JPS5933340Y2 - Sewing machine feed dog drop device - Google Patents

Description

[Detailed Description of the Invention] (Technical Field) The present invention relates to a feed dog drop device for a sewing machine that can be operated safely even while the sewing machine is in operation, has a simplified mechanism, and is easy to assemble.

(Prior art) Various types of feed dog drop devices for conventional sewing machines have been proposed, and the main ones are listed below: a. Plunger movement method; b. Vertical feed that engages the vertical feed cam. Method C: Switch the lever held by the arm and engaged with the feed table to the cloth feed state, and engage the feed table with the feed dog in the dropped state.C. This is the opposite of the dc method, in which the upper and lower feed cams are moved relative to the upper and lower feed arms, but methods a and b are mechanisms that are used less frequently. All of them generally have the disadvantage of being complex in structure.

Method C is an undesirable method in terms of operation because it requires moving the swinging vertical feed arm while the sewing machine is in operation.

Similarly to methods a and b, method d also has the disadvantage of a complicated structure.

(Purpose) The purpose of the present invention is to move the vertical feed cam that swings the vertical feed arm with respect to the vertical feed arm, as shown in the method d of the prior art, to make the feed dog drop device of the sewing machine move up and down. It is an object of the present invention to provide a system in which the feed is inactive, which can be safely operated even while the sewing machine is in operation, has a simpler mechanism than conventional ones, and is easy to assemble.

(Example) The present invention will be explained below with reference to examples.

The horizontal feed arm 1 is pivotally connected between a pair of centers 3 and 3' fixed to the free arm bed 2, and a feed dog 5 is attached to a pair of pins 4 (the other not shown) fixed to the horizontal feed arm. A fixed feed table 6 is pivotally mounted, and the feed table is constantly fed horizontally via a horizontal feed arm 1 which is oscillated by the rotation of a horizontal feed cam (not shown) by an amount corresponding to the adjustment of a feed adjuster. is vertically fed by the vertical feed cam 7 that comes into contact with the feed base, and both feeds are combined to cause the feed dog 5 to perform a so-called four-feed motion.

The shaft 8 is pivotally connected to a bush 9 fixed to the bearing portion 2a of the free arm bed 2, and the vertical feed cam 7 has a keyway 7a engaged with the head 10a of a pin 10 driven into the shaft 8. It rotates together with the shaft 8, is slidable in the axial direction, and is biased by a spring 11 from the flange portion 7b side.

A cover 12 that is fixed to the free arm bed 2 with screws 20 and covers the lower part of the bed is formed with a pin portion 12a. A lever 15 is pivotally mounted.

One end of the lever protrudes into a recess 12b formed on the outside of the cover 12 so that it can be operated externally, but it does not protrude from the other contours of the cover 12 so as not to interfere with pipe stitching. It is provided with a pin 15a that acts on the flange 7b of the vertical feed cam 7 near the middle as will be described later, and is made up of a spring 16 and a sphere 17 and engages with locking grooves 12c and 12d formed in the cover 12. Locking mechanism 18
, and the lever can be switched to a predetermined position with moderation.

The lever 15 also has a fan-shaped notch 15b, and a projection 12e formed on the cover 12 limits the rotation range of the lever.

Next, referring to FIGS. 5 and 6, the vertical feed cam 7 also has a minimum lift portion indicated by a radius R in the axial direction of the sliding surface 7c with the engagement surface 6a of the feed base 6. The point in the middle of the length range and the shortest distance R' from the axis to the axis is smaller than the radius R of the minimum lift part, and the vertical line E of the end perpendicular to the longitudinal direction of the vertical feed cam is gentle. They are connected by an inclined surface 7d.

The engagement surface 6a of the feed bar 6 normally comes into contact with the vertical feed cam 7 and is moved up and down, but when the feed dog 5 drops from the upper surface of the throat plate 19 (described later), the feed bar 6 is attached to the free arm bed 2. The upper end of the stopper screw 21 is brought into contact with the upper end of the stopper screw 21.

The position of the upper end of the screw 21 in FIG. 4 is adjusted so that the engagement surface 6a is located within a distance greater than R' and less than R from the center of the shaft 8 when it comes into contact with the feed base 6.

(Operation) Next, the operation of the present invention configured as described above will be explained.

The vertical feed cam 7 can be assembled in the same manner as conventional ones of this type, and the lever 15 can be assembled by removing the cover 12 from the free arm bed 2, assembling the locking mechanism 18, and attaching the bearing 14. After the lever 15 has been assembled, the cover 12 can be easily assembled to the free arm bed 2 using the screws 20.

Next, to explain the operation of the vertical feed device, as shown in FIG.
5a does not act on the flange portion 7b, the vertical feed cam 7 is biased to the position shown in the figure by the biasing force of the spring 11, and the rotation of the vertical feed cam 7 causes the engagement surface 6a on the feed base 6.
Vertical feed acts through.

Next, when the lever 15 is rotated about the bearing 14 against the urging force of the spring 11, the pin 15a moves the vertical feed cam 7 to the left in the figure via the flange portion 7b, and the sphere 17 is locked. When the shaft 8 is engaged with the groove 12d, the shaft 8 is exposed below the engagement surface 6a, but the feed bar 6 comes into contact with the upper end of the screw 21,
In this state, the feed dog 5 drops from the upper surface of the throat plate 19.

In this state, the engaging surface 6a is located within the distance range R' and R from the center of the shaft 8, so to return to the cloth feeding state, the lever 15 must be rotated around the bearing 14 and the sphere 17 When the vertical feed cam 7 is engaged with the locking groove 12c, the biasing force of the spring 11 pushes the vertical feed cam 7 to the right in FIG. It is possible to return to the position shown in the figure (horizontal position).

These operations can be performed safely even while the sewing machine is in operation.

(Effects) As described above, according to the feed dog drop device of the present invention, it can be operated safely even while the sewing machine is running, the mechanism can be simplified compared to conventional devices, and it can be easily assembled. effective.

[Brief Description of the Drawings] The drawings relate to an embodiment of the present invention, and FIG. 1 is a plan view of the free arm bed seen from the opposite side of the throat plate surface, and FIG. 2 is a partial view of the cover from FIG. 1. 3 is a longitudinal sectional view of the main part shown in the direction of arrow A in FIG. 2, and is shown upside down according to the usage condition of the sewing machine; FIG. 4 is a cross-sectional view of the main part shown in FIG. Fig. 5 is a cross-sectional view showing details of the main part of Fig. 3, and Fig. 6 is a longitudinal cross-sectional view of the main part of Fig. FIG. 3 is a cross-sectional view showing the main part in the direction of arrow C in the figure. 2 is a free arm bed, 5 is a feed dog, 6 is a feed stand, 7
1 is a vertical feed cam, 8 is a shaft, 12 is a cover, 12b is a recess, 12c and 12d are locking grooves, 15 is a lever, 15a is a pin, and 18 is a locking mechanism.

Claims (1)

[Scope of utility model registration request] a vertical feed cam slidably attached to a shaft so as to be engaged and disengaged from a feed table having a feed dog in a cloth feeding state;
A pin that acts on the vertical feed cam is provided near the center, and is pivotally connected to a cover that covers the lower part of the free arm bed of the sewing machine, with one end protruding outside the cover, and a locking groove and a step formed in the cover. A feed dog drop for a sewing machine, which is a switching device using a lever equipped with a locking mechanism that engages with the needle, and is characterized in that the operating part of the lever that projects outside does not extend beyond the outline of the free arm bed. Device.