JPH0333354B2 - - Google Patents

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention is applicable to sewing machines such as embroidery sewing machines, basting sewing machines, pattern sewing machines, etc., in which the presser foot and the feed dog do not cooperate when moving the cloth. Regarding sewing machines.

(Prior Art) Sewing machines are equipped with a cloth presser foot to press the cloth against the throat plate below the needle, but since it is necessary to move the cloth against the throat plate (sewing machine needle),
The presser foot presses the fabric with a relatively strong force while the sewing machine needle passes through the fabric, and weakens or releases the presser force while the sewing machine needle is out of the fabric so that the fabric can move smoothly. There is a need. That is, it is necessary to change the pressing force of the presser foot in conjunction with the vertical movement of the sewing machine needle.

Therefore, in the past, for example,
As disclosed in the publication, a needle bar is passed through the presser foot, and a compression coil spring is inserted between the upper side of the presser foot and a presser ring fixed to the needle bar. A pull-up ring is fixed to the needle bar on the lower side, and when the needle bar (sewing machine needle) is driven downward, the presser foot is driven downward via a compression coil spring, and when the needle bar is driven upward, the pull-up ring is used to drive the presser foot downward. The presser foot is pushed upward. According to this, when the sewing machine needle is lowered to the lowest position, the presser foot at the lower end of the presser foot presses down the cloth with the strongest force, and when the sewing machine needle is at the highest position, the presser foot is also at the highest position. in position.

Further, as disclosed in Japanese Utility Model Application No. 62-3106, one leg of a scissor-shaped spring is engaged with a presser foot, the other leg is engaged with an arm extending below the needle bar, and the needle bar is A pin is installed to push down this arm.
When the needle bar descends to a certain extent, the pin hits the arm and rotates it counterclockwise. As a result, the scissor-shaped spring is compressed and its repulsive force is applied to the presser foot, increasing the pressing force of the presser foot. When the needle bar moves upward, the pin moves above the arm,
The arm is rotated clockwise by a scissor-shaped spring and returns to the standby position.

(Problems to be Solved by the Invention) In the presser foot device disclosed in the above-mentioned Japanese Utility Model Publication No. 61-7660, since the lifting ring collides with the presser foot and the presser foot moves up and down, the impact A sound is generated. During high-speed operation, the followability of the presser foot becomes poor, causing the presser foot to jump. When the sewing machine needle is raised, the presser foot is also raised, making it difficult to see where the needle drops, making it difficult to set the fabric in the correct position, and when threading the needle or replacing the needle. The presser foot gets stuck.

Furthermore, in the presser device disclosed in Japanese Utility Model Application Publication No. 62-3106, the pin collides with the arm, producing a large impact noise, and the arm vibrates up and down at the needle base, which is dangerous for the stitchers. Jumping of the presser foot is also a problem when sewing at high speeds.

Furthermore, depending on the thickness and material of the fabric, there are various appropriate values for the relative position between the vertical movement of the needle and the force for pressing down on the cloth by the presser foot, and there are also various appropriate values for the force for pressing down on the cloth. None of these can be adjusted.

In order to improve the efficiency of sewing, automatic high-speed sewing (industrial) sewing machines are being rapidly put into practical use. However, what is essential for this type of sewing machine is the ability to handle sewing items that are moved by a cloth feeder, etc. On the other hand, it is desirable to have a device that presses the cloth with a pressing force that matches the sewing timing of the sewing machine needle. However, the conventional presser foot device gives the presser a large vertical movement or jumps at high speeds, and does not provide a pressing force that matches the sewing timing at high speeds.

The first object of the present invention is to prevent or reduce the impact noise caused by the presser foot, and the second object is to provide a presser foot device suitable for high-speed sewing. A third object of the present invention is to provide a presser foot device capable of adjusting the phase of the pressing force relative to the top and bottom of the sewing machine needle and adjusting the pressing force.
The purpose of

[Structure of the invention]

(Means for Solving the Problems) The presser foot device of the present invention has a presser foot that is supported on a machine frame so as to be slidable vertically parallel to the needle bar and has a presser foot at the bottom; a coil spring whose lower end presses the presser bar; a spring presser located inside the machine frame and pressing the upper end of the coil spring; A motion converting mechanism is provided that drives the spring presser back and forth once in the vertical direction in synchronization with the vertical movement of the needle bar during one revolution of the shaft.

(Function) A spring presser located inside the machine frame presses down the upper end of the coil spring, and the lower end of this coil spring presses the presser rod downward. In the machine frame, a motion conversion mechanism converts the rotation of the upper shaft of the sewing machine into vertical movement of the spring presser foot. This vertical movement intermittently compresses the coil spring, and this compressive force is applied to the presser foot via the presser foot rod. Therefore, the sewing machine needle moves up and down in conjunction with the rotation of the upper shaft, and in synchronization with this, the spring member expands and compresses, and the repulsive force of the spring is applied to the presser foot, causing the presser foot to move against the fabric. Pressing force changes smoothly from low to high. The spring presser intermittently hits the upper end of the coil spring, but since the coil spring contracts, the impact noise is small, and there are no particularly dangerous mechanical elements outside the machine frame, that is, around the needle of the sewing machine.
When sewing is performed at high speed, the spring member vibrates (compresses/expands) at high speed. That is, it vibrates in synchronization with the rotation of the upper shaft, but since the presser foot bar is constantly lowered, it does not jump, and only receives vibrations from the pressing force. This vibration causes rotation of the upper shaft (i.e. vertical vibration of the needle bar)
Since it is synchronized with , cloth feeding is also carried out smoothly. The presser foot is always on the throat plate, so
The needle drop is easy to see, making it easy to accurately position the fabric. Further, the presser foot does not get in the way when threading the thread through the needle hole or when changing the needle.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

Embodiment FIG. 1 shows a side view of an embodiment of the present invention, and FIG.
The front view is shown in the figure, and the exploded perspective view is shown in Fig. 3. In these drawings, reference numeral 1 denotes a sewing machine frame, which is supported at its left end (not shown) by the base of the sewing machine so as to be rotatable within a limited narrow angular range. With this, for example, when inserting cloth between the lower end of the presser foot 22 and the throat plate (not shown), the machine frame 1
The part shown in FIG. 1 can be moved upwardly relative to the throat plate.

A circular eccentric cam 2 is fixed to an upper shaft 3 of the sewing machine within a machine frame 1 with a set screw 4. The eccentric cam 2 is loosely fitted into a cam follower ring 5a of the connecting rod 5, and rotates within the ring 5a. A pin 6 is inserted into a hole at the tip of the connecting arm 5b of the continuous rod 5, and the pin 6 can rotate within the hole. pin 6
The tip is inserted into a hole at one end of the driven arm 8, and is fixed to the driven arm 8 with a set screw 7.

A drive shaft 9 passes through a hole at the other end of the driven arm 8, and the driven arm 8 is fixed to the drive shaft 9 with a screw 11. The drive shaft 9 also passes through a hole in one end of the drive arm 10, and the drive arm 10 is fixed to the drive shaft 9 with a screw 12.

The drive shaft 9 is rotatably supported by the boss portions 1b and 1C of the machine frame 1, and is prevented from coming off by an E ring 27 and the drive arm 10.

A spring retainer 15 is installed in the hole at the other end of the drive arm 10.
A pin 14 passes through the hole, and the drive arm 10 is fixed to the pin 14 with a set screw 13. The pin 14 can rotate relative to the spring retainer 15.

The lower part of the spring retainer 15 is tapered 15b and becomes a narrow rod 15a at the lower end, which passes through the hole of the spring receiver 18. The spring receiver 18 has a flange 1a, and the spring receiver 18
The small diameter cylindrical part enters the inner space of the upper end of the coil spring 17, and the flange 18a
is in contact with the upper end surface of. In other words, the spring receiver 18
is placed on the upper end of the spring 18, and the tapered surface 1 of the spring retainer 15 is placed on the entrance edge of the hole of the spring receiver 18.
5b comes into contact.

The presser rod 16 is attached to the lower half of the coil spring 17.
The upper end of the presser bar holder 19 is fixed to the presser bar 16 with a screw 20. This presser bar holder 19 supports the lower end of the spring 17. The presser bar holder 19 is a spring presser 15
Press the presser rod 16 so that the spring receiver 18 is located within the range of the amplitude of the vertical reciprocating motion of the tapered surface 15b.
is fixed to.

A guide groove 19a is formed in the presser bar holder 19, and a rotation stopper pin 2 fixed to the machine frame 1
1 passes through this guide groove 19a.

The presser bar 16 is supported by the machine frame 1 in a vertically movable manner and extends outside (downward) of the machine frame. A presser foot 22 is fixed to its lower end with screws 23.

The upper shaft 3 of the sewing machine passes through the circular eccentric cam 2, and a known thread take-up crank 24 is fixed to the tip thereof. A needle bar 25 is connected to the upper shaft of the sewing machine through a well-known needle bar crank (not shown), a needle bar crank rod, and a needle bar holder, and a sewing machine needle 26 is fixed to the lower end of the needle bar 25. Needle bar 26
The presser rods 16 and 16 each extend vertically.

Next, the operation of the above-mentioned presser foot device will be explained. As the upper shaft 3 rotates, the drive shaft 9 undergoes clockwise rotation within a predetermined angle range and subsequent counterclockwise rotation within a predetermined angle range via the eccentric cam 2, connecting rod 5, and driven arm 8. dynamic rotation,
do. A spring retainer 15 is rotatably connected to one end of the drive arm 10 by the swinging rotation of the drive shaft 9.
makes a reciprocating motion up and down. This vertical movement causes
The spring receiver 18 is intermittently pressed, and this pressing force is transmitted to the presser foot 22 via the presser bar holder 19 and the presser rod 16, and the presser foot 22 intermittently presses the sewing product without rising.

The spring presser 15 hits the coil spring 17
Since it is a spring receiver at the upper end of the spring, the noise caused by this collision is extremely small. Since the coil spring 17 rests on the presser bar holder 19, even if the coil spring 17 bounces, the presser bar holder 19 and the cloth presser bar 16 will not bounce. In other words, the presser foot 22 does not jump.

In this embodiment, the presser force is increased by loosening the screw 20, moving the presser bar holder 19 upward relative to the cloth presser bar 16, and then tightening the screw 20 again. In other words, the presser bar holder 19
The presser force can be adjusted by adjusting the position of the presser foot with respect to the presser rod 16.

Further, by loosening the screw 12 to adjust the angle formed by the drive arm 10 with respect to the driven arm 8, and then tightening the screw 12, the holding force can be similarly adjusted. In this embodiment, in order to facilitate such adjustment, an opening 1a is formed in the machine frame 1, and a screw 12 is exposed in this opening 1a.

Further, in this embodiment, the mounting angle of the circular eccentric cam 2 with respect to the upper shaft 3 can be adjusted using the screw 4. That is, from the eccentric cam 2 to the connecting rod 5
Remove the cam follower ring 5a, loosen the screw 4, rotate the cam 2 relative to the upper shaft 3, and then tighten the screw 4 again.
Tighten. As a result, the relationship between the cloth pressing force and the rotation angle of the upper shaft becomes, for example, a curve shown by a solid line in FIG. 4, and this curve moves to the left or right. That is, the application timing of the pressing force (the phase of the pressing force with respect to the vertical movement of the sewing machine needle) can be adjusted.

Next, other embodiments or modifications of the present invention will be described. In the above embodiment, a screw hole is made in the circular cam surface of the circular eccentric cam 2, a screw 4 is screwed into the hole, and the cam 2 is fixed to the upper shaft 3 with the screw 4. Therefore, as described above, when adjusting the application timing of the pressing force, the cam follower ring of the connecting rod 5 must be removed from the cam 2.

In another embodiment of the present invention, as shown in FIG. 5a, the circular eccentric cam 2 has a boss 2a formed integrally with the circular cam portion and protruding from a flat surface. A screw hole is made and a screw 4 is screwed into the hole to fix the cam 2 to the upper shaft 3 of the sewing machine. A state in which the connecting arm 5 is connected to the circular cam 2 is shown in FIG. 5b. In this embodiment, when the circular eccentric cam 2 is assembled into the machine frame 1 as shown in FIG. 1, the boss 2a of the circular eccentric cam 2 is located between the connecting arm 5 and the balance crank 24, and the connecting arm 5 from the cam 2, insert a screwdriver through the opening 1a (Fig. 2) and loosen the screw 4 to adjust the angle of attachment of the cam 2 to the upper shaft 3 of the sewing machine, that is, the timing of application of the pressing force. can.

〔Effect of the invention〕

As described above, according to the presser foot device of the present invention, the presser foot is always in the lower position and does not substantially vibrate up and down.
There is no impact noise between the presser foot and the throat plate, and the presser foot does not jump even during high-speed operation. Since the presser foot is always on the throat plate, it is easy to see the needle drop and set the fabric, and the presser foot does not move when threading the thread through the needle hole or changing the needle.

[Brief explanation of the drawing]

FIG. 1 is a side view of one embodiment of the present invention, FIG. 2 is a front view, and FIG. 3 is an exploded perspective view. FIG. 4 is a graph showing the relationship between the rotation angle of the upper shaft 3 of the sewing machine and the pressing force applied to the sewing material by the presser foot 22 in the embodiment shown in FIGS. 1 to 3. Figure 5a shows another example of the present invention.
FIG. 5b is a perspective view showing the external appearance of the circular eccentric cam 2 of the second embodiment, and FIG. 5b is a perspective view showing the state in which the connecting rod 5 is connected to the eccentric cam 2. 1: Machine frame (machine frame), 2: Circular eccentric cam (eccentric cam), 3: Sewing machine upper shaft (sewing machine upper shaft), 4: Set screw (fixing tool), 5: Connecting rod (connecting body), 5
a: Cam driven ring (cam driven body), 5b: Connection arm (connection arm), 6: Pin, 7: Set screw, 8: Followed arm (driven arm), 9: Drive shaft (drive shaft), 10: Drive Arm (drive arm), 1
1: Screw, 12: Screw (fixing tool), 13: Set screw, 14: Pin, (2 to 14: Movement conversion mechanism,
5-14: Link mechanism), 15: Spring presser (spring presser), 16: Fabric presser bar (presser bar), 17: Coil spring (coil spring), 18: Spring receiver, 19: Presser bar holder, 20: Screw , 21: Rotation stopper pin, 22: Cloth presser foot (cloth presser foot), 23: Screw,
24: Balance crank, 25: Needle bar (needle bar), 2
6: Sewing machine needle, 27: E-ring.

Claims (1)

[Scope of Claims] 1. A presser bar that is supported by a machine frame so as to be slidable vertically parallel to the iron bar and has a presser foot at the bottom; a coil spring that is located within the machine frame and whose lower end presses the presser bar; a spring holder located within the machine frame that presses the upper end of the coil spring; and a spring holder located within the machine frame that connects the upper shaft of the sewing machine and the spring holder, and that presses the spring holder with the needle during one rotation of the upper shaft of the sewing machine. 1. A presser foot device for a sewing machine, comprising: a motion converting mechanism that reciprocates once in the vertical direction in synchronization with the vertical movement of the rod, wherein the presser rod is constantly lowered by the biasing force of the coil spring. 2. The motion conversion mechanism is comprised of an eccentric cam fixed to the upper shaft of the sewing machine, and a link mechanism that engages with the eccentric cam and drives the spring presser back and forth once in the vertical direction during one rotation of the eccentric cam. A presser foot device for a sewing machine according to claim 1. 3. The sewing machine according to claim 2, wherein the eccentric cam is fixed to the upper shaft of the sewing machine with a fixture that can adjust the correlation of the distance from the upper shaft of the sewing machine to the eccentric cam surface with respect to the rotation angle of the upper shaft of the sewing machine. presser foot device. 4. The eccentric cam has a circular cam surface; the link mechanism includes a ring-shaped cam follower having a circular hole whose inner surface is in contact with the cam surface, and a ring-shaped cam follower that is continuous with the cam follower and has a circular hole in the hole. A connecting body having a connecting arm extending in the radial direction, a driven arm having one end pivotally connected to the tip of the arm, a drive shaft rotatably supported on the machine frame and having the other end of the driven arm fixed, and the drive shaft. It has a drive arm fixed to the shaft at one end and connected to a spring retainer at the other end;
A presser foot device for a sewing machine according to claim 2. 5. The presser foot device for a sewing machine according to claim 4, wherein the drive arm is fixed to the drive shaft with a fixture that can adjust the angle formed between the drive arm and the driven arm.