SU739295A1 - Cam and roller gear for converting continuous rotary motion into intermittent rotary motion - Google Patents

Description

(54) CAM-ROLLER MECHANISM FOR TRANSFORMING CONTINUOUS ROTATION IN INTERRUPTED

one

The invention relates to general engineering, in particular, mechanisms for converting continuous rotation to intermittent, and can be used, for example, in drives of the roller feed systems of high-speed automatic presses for carrying out precision feed of the tape to one shaft.

A known mechanism for converting continuous rotation into discontinuous, containing a leading worm with a variable pitch and a driven drum with rollers 1.

The disadvantage of this mechanism is the difficulty of manufacturing a precision screw with variable pitch with high accuracy.

The closest to the technical essence of the invention is a cam-roller mechanism for converting continuous rotation into an intermittent, containing a driving cam made in the form of a disk with a curved profile protrusion located at its end consisting of a spiral section and a section with a constant radius of curvature, and driven drum with rollers radially mounted on it 2.

The design of the drive link of this mechanism is much simpler to manufacture than the worm with a variable pitch, but onex has the disadvantage that the cam cannot be covered by a pair of adjacent rollers of the driven drum. This is prevented by a rectangular cam lobe section. The resulting play between the elements of the driving and driven members and the point contact of the roller with the cam leads to inaccuracy of supply and reduces to the starting load of the mechanism. As a result

10 t indicated cam-roller mechanism can not be used in high-speed drives.

The aim of the invention is to increase the speed and load capacity.

15 mechanism.

This goal is achieved by the fact that the spiral section of the cam profile is made with a variable clamp, the section with a constant radius of curvature is made in the form of two 20 arcs of circles, which are conjugated to the beginning and the end of the spiral section and located in the general sector of the disk are equidistant to each other, the cross section of the cam has the shape of a circle, and each roller et

home drum is a globoid shape, in which the curvature of the concave surface corresponds to the curvature of the cross section of the hatch.

In addition, in order to ensure unhindered entry of the roller into engagement with the cam and release from the engagement, the ends of the circular arcs adjacent to the helical section are located outside the general sector of the disc by a value of 0.5-0.8 of the diameter of the rollers.

FIG. 1 shows the proposed mechanism, a vertical section; in fig. 2 is a schematic illustration of a cam.

The cam-roller mechanism for converting continuous rotation into discontinuous contains a driving cam, which is a disk 1 with a protrusion 2 made at its end with a curvilinear profile consisting of a spiral section of a LED with a variable pitch of a spiral (Fig. 2) and two arcs of circles DEP and ABC, located coaxially with the disk 1 in the total spectrum of the disk, indicated in FIG. 2 angle. The cross section of the cam part is a circle 3. The driven element of the mechanism is the drum 4 with axles 5 mounted on its surface with the possibility of rotation around these axes and moving along them rollers 6 interacting with curved protrusion 2 cam. Each roller has the shape of a globoid, whose curvature of the concave surface corresponds to the curvature of the cam cross section.

For unhindered entry of the rollers into engagement with the cam and disengagement of the engagement, the DE and BC portions of the circles DER and ABC, equal in length to 0.5. – 0.8 of the diameter of the rollers 6, are located outside the general sector of the disk 1.

The dimensions of the rollers and their placement on the drum 4 are selected in such a way as to ensure that the cam with the tension is covered by two adjacent rollers. This eliminates the backlash of the slave link.

Cam-roller mechanism works as follows.

With continuous rotation of the disk 1, the rollers roll in pairs around the cam. At each revolution of the drive disk 1, the driven shaft of the drum 4 is rotated at a predetermined angle o. and stops to stand, during which a process operation (e.g., stamping) occurs.

In this case, at the moment when one pair of rollers, for example, 6 and 7 (Fig. 1), moves from the spiral section to the arc of the circle DR, the other pair of rollers 7 and 8 at the same time engages with the other circle AB. Thus, when moving the rollers in the zone of arcs of circles EP

and AB three rollers 6, 7 and 8 are engaged with two arcs EP and AB. With

Further rotation of the drive disk external pair of rollers 6 and 7 descends from the arc EP, and the driven shaft with the drum continues to stand up, as the second pair of rollers 7 and 8 is in engagement with the portion of the arc BC. 5 Then the rollers 7 and 8 enter into the zone of the beginning of the SD spiral, and the driven shaft with the drum begins to move to a new angle a.

The ratio of the length of rotation and the distance of the driven member, as well as the magnitude of its angle of rotation, depend on the parameters of the spiral section of the DM, the length of the arc sections AC and DR of the driving cam. To ensure the reliable operation of the proposed mechanism, the following features of the cam design are provided.

The uninterrupted entry of the rollers into engagement with the arc section AB and their disengagement from the arc section EP is provided by segments DE and BC located outside the common sector.

As noted above, the engagement of the rollers with the cam profile is performed with tension. Therefore, in order to skip the roller 7, which passes between the sections AB and EP, the external side of the section AB, facing the section EP, is performed so as to provide a gap between it and the roller 7. At the same time, the necessary tension r to avoid backlash is provided by the rollers 6 and 7 running around the EF.

In addition, in order to avoid pinching

 rollers 6-8 at the time of their interaction with sections AB and EF of the cam, the plane of the protrusion 2 is located relative to the plane of the disk 1 at an angle y (Fig. 3), which depends on the radius R of the driven link, the angle

5 between the rollers (Fig. 1), as well as from the parameters of the SD spiral. This angle can be set by calculation.

Performing a helical section with a variable schagom helix ensures a smooth increase in the angular velocity of the driven

0 drum from up to the maximum speed and the same smooth slowdown to the next stand. The cam cross section in the form of a circle and rollers in the form of a globoid provides

linear contact of the cam with the rollers, which increases the load capacity of the mechanism.

Claims (2)

Invention Formula I. A cam-roller mechanism for converting a continuous rotation into an intermittent, containing a driving cam, made in the form of a disk with a curved profile protrusion located at its end, consisting of a spiral section and a section with a constant radius of curvature, and a driven drum with radially mounted on it rollers, different By the fact that, in order to increase the speed and load capacity of the mechanism, the spiral section of the cam profile is made with variable pitch, the section with a constant radius of curvature is made in the form of two arcs of circles that are conjugate to the beginning and end of the spiral section and are located in the general sector of the disk equidistantly each other, the cam cross section has the shape of a circle, and each roller of the driven drum has the shape of a globoid, in which the curvature of the concave surface corresponds to the curvature of the cross section of the cam. 2. The cam-roller mechanism according to claim 1, characterized in that, in order to ensure the roller unhindered in engagement with the cam and exit from the engagement, the ends of the circular arcs conjugate to the helical section are located outside the general sector of the disk by 0.5-0.8 diameter of the driven drum rollers. Sources of information taken into account in the examination 1. USSR author's certificate number 428136, cl. F 16 H 1/16, 1972. 2. Kolesnikov S.N. and others. Mechanisms., “Mechanical Engineering 1976, p. 475-476, fig. 7.92 (prototype)