JPH0436795Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates to an upper feed mechanism of a sewing machine in which an upper feed dog that performs four movements, including forward and backward movement and up and down movement, feeds cloth in cooperation with a lower feed dog.

Prior Art This type of top feed mechanism is well known, and in most cases, as shown in FIG. A crank 2 that swings back and forth on a shaft, an upper feed table 4 that is rotatably supported by the crank 2 in the vertical direction and has an upper feed dog 3 attached to its free end, and an upper feed table. The crank pin 7 is fixed to the upper feed vertical shaft 6 that swings in conjunction with the main shaft 10 and swings up and down, and the crank pin 7 moves from the bottom of the upper feed base 4. The upper feed dog 3 performs four movements consisting of back and forth movement and up and down movement by the rocking motion of both cranks 2 and 8, and cooperates with the lower feed dog 9 to feed the cloth. I am trying to get them to do this.

FIG. 4 shows the locus of the upper feed dog in this type of upper feed mechanism, and the section AB indicates the section in which the upper feed is performed, that is, the amount of upper feed. Incidentally, at point a, the upward feed amount is 0. The type shown in Japanese Patent Application Laid-Open No. 52-86844, Utility Model Application Publication No. 56-11772, etc., in order to perform upward feeding between AB,
The crank pin 7 separates from the upper feed table 4 at point B, and
It is designed to engage at a point and lift the upper feed table 4 against the action of the spring device 5, but in order to eliminate the collision noise generated when the crank pin 7 pushes up the upper feed table 4, the collision is prevented. Some models have the sound source housed within the body of the sewing machine, which has a sealed structure. The one shown in Japanese Patent Application Laid-Open No. 59-105490, ie, the one shown in FIG. is adapted to engage with the other clutch piece 13.

Problems that the invention aims to solve In any case, in the conventional upper feed mechanism, the upper feed dog traces a trajectory as shown in Fig. 4, but the length between A and B, which is the working surface of the upper feed dog, The feed amount increases as the working surface becomes higher and decreases as the working surface becomes lower, and as it changes depending on the height, the following problems arose.

The reason is that the feeding efficiency differs depending on the thickness of the cloth. That is, when the cloth is thick, the working surface becomes high and the amount of cloth feeding becomes large, and conversely, when the cloth is thin, the working surface becomes low and the amount of cloth feeding becomes small, and when the cloth is thin, the feeding efficiency becomes poor. Here, the feed efficiency refers to the ratio of the actual cloth feed amount (between AB) to the total back-and-forth movement of the upper feed dog (between CD).

Feeding efficiency can be increased by raising the working surface of the upper feeding dog, but in this case, the amount of rise from the working surface of the upper feeding dog becomes small, so when feeding fabric with thick or stepped parts, The thick part or stepped part may get caught on the upper feed dog, or the thick part,
Problems such as uneven seam pitches occur in the stepped portions.

In addition, in order to feed thin fabrics efficiently, if the working surfaces of the upper and lower feed dogs are brought closer to line C-D in Figure 4, the engagement of the upper and lower feed teeth will become deeper, which may cause feeding scratches on the fabric or empty rings. There was a problem in that it produced a loud impact sound during formation.

Even if the design of the longitudinal feed mechanism and the vertical feed mechanism is simply changed, the basic form of the locus shown in FIG. 4 will not change, and sufficient effects will not be achieved.

The purpose of the present invention is to provide a top feed mechanism with high feed efficiency that can obtain a substantially constant top feed amount even if the thickness of the fabric, that is, the height of the working surface of the top feed dog varies.

Means for Solving the Problems Therefore, the present invention provides a cam means on the upper feed base so that the locus of the upper feed dog becomes as square as possible at the lower side, and a sliding member provided on the crank for the cam means. are slidably engaged.

In other words, the present invention includes an upper feed table that is pivotably supported vertically by a member that reciprocates in the feed direction in conjunction with the main shaft, and has an upper feed dog at its free end that faces the lower feed dog; In an upper feed mechanism of a sewing machine having a vertical movement mechanism including a crank that swings vertically in conjunction with the upper feed table and engages with the upper feed table to move the feed table up and down, the upper feed table includes a downwardly inclined part and cam means having an upwardly sloping portion, and the crank is provided with a sliding member that slidably engages the cam means, and when the crank is rotated downwardly, the sliding member engages with the downwardly sloping portion of the cam means. A further feature is that when the crank rotates upward, it engages with each of the upwardly inclined portions.

The cam means is provided so as to engage the sliding member from above the sliding member, or from both the upper and lower sides of the sliding member. The former type is suitable for use in the first type of upper feed mechanism shown in the above-mentioned Japanese Patent Application Laid-open No. 52-86844, Utility Model Application No. 56-11772, etc., and the latter one is shown in FIG. Suitable for use with the second type of top feed mechanism.

The cam means may also be a cam groove formed on the upper feed table or a convex portion formed integrally with the upper feed table, or it may be formed as a separate member from the upper feed table and attached to the upper feed table. It may be possible to do so. In any case, the cam means itself, the member provided with it, or the upper feed table can be replaced with the most suitable one depending on the structure, shape, and dimensions of the upper feed mechanism, or the properties and conditions of the fabric to be sewn. It is desirable to do so. If the upper feed dog makes four movements while drawing an ideal trajectory, and the lower side of the trajectory can be used as the working surface of the upper feed dog,
If the cam means or the member provided with the cam means is replaced depending on the thickness of the cloth, the collision noise can be eliminated in the first type because there is no need to separate the sliding member from the cam member. In addition, there is no need to provide a spring device that acts to push down the upper feed table. Also, since the second type does not require a clutch mechanism, the structure is simplified and the spring device can be omitted as in the above case.

Function When the crank rotates downward toward the bottom dead center, the sliding member slides on the downward slope, causing the upper feed base to move forward in a vertically stationary state. Perform a nearly horizontal feed motion on the teeth. Similarly, when the crank rotates upward after passing through the bottom dead center, the upper feed dog performs a substantially horizontal feed movement. Figure 3 shows the locus drawn by the upper feed dog based on this mechanism.

Embodiment FIG. 1 shows the upper feed table 4 of the upper feed mechanism shown in FIG.
This figure shows a guide member constituting the cam means for the crank pin 7 attached to the upper and lower backing plates 15.
are combined into a fork shape and attached to the upper feed table 4 with a set screw 16, and a cam groove 17 consisting of an upwardly curved inclined part 17a and a downwardly curved inclined part 17b is formed between the backing plates. The crank pin 7 is slidably fitted therein.

In FIG. 1, the pin 7 swings upward and downward in an arcuate manner, and the upper feed table 4 moves back and forth while being moved up and down by the pin 7, and performs a cloth feeding action in the left and right strokes. For convenience of explanation, the movement of the relative position of the pin 7 with respect to the upper feed table 4 is indicated by arrows.
, is shown.

FIG. 3 shows the locus of the upper feed dog in the above embodiment. As the crank 8 rotates downward from the top dead center, the upper feed table 4 moves forward (to the right in FIG. 1). As a result, as shown in FIG. 1, when the crank pin 7 is sliding on the downward slope 17b, the upper feed dog 3 moves forward and descends, drawing a trajectory from point b in the direction of the arrow. A stage in which the crank 8 is still rotating downward toward the bottom dead center, and the upper feed table 4 moves forward and then reverses and retreats, thereby causing the crank pin 7 to slide in the opposite direction on the downward slope 17b. In this case, since the upper feed carriage 4 moves backward in a vertically stationary state, the upper feed dog 3 draws a trajectory in which it performs a substantially horizontal feed movement toward point c. The upper feed table 4 continues to move backward, and the crank 8 passes through the bottom dead center and rotates upward.
At the stage when the crank pin 7 slides on the upwardly inclined portion 17a, the upper feed bar 4 remains almost stationary in the vertical direction and retreats, so the upper feed dog 3 also remains almost stationary after passing through point c.ゞDraw a trajectory for horizontal feed motion. As the crank further rotates upward, the upper feed table 4 retreats, then reverses and moves forward, and at the stage where the crank pin 7 slides in the opposite direction on the upward slope 17a, the upper feed dog 3 moves upward. Move forward and draw a trajectory toward point b.

Effects of the invention As described above, the upper feed mechanism of this invention is provided with a cam means consisting of a downwardly inclined part and an upwardly inclined part on the upper feed table, so that the crank rotates downward and then rotates upward. In the required section, the upper feed table is moved in the vertical direction by sliding the sliding member provided on the crank along the downward slope when the crank rotates downward, and along the upward slope when the crank rotates upward. The machine is moved forward in a nearly stationary state, and the upper feed dog performs a nearly horizontal feed motion to draw a trajectory as shown in Figure 3. Even if the thickness of the upper feed dog differs, that is, the height of the working surface of the upper feed dog, a substantially constant feed amount can be obtained and the feed efficiency is also high. The above effect can be obtained just by providing the structure, and there is no need to make major changes to the conventional mechanism.

[Brief explanation of the drawing]

Figure 1 is a front view of a guide member constituting the cam means provided on the upper feed base of the upper feed mechanism shown in Figure 2, Figure 2 is a perspective view of the upper feed mechanism, and Figure 3 is the upper feed of the present invention. FIG. 4 is a diagram showing the trajectory of the upper feed dog in a conventional example. 3...Upper feed dog, 4...Upper feed base, 6...Upper feed vertical axis, 7...Crank pin, 8...Crank, 9...Lower feed dog, 11...Clutch mechanism, 1
5...Packing plate, 17...Cam groove.

Claims (1)

[Claims for Utility Model Registration] (1) A member that reciprocates in the feed direction in conjunction with the main shaft is pivotally supported so as to be swingable in the vertical direction, and the free end is provided with an upper feed dog opposite to the lower feed dog. In the upper feed mechanism of a sewing machine, the upper feed mechanism includes an upper feed table, and a vertical movement mechanism including a crank that swings in the vertical direction in conjunction with the main shaft and engages with the upper feed table to move the feed table up and down. providing a cam means having a downwardly inclined portion and an upwardly inclined portion on the feed base;
The crank is provided with a sliding member that slidably engages the cam means, and when the crank rotates downwardly, the sliding member engages the downwardly inclined portion of the cam means.
An upper feed mechanism characterized in that when a crank rotates upward, it engages with each upwardly inclined portion. (2) The upper feeding mechanism according to claim 1, wherein the cam means engages the sliding member from above. (3) The upper feed mechanism according to claim 1, wherein the cam means engages the sliding member from both upper and lower sides. (4) The first registered claim is that the cam means itself or together with the member on which it is provided is replaceable.
Upper feed mechanism as described in section.