JPS6215024Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is based on an upper feed mechanism of a sewing machine in which the upper feed dog performs four movements consisting of back and forth movement and up and down movement, and feeds the cloth in cooperation with the lower feed dog.
The present invention relates to an upper feed mechanism that can adjust the stroke of the upper feed dog in the longitudinal direction and the vertical direction.

An upper feed mechanism is known that can adjust the longitudinal stroke of the upper feed dog, that is, the amount of feed of the upper feed dog. According to this mechanism, it is possible to correct and eliminate the difference in stitching between the upper and lower layers that occurs due to the influence of the presser foot by adjusting the feed amount of the upper feed dog. Even if you try to remove the fabric by raising the presser foot due to a thread breakage during sewing, etc., when the needle is rising, the upper feed dog is in its downward stroke, and the lower feed dog is also in its upward stroke, holding the fabric from above and below. It was not easy to take out the fabric, and if you tried to force it out, you could easily damage the fabric.

Another difficulty caused by the provision of the top feed mechanism is that it is difficult to handle fabrics that have stepped portions formed by overlapping portions of fabric or inserted interlining, etc., especially those that have extremely thick stepped portions. When sewing, there is a risk that when the upper feed dog ascends and performs the return stroke, it may catch on the stepped portion and cause fabric jams. Conventionally, when sewing fabrics such as those mentioned above, the mounting position of the upper feed dog was raised upwards to prevent it from getting caught on the stepped part during the return process, but it is necessary to set the mounting position of the upper feed dog appropriately depending on the fabric. It is extremely troublesome and difficult to change the upper feed dog to
The upper feeding mechanism is not able to perform its function at all or hardly at all in the fabric portions other than the stepped portions, resulting in a disadvantage. If the stroke in the vertical direction of the upper feed dog is set large in advance, it is possible to perform upward feed without getting caught at the stepped portion, but in this case, the following new problem arises. The larger the vertical displacement of the feed dog per unit time, the greater the vertical speed, which increases the impact force applied to the fabric, making it more likely that the fabric will be scratched by the feed dog. The vibration caused by the vertical movement becomes large. From this point of view, it is not desirable to increase the vertical stroke of the upper feed dog.

The purpose of this invention is to eliminate the above-mentioned drawbacks of the conventional upper feed mechanism, and for this purpose, a lever for lifting the upper feed arm is attached to the presser arm shaft that pivots the presser arm so that it can rotate in the vertical direction. However, when the presser foot is raised, the upper feed dog is also raised at the same time, and an adjustment mechanism is provided so that the vertical stroke of the upper feed dog can be adjusted.

To explain this using a drawing, the upper feed mechanism shown in the figure is used for an overlock sewing machine, and the upper feed mechanism includes a longitudinal movement mechanism and a vertical movement mechanism for the upper feed dog, respectively. It is illustrated in the figure. In other words, Fig. 1 shows the movement mechanism of the upper feed dog in the front-rear direction. An arc-shaped upper feed crank 6 is fixed to the feed drive shaft 5 to be moved.
The crank is connected to the upper feed shaft 7 by a fixed arm 8 and a link 9, and the swinging motion of the feed drive shaft 5 is transmitted by the crank lever mechanism consisting of the upper feed crank 6, the link 9, and the arm 8. The upper feed shaft 7 moves an upper feed arm 12 forward and backward in the feed direction by a crank 11 fixed to the shaft end, and has a free end of the arm facing the differential feed dog 2 and a presser foot (not shown). The upper feed dog 13 provided in the transparent window is moved back and forth in synchronization with the differential feed dog 2. The forward and backward stroke is adjusted independently from the lower feed dog by moving the slider 15 attached to the lower end of the link 9 along the upper feed crank 6, thereby eliminating the influence of the presser foot. The hollow shaft 1 rotatably fitted to the upper feed shaft 7 can eliminate the seams between the upper layer and the lower layer of the fabric that occur due to this.
A two-pronged lever 20 is fixed to the hollow shaft and has a fork at the tip fitted to a square piece 18 that is pivotally supported by a shaft 17 on a slider 15, and a two-pronged lever 20 is fixed to the hollow shaft and integrated with the two-pronged lever. An operating mechanism consisting of an interlocking operating lever 21 is provided. The operating lever 21 may be operated by directly grasping the protruding end of the operating lever protruding from the sewing machine frame; There is a risk that it will deviate from the adjusted position. In order to solve this problem, in the illustrated device, a dial 26 is screwed onto a stepped screw 25 attached to the operating lever 21 through an arc-shaped long groove 24 bored in a bracket 23 attached to the sewing machine frame. The operating lever 21 can be fixed in a predetermined position by tightening the lever (see FIG. 2).

The feed amount of the upper feed dog 13 can be adjusted by rotating the operating lever 21 as described above, but the distance between the front end of the upper feed dog disposed within the transparent window of the presser foot and the front edge of the transparent window is The starting position of the forward stroke of the upper feed dog should be kept constant so that the gap between the upper feed dog and the presser foot will not be enlarged by adjusting the feed amount, and the fabric will be caught between the gaps and cause fabric clogging. It is desirable to have a minimum and constant gap.

For this reason, the center of curvature of the upper feed crank 6 is aligned with the arm 8 and the link 9 when the differential feed dog 2 is at the start position of the forward stroke, where the feed amount is set to the maximum by a separately provided known adjustment device (not shown). axis attachment point 2
8, and when the slider 15 is moved along the upper feed crank by operating the operating lever at the start position of the forward stroke of the differential feed dog at the maximum feed amount, the link is activated. The arm 9 rotates about the pivot point 28 as a fulcrum, thereby keeping the arm 8 stationary.

Next, the movement mechanism of the upper feed dog in the vertical direction will be explained with reference to FIG.
The upper feed dog 13 at the free end is always urged toward the differential feed dog 2 by being pushed down by a spring-loaded roller 32 of the elastic device shown at 1; A crank pin 35 protruding from a crank 34 fixed to the swing shaft 33 engages with the upper feed arm via an attached leaf spring 36, and the swing movement of the swing shaft causes the upper feed arm 12 to move toward the crank 11. The upper feed dog 13 is rotated vertically using the crank pin as a fulcrum.
The vertical movement of the differential feed dog 2 is symmetrical to that of the differential feed dog 2. The swing motion of the swing shaft 33 is performed using a known drive shaft of the sewing machine as a drive source, and in the illustrated device, a knife shaft 39 of an upper knife 38 is used. Specifically, a block 41 that is swingably fitted to a crankshaft 40 that protrudes laterally from the female shaft 39 is fixed with a set screw 42, and the shaft is attached to pins 44, 44 that protrude on both sides of the block 41. Supported square pieces 45, 45
A two-pronged lever 46 protrudes laterally from the swing shaft 33.
(see Fig. 4).As a result, when the knife shaft 39 rotates counterclockwise and the upper knife 38 rises,
The swing shaft 33 rotates clockwise, and the crank pin 3
5 is lowered, the upper feed arm 12 is rotated downward by the action of the ammunition device 31, and the upper feed dog 13 is lowered. When the knife shaft 39 is reversed and rotated clockwise and the upper knife 39 is lowered, the upper feed dog 13 is raised. In this way, the upper feed dog 13 moves up and down by the rocking of the female shaft 39, and its stroke can be adjusted by changing the mounting position of the block 41 on the crankshaft. That is, when the set screw 42 is loosened and the block 41 is moved to the right side in FIG. 4, the female shaft 39 swings at a certain angle.
This is because the swinging range of the swinging shaft 33 becomes smaller, and conversely increases when the block is moved to the left. In the illustrated device, the groove into which the square piece 45 of the bifurcated lever 46 fits is formed so as to coincide with the crankshaft 40 located at the lower limit of the swing range (see FIG. 4).

Therefore, when the crankshaft 40 and the fork lever 46 are at their lower limits and the upper feed dog is in the lowered position, even if the square piece 45 is moved, the fork lever remains stationary and does not move. Even if the vertical stroke of the upper feed dog is changed, the lowering position of the upper feed dog can always be kept constant.

In the above-mentioned mechanism, instead of fixing the block 41 with the set screw 42 as described above, it is also possible to adjust the block 41 by, for example, an operating mechanism of the slider 15 as shown in FIG.

Alternatively, the crankshaft may be attached to the oscillating shaft side and the fork lever to the female shaft side, or the oscillating shaft may be connected to another operating shaft that oscillates in the same direction as the oscillating shaft via a crank lever mechanism, and the attachment point of the link connecting the crank and lever to the crank or lever may be adjusted so that the distance to the center of rotation of the crank or lever can be changed.

As mentioned above, the upper feed dog is lowered when the needle is raised, and in the lowest position, it is difficult to insert or remove fabric in that state. In order to solve this problem, a lever 51 is provided which is attached to a presser arm shaft 50 together with a presser arm 49 having a presser foot attached to its free end (only its base is shown in the figure). A roller 52 attached to the end is engaged with the upper feed arm 12 via the leaf spring 36. A lever 53 connected to a pedal (not shown) by a chain is fixed to the presser arm shaft 50 in a known manner. As a result, when the pedal is depressed, the presser arm shaft rotates and the presser arm 4
9, the upper feed arm 12 is lifted against the action of the elastic device, and the presser foot and the upper feed dog rise above the throat plate. In this way, the fabric can be inserted or removed without any problem.

As described above, the top feed mechanism of the present invention is designed so that when the presser foot is raised, the top feed dog also goes up at the same time, so there is no problem with loading and unloading the fabric, and the top feed dog also moves up. Since the stroke in the vertical direction can be changed, when sewing fabric without stepped sections, especially thin fabric, by reducing the above stroke, it is possible to prevent the fabric from being scratched by the feed dog. At the same time, it is possible to reduce the vibration caused by the vertical movement of the upper feed dog, and when sewing fabric with stepped sections, the above-mentioned stroke is increased and the upper feed is carried out in the forward stroke when descending. At the same time, it is possible to prevent the upper feed mechanism from getting caught on the stepped portion when ascending and performing the return stroke, thus eliminating the drawbacks of the conventional upper feed mechanism.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the back and forth movement mechanism of the upper feed dog in the upper feed mechanism, FIG. 2 is a sectional view of a part of the operating mechanism in the same mechanism, and FIG. 3 is a perspective view of the vertical movement mechanism of the upper feed dog. FIG. 4 shows a side view of the main parts of the mechanism. 2...Differential feed dog, 5...Feed drive shaft, 6...
Upper feed crank, 7... Upper feed shaft, 11... Crank, 12... Upper feed arm, 13... Upper feed dog, 1
5... Slider, 18... Square piece, 20... Forked lever, 21... Operating lever, 31... Bullet device, 33... Rocking shaft, 35... Crank pin, 3
9...Female shaft, 40...Crankshaft, 41...Block, 45...Square piece, 46...Forked lever, 4
9...presser arm, 50...presser arm shaft, 51...lever.

Claims (1)

[Scope of claim for utility model registration] (1) Crank 1 that swings in conjunction with the feed drive shaft 5
1, and is pivotally supported by the crank pin of the crank,
The upper feed arm 12 moves forward and backward in the feed direction due to the swinging motion of the crank 11, and is always urged to rotate downward by the action of a spring.The upper feed arm 12 is attached to the end of the arm facing the lower feed dog 2. upper feed dog 13
and includes a swing shaft 33 that swings in conjunction with an operating shaft 39 of the sewing machine, and in conjunction with the swing of the swing shaft, the upper feed arm 12 swings in the vertical direction about the crank pin as a fulcrum, In the upper feed mechanism of a sewing machine, which has a vertical motion mechanism that causes the upper feed dog to move up and down symmetrically with the lower feed dog, the presser arm and the upper and lower parts are connected to a presser arm shaft 50 that pivotally supports a presser foot arm 49 that carries a presser foot. A first lever 51 is provided so as to rotate together with the presser foot when the presser foot is raised. A four-bar link mechanism such as a slider crank mechanism or a crank lever mechanism connects the operating shaft 39 and the swinging shaft 33 and transmits the movement of the operating shaft 39 to the swinging shaft 33. An adjustment means for adjusting the amount of rocking of the rocking shaft is provided inside, and when the amount of rocking of the rocking shaft is changed by the adjusting means, the vertical stroke of the upper feed dog changes. Feeding mechanism. (2) The four-bar linkage mechanism equipped with adjustment means is operated by the operating shaft 3.
9, a crankshaft 40 fixed to one of the swing shafts 33, and a forked lever 46 fixed to the other,
The upper feed mechanism according to claim 1, comprising sliders 41 and 45 which are slidably fitted into the fork 47 of the fork lever 46 and are attached to the crankshaft 40 so that their position can be adjusted. (3) The slider consists of a block 41 which is fixed to the crankshaft so that its position can be adjusted, and a square piece 45 which is integral with the block and slidably fits into the fork 47. Top feed mechanism as described. (4) The upward feed mechanism according to claim 3, wherein the direction of the groove of the fork 47 is set to match the direction of the crankshaft 40 when the crankshaft reaches the lower limit of the swing range. (5) The four-bar linkage mechanism equipped with adjustment means is operated by the operating shaft 3.
9 and a crank fixed to one of the swing shafts 33, a lever fixed to the other, and one end slidably connected to either the crank or the lever, so that the distance to the center of rotation can be adjusted. 2. The upper feed mechanism according to claim 1, comprising a link whose other end is connected to the other of the crank or lever. (6) Between the feed drive shaft 5 and the crank 11, there is an upper feed crank 6 fixed to the feed drive shaft, an upper feed shaft 7 fixed to the crank 11, an arm 8 fixed to the upper feed shaft, and one end. A transmission device is provided which includes a link 9 which is pivotally attached to the arm and whose other end is pivotally attached to a slider 15 which is movably attached to the upper feed crank, and which is rotatably supported on the upper feed shaft. The upper feeding mechanism according to claim 1, wherein an operating mechanism for moving a slider including an operating lever 21 is provided. (7) The upper feed crank 6 has an arc shape, and the center of curvature coincides with the pivot point 28 of the arm 8 and the link 9 when the lower feed dog is in the most forward position. Top feed mechanism. (8) A screw 25 is attached to the operating lever 21 through a long arc-shaped groove 24 formed in the bracket 23.
7. The upper feed mechanism according to claim 6, wherein the operating lever is crimped and fixed to the bracket by screwing in the dial 26 which is screwed onto the screw.