JPH0719422Y2 - Cam selection device of zigzag sewing machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Field of the Invention The present invention relates to a cam selection device for a zigzag sewing machine.

2. Description of the Related Art There are several types of cam selection devices for zigzag sewing machines, one of which is a type that uses a spline shaft. The figure shows an example,
A spline shaft 4 whose both ends are rotatably supported by bearings 3 in parallel with a laminated cam 2 which is rotationally driven by a main shaft 1.
And a bracket 5 in which a guide shaft 6 is rotatably supported by the shaft 4 and extends horizontally between the arms 5a orthogonal to the shaft 4 and in parallel with the spline shaft 4. A cam follower 10 in which a screw pin 7 slidably supported and screwed into a base engages a spiral groove 8 of a spline shaft 4 and a guide shaft 6 is fitted in a groove 9 having a free end. When the spline shaft 4 is rotated by an external operation, the cam follower 10 stopped by the guide shaft 6 moves in the axial direction to select the cam 2 and is selected. The cam 2 allows the cam follower 10 and the bracket 5 to swing around the spline shaft 4. The movement of the pedestal 13 is achieved by engaging the pin 12 projecting laterally from the tip of the arm 5a with the pin 13 projecting from the pedestal 13 having an inverted L-shaped cross section from the upper side at a right angle. The pedestal 13 is oscillated around a support shaft 16 which is rotatably supported by a substrate 15 (see FIG. 3), and the pedestal 13 can be swung to adjust its position on the pedestal. It is transmitted to the bell crank 18 through the naive roller 17,
The swinging motion is transmitted to a needle bar (not shown) through the swinging plate 19.

In the type in which the cam is selected by rotating the spline shaft, a cam follower that is supported by the support shaft so as to be rotatable and slidable is moved in the axial direction of the support shaft via a link mechanism. Compared to the type, there is an advantage that the structure is simplified because it does not have a link mechanism, but in order for the cam follower 10 to select each cam 2 accurately, the rotation amount of the spline shaft 4 is set in advance. It must be placed and must be reliably positioned at the chosen location. Conventionally, therefore, a positioning cam 21 is fixed to the spline shaft 4 as shown in FIG. 7, and a leaf spring 23 attached to the machine frame 22 is attached to the cam 21.
The spline shaft 4 can be rotated by a fixed amount (90 ° in the figure) by elastically contacting.

The cam is selected after the cam follower 10 is once lifted from the cam. For this reason, the lever 24 is connected to the arm 5a on one side of the bracket 5, and is linked to the operation of selecting the cam.
The bracket 5 can be lifted by pushing up. Reference numeral 25 is a spring that urges the bracket 5 to rotate downward and presses the cam follower 10 against the cam 2.

Problems to be Solved by the Invention In the above-described conventional device, when the cam follower 10 follows the cam 2 and swings around the spline shaft 4, the spline shaft 4 is in a fixed state, and therefore the screw pin 7 is fixed. Reciprocate along the spiral groove 8. Therefore, due to the axial component of the spiral groove 8, the cam follower 10 slightly vibrates in the axial direction while performing the swinging motion, and follows the meandering on the cam surface as shown in FIG. When machining the cam surface, the machining accuracy is required over almost the entire width of the cam surface.

The present invention prevents the cam follower from moving slightly in the axial direction and limits the contact points of the cam follower, so that the machining accuracy of the cam surface is required within a narrow range. The purpose is to facilitate the production and reduce the production cost.

Therefore, the present invention is characterized in that a bracket is attached instead of attaching a spring for engaging the positioning cam and restraining the movement of the cam to the machine frame.

That is, the present invention is directed to a spline shaft that is rotatably supported in parallel with a laminated cam that is rotationally driven by a main shaft, and a screw pin that is rotatably and slidably supported by the shaft and that is screwed into a base portion. A cam follower engaged with the spiral groove of, and a bracket rotatably supported by a spline shaft so as to move integrally with the cam follower, and the movement of which is transmitted to the needle bar through a transmission mechanism. , A positioning cam fixed to the spline shaft, a spring that engages with the positioning cam and restrains the movement of the cam, and the spline shaft is rotatably operated. A zigzag sewing machine cam selection device comprising a manual operation mechanism for rotating the shaft around a spring, wherein a spring for engaging a positioning cam and restraining its movement is attached to the bracket. A.

Operation The movement of the positioning cam is restrained by the spring, but since the spring is attached to the bracket, the movement of the positioning cam is restrained with respect to the bracket and moves integrally with the bracket. Therefore, the movement of the cam follower causes the bracket, the positioning cam, and the spline shaft to swing together, and there is no relative movement between the cam follower and the spline shaft, so the cam follower moves axially. Never.

The movement of the spline shaft that swings integrally with the cam follower is transmitted to the manual operation mechanism. The transmission to the manual operation mechanism may extend to a manual operation member exposed on the front surface of the sewing machine such as a dial or an operation lever, but it is preferable to provide a play in the manual operation mechanism to absorb the movement linked to the spline shaft. It is desirable that it does not reach the manually operated member. Examples of the play include backlash of the gear transmission mechanism, endless bending of the belt, and a gap between the engaging members.

Embodiment One end of a leaf spring 31 is fixed to the tip of one arm 5a of the bracket 5, and the curved engaging portion 32 at the free end is engaged with the positioning cam 21 to restrain its movement. (Figs. 1 and 2).

In the case of this embodiment, the leaf spring 31 acts to restrain the cam 21 from rotating with respect to the bracket 5 by engaging the engaging portion 32 with the positioning cam 21, and at the same time, to mount the leaf spring. Cam 21 because the part is the tip of the arm
The bracket 5 is biased in the counterclockwise direction in FIGS. 1 and 2 by the reaction of being pressed against the cam 5, and the cam follower 10 is elastically contacted with the cam 2. Therefore, the conventional example shown in FIG. It is possible to omit the spring 25 provided in the above.

The manual operation mechanism for rotating the spline shaft 4 and moving the cam follower 10 in the axial direction is provided with a pinion 35 fixed to the spline shaft 4 and a sewing machine frame as shown in FIGS. The pinion 36 that is pivotally supported and a bevel gear 39 that meshes with the bevel gear 38 that is integral with the bevel gear 38 are fixed to the dial 41 that is attached to the end of the operating shaft 40 that projects toward the front of the sewing machine.
When the 41 is rotated, the spline shaft 4 is rotated by 90 ° through the gear transmission and the belt transmission, and the rotation of the spline shaft 4 due to the movement of the cam follower 10 is a toothed belt. It is absorbed by the slack of 37 and is not transmitted to the dial 41.

The laminated cam 2 may be fixed to the main shaft 1 so as to rotate integrally with the main shaft. However, in the illustrated embodiment, the internal gear 43 formed on one end of the differential gear, that is, the laminated cam 2 is formed.
The first eccentric cam 44 and the second eccentric cam 45 are externally fitted to the eccentric cam mechanism fixed to the main shaft 2 whose eccentric amount can be adjusted by the relative rotation of the cams 44, 45. The external teeth 46 have a smaller number of teeth than the teeth 43, and the rotational motion of the external teeth 46 causes the internal teeth 43 to be decelerated to N ₁ -N ₂ / N ₂ and rotationally driven. Here, N ₁ is the number of teeth of the inner teeth 43, and N ₂ is the number of teeth of the outer teeth 46.

Effect of the Invention The cam selection device of the present invention is configured as described above, and when the cam follower follows the cam to perform the swing motion, the spline shaft also swings integrally with the cam follower, and both Since there is no relative movement between them, the cam follower does not move in the axial direction as in the conventional one, and the movement of the cam follower following the cam is a swing in a plane. As a result, it is sufficient to increase the processing accuracy of the cam surface only in a narrow range where the cam follower slides, and the accuracy is not required in other areas, so that the cam can be manufactured easily and the manufacturing cost is reduced.

By providing a play for absorbing the movement of the spline shaft in the manual operation mechanism, it is possible to prevent the manual operation member from finely moving in association with the spline shaft and to maintain the stationary state.

In addition, the cam follower has a function of urging the bracket in one rotation direction by the reaction of the spring engaging with the positioning cam to stop the rotation of the cam and the reaction of being pressed against the positioning cam. The spring that makes elastic contact with the cam can be omitted.

[Brief description of drawings]

FIG. 1 is a perspective view of a main part of a cam selection device according to the present invention, FIG. 2 is a front view in which a part of the device is cut away, FIG. 3 is a plan view thereof, and FIG. 4 is A of FIG. -A sectional view taken along the line A, and FIG.
FIG. 6 is a sectional view taken along line B, FIG. 6 is a side view, FIG. 7 is a view showing a conventional example, and FIG. 8 is a view showing a locus of a conventional cam follower on a cam surface. 1 ... Main shaft, 2 ... Layered cam, 4 ... Spline shaft 5 ... Bracket, 6 ... Guide shaft, 7 ... Screw pin 8 ... Spiral groove, 10 ... Cam follower, 21 ... For positioning Cam, 31 ... leaf spring

Claims (3)

[Scope of utility model registration request] 1. A spline shaft that is rotatably supported in parallel with a laminated cam that is rotationally driven by a main shaft, and a screw pin that is rotatably and slidably supported by the shaft and that is screwed into a base portion of the spline shaft. A follower engaged with the spiral groove, a bracket rotatably supported by a spline shaft so as to move integrally with the cam follower, and the movement of which is transmitted to the needle bar through a transmission mechanism; A positioning cam fixed to the spline shaft, a spring that engages with the positioning cam and restrains the movement of the cam, and the spline shaft is rotated, and in conjunction with this, the bracket is attached to the spline shaft. A zigzag sewing machine cam selection device including a manual operation mechanism for rotating the zigzag sewing machine, wherein a spring for engaging a positioning cam and restraining its movement is attached to a bracket. Down of the cam selection device. 2. The manual operation mechanism has a teaching operation member exposed to the outside of the sewing machine, and a play is provided in the mechanism for connecting the manual operation member and the spline shaft to the spline shaft integrated with the cam follower. 2. The cam selection device for a zigzag sewing machine according to claim 1, wherein the movement is absorbed by the play and does not extend to the manually operated member. 3. A zigzag sewing machine cam selection device according to claim 1, wherein the spring urges the bracket in one rotation direction by the reaction of being pressed against the positioning cam, and makes the cam follower elastically contact the cam.