of the follower should be
The edge of the minimum R may be used instead of the roller. In the cam unit having such a structure, the cam and the follower are in sliding contact with each other, and sliding friction occurs between the cam and the follower. Therefore, there is a problem that it affects the transmission efficiency between the cam and the follower.

Further, there are problems that heat is generated due to friction between the contact points of the cam and the follower, wear is likely to occur, and lubrication with a lubricant is indispensable. further,
There is also a problem that stick-slip easily occurs due to friction. The object of the present invention is to solve these problems.

[0007]

[Means for Solving the Problems] In order to solve the above-mentioned problems, as a result of intensive research, as a result, “an ultrasonic wave composed of a cam, a follower, and an ultrasonic vibrating means for ultrasonically vibrating at least one of the cam and the follower It has been found that the above-mentioned problems can be solved by using a "vibrating cam unit" or "a cam unit according to claim 1, characterized in that the follower has a structure in which an ultrasonic wave generating means is incorporated therein". Invented the invention.

[0008]

It is known that the frictional force between solids is reduced by applying ultrasonic vibration to the sliding surfaces of the solids that are in contact with each other. That is, the cam used in the cam unit,
Alternatively, by applying ultrasonic vibration to the follower, the friction coefficient at the contact point between the cam and the follower decreases.
Now, considering a rotating plate cam and a cam unit having a structure in which a follower comes into contact with the cylindrical side surface thereof, the power for driving the plate cam can be expressed by equation (1).

W = μfrω (1) where W: power, f: force of follower pushing cam,
r: average radius from the camshaft rotation center, μ: friction coefficient,
ω: The angular velocity of the cam. As shown in the equation (1), the power W is found to be proportional to the friction coefficient μ between the cam and the follower. On the other hand, as described above, it is known that the friction coefficient μ decreases by applying ultrasonic vibration to the sliding surface.Therefore, by applying ultrasonic vibration to the cam or follower, The frictional force (μ × f) generated at the contact point between the follower and the follower is reduced. Therefore, from the formula (1), the power W for driving the cam decreases. This phenomenon is not limited to plate cams,
The same can be said for the groove cam and the like.

Hereinafter, the present invention will be described in more detail by way of examples with reference to the drawings, but the present invention is not limited thereto.

[0011]

FIG. 1 shows an embodiment in which a follower 3 is subjected to ultrasonic vibration in a cam unit using a grooved cam 10. The high frequency electric signal generated by the oscillator 9 is applied to the ultrasonic transducer 1. The applied electric signal is converted into mechanical vibration in the ultrasonic range by the ultrasonic vibrator 1. The amplitude of the vibration generated by the ultrasonic transducer 1 is expanded by the amplitude expanding horn 2 mounted to further enhance the effect of the ultrasonic wave, and is transmitted to the follower 3 mounted at the tip of the amplitude expanding horn 2. Transmitted. The amplitude amplifying horn 2 is fixed to the sleeve 7 at a flange 6 portion provided at a vibration node (node point).

The ultrasonic oscillator 1, the amplitude amplifying horn 2, and the follower 3 attached to the tip of the ultrasonic oscillator 1 have a resonance state at a vibration frequency substantially the same as the resonance frequency when the ultrasonic vibrator 1 is driven alone. Is designed to be The rod 15 mounted at a diagonal position on the cylindrical side surface of the sleeve 7 for fixing the ultrasonic vibration system can be slidably moved in the lateral direction of the paper surface of FIG. By rotating and driving the groove cam 10 having a groove formed on the cylindrical side surface attached to the rotary shaft 5, the ultrasonic transducer 1, the amplitude expanding horn 2, the follower 3, which meshes with the groove of the groove cam 10,
The member composed of the flange 6 and the sleeve 7 is the groove cam 1
It operates according to the groove shape of 0.

In the embodiment of the grooved cam shown in FIG. 1, the vibration frequency of ultrasonic vibration is about 28.5 kHz, the input power from the oscillator 9 to the ultrasonic vibrator 1 is about 27 W, and the vibration of the side surface near the tip of the follower 3 is small. The amplitude is about 20 μm. The oscillator has an automatic frequency tracking function in order to cope with changes in the resonance frequency due to temperature rise of the vibration system and load changes. In the embodiment of the groove cam shown in FIG. 1, the follower 3 was subjected to ultrasonic vibration in the twisting direction. As can be seen from the equation (1), the power for driving the grooved cam 10 was almost 2/3. By reducing the friction coefficient at the contact point between the cam and the follower, the driving power of the cam could be significantly reduced. It was also effective in preventing heat generation, wear, and stick slip.

FIG. 2 shows an embodiment in the case where ultrasonic vibration is applied to the follower in a cam unit using a plate cam. The configuration of the ultrasonic vibration system is the same as that of the cam unit using the grooved cam shown in FIG. Follower 3
Contacts the cylindrical side surface of the plate cam 4 attached to the rotary shaft 5. As the plate cam 4 rotates, the ultrasonic transducer 1, the amplitude-enhancing horn 2, the follower 3, the flange 6, and the sleeve 7 follow the shape of the cylindrical side surface of the plate cam 4.
The member configured by moves in the vertical direction of the paper surface of FIG. 1 along the slide guide 8.

Also in the embodiment of the plate cam shown in FIG. 2, ultrasonic vibration in the twisting direction was applied to the follower 3 as in the case of the groove cam. The power for driving the plate cam 4 was almost 2/3. By reducing the friction coefficient at the contact point between the cam and the follower, the driving power of the cam could be significantly reduced. It was also effective in preventing heat generation, wear, and stick slip.

The present invention is not limited to the above-mentioned application to the cam unit, but can be applied to Geneva, parallel, barrel, roller gear and the like. Further, although the torsional vibration is used in the present embodiment, the present invention is not limited to this, and it is also possible to use flexural vibration, longitudinal vibration and the like.

[0017]

In the cam unit according to the present invention,
By reducing the friction coefficient at the contact point between the cam and the follower, the driving power of the cam can be significantly reduced. Further, since the frictional force is reduced, heat generation is reduced and the amount of wear at the contact points is reduced. It also has the effect of preventing stick-slip. Further, since the frictional force can be reduced without supplying the lubricant, the effect can be expected even in applications where the lubricant cannot be used.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a cam unit using a groove cam in which ultrasonic vibration is applied to a follower according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of a cam unit using a plate cam in which ultrasonic vibration is applied to a follower according to an embodiment of the present invention.

FIG. 3 is a schematic diagram of a cam unit using a plate cam according to a conventional technique.

FIG. 4 is a diagram of a cam unit using a linear cam according to the related art.

[Explanation of symbols]

 1 ・ ・ ・ Ultrasonic transducer 2 ・ ・ ・ Amplitude amplification horn 3 ・ ・ ・ Follower 4 ・ ・ ・ Plate cam 5 ・ ・ ・ Rotating shaft 6 ・ ・ ・ Flange 7 ・ ・ ・ Sleeve 8 ・ ・ ・ Sliding guide 9 ・ ・ ・ Oscillator 10 ・ ・ ・ Groove cam 11 ・ ・ ・ Vibration mode 12 ・ ・ ・ Linear cam 13 ・ ・ ・ Linear guide 14 ・ ・ ・ Bearing 15 ・ ・ ・ Rod 16 ・ ・ ・ Roller 17 ・ ・ ・ Key or more

Claims (2)

[Claims] 1. A cam unit comprising a cam, a follower, and an ultrasonic vibration generating means for ultrasonically vibrating at least one of the cam and the follower. 2. The cam unit according to claim 1, wherein the follower has a structure in which ultrasonic wave generating means is incorporated.