JPH04332593A - Sewing machine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sewing machine in which a presser foot for pressing down sewing material is moved up and down in synchronization with the rise and fall of a needle.

0002

2. Description of the Related Art In a sewing machine that sews sewing materials such as thick cloth or leather, a sewing machine arm supports a needle bar so as to be able to move up and down, and a sewing material holding means is provided which is relatively movable across this lifting path. A presser foot is provided to prevent the sewing material held by the sewing material holding means from lifting up. With this configuration, the presser foot is lowered onto the sewing material while the needle is penetrating the sewing material in synchronization with the lifting and lowering of the needle attached to the lower end of the needle bar, and the presser foot is raised at other times. The presser foot is moved up and down at a predetermined operating stroke so as to move the presser foot up and down.

[0003] As an example of such a configuration, Japanese Unexamined Patent Application Publication No. 63
There is one described in Japanese Patent No.-11192. In this configuration, the lowermost position of the presser foot is further displaced depending on the thickness of the sewing material. This prevents the pressing pressure of the presser foot against the sewing material from increasing when the thickness of the sewing material changes during sewing (when performing so-called step stitching), especially when the sewing material becomes thick. This prevents damage to the sewing material and poor stitching quality of the thread.

0004

In the conventional structure described above, the operating stroke amount of the presser foot is fixed to a preset amount. Here, if the operating stroke amount of the presser foot is set small, it will not be possible to sew thick sewing materials such as urethane, so the operating stroke amount is set quite large so that the thickest material can be sewn. However, when the operating stroke amount of the presser foot increases, a problem arises in that vibration and noise increase. Therefore, it is desirable to make the operating stroke amount of the presser foot as small as possible.

In order to realize this, the operating stroke amount of the presser foot may be adjusted in accordance with the thickness, material, etc. of the sewing material. On the other hand, in the conventional configuration described above, the operating stroke amount of the presser foot is set according to the shape of the swinging cam, so in order to adjust the operating stroke amount, the swinging cam must be replaced. This involved extremely difficult and troublesome work. Therefore, it has been almost impossible for the user to adjust the operating stroke amount of the presser foot.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a sewing machine that can easily adjust the operating stroke amount of the presser foot while preventing damage to the sewing material and poor sewing quality of the thread. It is on offer.

[0007]

[Means for Solving the Problems] The sewing machine of the present invention includes a needle bar which is supported on a sewing machine arm so as to be movable up and down, and has a needle attached to its lower end, and a needle bar which holds sewing material and crosses the up and down path of the needle with respect to the needle. and a presser foot for preventing the sewing material held by the sewing material holding means from lifting up. In a sewing machine, the presser foot is moved up and down with a predetermined operating stroke so that the presser foot is lowered onto the sewing material while the sewing material is being penetrated, and the presser foot is raised during other times, The sewing machine is characterized in that it includes a lowest position switching means for displacing the lowest position of the presser foot according to the thickness of the sewing material, and a stroke amount adjusting means for adjusting the operating stroke amount of the presser foot. It is.

[0008]

[Operation] According to the above means, since the lowest position switching means displaces the lowest position of the presser foot according to the thickness of the sewing material, the presser foot presses down the sewing material when the thickness of the sewing material changes. It is possible to prevent the pressure from increasing. Therefore, it is possible to prevent the sewing material from being damaged and the stitching quality of the thread becoming poor. Further, since the stroke amount adjusting means is configured to adjust the operating stroke amount of the presser foot, the operating stroke amount of the presser foot can be easily adjusted in accordance with the thickness, material, etc. of the sewing material.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. 1 to 3. First, Figures 1 and 2
A sewing machine main body is composed of a sewing machine arm 1 and a sewing machine bed (not shown). A sewing machine head 2 is provided on the left side of the sewing machine arm 1, and an opening 2a is formed in the left end surface of the sewing machine head 2. On the left end surface of the sewing machine head 2, a face plate (not shown) is attached to the opening 2.
A is pivoted to open and close.

A needle bar 3 is provided within the sewing machine head 2 so as to be movable up and down, and its lower end protrudes downward from the sewing machine head 2. A needle 4 is attached to the lower end of the needle bar 3. The needle bar 3 is reciprocated up and down by a sewing machine motor 35 (see FIG. 3) via a main shaft 5 and a crank mechanism (not shown).

A presser foot bar 6 is arranged parallel to the rear of the needle bar 3 and is movable up and down. A cloth presser foot 7 for pressing down the sewing material is attached to the lower end of the cloth presser rod 6. A presser foot 7a is provided at the lower end of the presser foot 7, and a through hole 7b is provided in the presser foot 7a.
are formed to be oriented in the vertical direction. This through hole 7b
The needle 4 is inserted inside. In addition, the presser foot bar 6 is
Guide rail 8 with a U-shaped cross section fixed inside the sewing machine head 2
is housed within.

A coil spring 10 is provided between the upper end of the presser foot bar 6 and a presser foot pressure adjusting screw 9 provided at the top of the sewing machine head 2. The coil spring 10 urges the presser rod 6, that is, the presser foot 7 downward. The presser foot rod 6 is reciprocated up and down by the sewing machine motor 35 via the main shaft 5 and the driving force transmission mechanism 11.
As a result, the needle 4 is driven to reciprocate up and down in synchronization with the movement of the needle 4. The driving force transmission mechanism 11 will be explained below.

An eccentric wheel 12 is attached to the main shaft 5, and one end of a rod 13 is rotatably connected to the eccentric wheel 12. The other end of the rod 13 is rotatably connected to an adjustment arm 14. The upper end of the adjustment arm 14 is fixed to the rotation shaft 15, and is configured to rotate together with the rotation shaft 15. The adjustment arm 14 has an elongated groove 14.
a is formed, and a screw 16 is inserted into this groove 14a and is tightened and fixed with a nut (not shown). This screw 16 is adjustable so that it can be fixed at any position within the groove 14a.

The other end of the rod 13 mentioned above is
It is rotatably connected to the screw 16. by this,
By changing the fixing position of the screw 16, the rod 13
The connecting position between the adjusting arm 14 and the adjusting arm 14 can be adjusted. In this case, the rod 13, the adjustment arm 14, the groove 14a
, screw 16, etc. constitute a stroke amount adjusting means 17. As shown in FIG. 2, the stroke amount adjusting means 17 is provided at the outer rear part of the sewing machine head 2 so as to protrude rearward and be exposed.

Further, the upper end of a first connecting rod 18 is fixed to the left end side of the rotating shaft 15, so that the first connecting rod 18 rotates together with the rotating shaft 15. ing. A left end portion of a second connecting rod 19 in FIG. 1 is rotatably connected to the lower end portion of the first connecting rod 18 . The right end of the second connecting rod 19 in FIG.
0 (in this case, the top located at the top) via a pin 21 so as to be rotatable.

The intermediate portion of the presser foot bar 6 described above is rotatably connected to the second apex portion (in this case, the apex portion located at the intermediate portion) of the triangular link 20 via a pin 22 . The pin 23 protruding from the third vertex of the triangular link 20 (in this case, the lower vertex)
It is fitted into a long hole 24a formed on the middle right end side. This lever 24 is rotatably supported by a shaft 25, and its left end side in FIG. 2 projects rearward from the rear of the sewing machine head 2.

At the upper left end of the lever 24 in FIG.
4b is formed, and the eccentric cam 2 is attached to this contact portion 24b.
The cam surfaces 26a of No. 6 come into contact with each other. In this case, the lever 24 is biased clockwise in FIG. 2 by a spring (not shown). The eccentric cam 26 is provided at the lower end of a shaft 27, and is rotatably driven by a presser foot displacement motor 28 via this shaft 27.

The presser foot displacement motor 28 is composed of, for example, a pulse motor. Presser foot displacement motor 2
8 is arranged at the rear of the outer upper part of the sewing machine head 2. When the eccentric cam 26 rotates, the lever 24 rotates about the shaft 25, and the position of the third apex of the triangular link 20, that is, the pin 23, is displaced in the vertical direction. The lever 24, the eccentric cam 26, the presser foot displacement motor 28, and the like constitute a lowest position switching means 29.

Further, in FIG. 3 showing the electrical configuration, the CPU 30, which is a control means for controlling the entire sewing operation, is connected to the R
The control program and the like stored in the OM 31 are inputted, as well as the sewing data stored in the RAM 32. For example, when sewing cloth as a sewing material, the sewing data includes data indicating changes in the thickness of the cloth as sewing progresses. Further, switch signals output from various switches provided on the operation panel 33 are provided to the CPU 30 via an interface circuit 34.

[0020]The CPU 30 also controls the sewing machine motor 35.
, the X-direction movement motor 36, the Y-direction movement motor 37, or the presser foot displacement motor 28 are driven and controlled via respective drive circuits 38-41. Note that an interface circuit 4 is provided between the CPU 30 and the drive circuits 38 to 41.
2 is provided. Further, the cloth held by the sewing material holding means (not shown) is fed and moved in the X direction by driving the X direction movement motor 36, and is fed in the Y direction by driving the Y direction movement motor 37. It is about to be moved.

Next, the operation of the above configuration will be explained. For example, when sewing thick cloth, the sewing machine motor 35 is driven and the main shaft 5
By rotating the needle bar 3, that is, the needle 4, to raise and lower it,
Sew the above cloth. At this time, the cloth presser bar 6 is moved up and down by the rotation of the main shaft 5 via the driving force transmission mechanism 11, so that the cloth presser foot 7 is driven in synchronization with the raising and lowering of the needle 4. Specifically, the presser foot 7 is controlled to descend onto the cloth while the needle 4 is penetrating the cloth, and to rise during the rest of the time. The operation of the driving force transmission mechanism 11 will be described below.

First, as shown in FIG. 1, when the main shaft 5 rotates, the eccentric wheel 12 rotates and the rod 13 swings in the direction of arrow A. This swinging of the rod 13 causes the adjustment arm 14 to swing in the direction of arrow B, the first rod 18 to swing in the direction of arrow C, and the second rod 19 to swing in the direction of arrow D. Here, the contact portion 24b of the lever 24 is connected to the eccentric cam 2.
6, the position of the lever 24 is fixed. As a result, in the triangular link 20, the pin 21, which is the first apex portion, swings in conjunction with the swinging of the second rod 19, and the pin 23, which is the third apex portion, moves through the elongated hole 24a of the lever 24. The pin 22, which is the second apex portion, moves up and down.

As a result, the presser foot 6 is moved up and down, that is, the presser foot 7 is moved up and down. Here, the operating stroke amount of the presser foot 7, that is, the presser rod 6, is determined by the amount of rocking of the triangular link 20, that is, the amount of reciprocating rotation of the adjusting arm 14. That is, by changing the fixing position of the screw 16 of the stroke amount adjusting means 17 and adjusting the connection position between the rod 13 and the adjusting arm 14, the amount of reciprocating rotation of the adjusting arm 14, that is, the operating stroke amount of the presser foot 7 can be adjusted. Can be adjusted.

Further, the lowest position of the presser foot 7 is located at the lowermost position of the presser foot 7.
The lowest position of the operating stroke is determined by the rotational position of the lever 24 when the operating stroke amount is fixed. That is, when the lever 24 rotates, the elongated hole 2
Since the position of 4a moves up and down, the entire sliding trajectory of the pin 23 of the triangular link 20 moves up and down, and the lowest and highest positions of the pin 22 of the triangular link 20 move up and down. In other words, the pin 22 of the triangular link 20 and the entire operating range of the operating stroke of the presser rod 6 are configured to move up and down.

Now, when the thickness of the cloth changes, the lowest position of the presser foot 7 is moved in accordance with the thickness of the cloth. in this case,
The lever 24 is rotated by energizing and driving the displacement motor 28 of the lowest position switching means 29 based on the cloth thickness data stored in the RAM 32. That is, the displacement motor 28 is energized and driven to rotate the eccentric cam 26 to change the contact position between the cam surface 26a and the contact portion 24b of the lever 24.

By changing this contact position, the rotational position of the lever 24 changes as described above, and the entire operating range of the operating stroke of the presser rod 6 moves up and down. Therefore, the lowest position of the presser foot 7 can be displaced in the vertical direction depending on the thickness of the cloth. As a result, when the thickness of the cloth changes, the pressure of the cloth presser foot 7 that presses down the cloth can be prevented from increasing. Therefore, it is possible to prevent the cloth from being damaged and the stitching quality of the thread becoming poor.

Furthermore, since the stroke amount adjusting means 17 is configured to adjust the operating stroke amount of the presser foot 7, the operating stroke amount of the presser foot 7 can be easily adjusted in accordance with the thickness and material of the cloth. Can be done. In particular, when sewing a sewing material such as urethane with high cushioning properties, adjusting the operating stroke amount of the presser foot 7 can prevent damage to the sewing material and poor sewing quality of the thread.

To be more specific, sewing materials such as urethane with high cushioning properties must be sewn while being pressed with a certain degree of force by the presser foot 7. On the other hand, in order to prevent the presser foot 7 from getting caught on the sewing material when the sewing material is fed, since the sewing material such as urethane is thick, the lowermost position of the presser foot 7, that is, the uppermost position, must be moved upward. Must be set.

Therefore, when sewing a sewing material such as urethane, the lowest position switching means 29 sets the lowest and highest positions of the presser foot 7 upward, and the stroke amount adjusting means 17 adjusts the operation of the presser foot 7. Increase the stroke amount. As a result, it is possible to prevent the presser foot 7 from getting caught on the sewing material, and it is also possible to sew the sewing material while being pressed with a certain degree of force by the presser foot 7.

On the other hand, when sewing thin sewing materials or sewing materials with low cushioning properties, the stroke amount adjusting means 1
If the operating stroke amount of the presser foot 7 is reduced by 7,
Mechanical vibration can be minimized and noise can be reduced.

FIG. 4 shows a second embodiment of the present invention, in which the same parts as in the first embodiment are given the same reference numerals, and different parts will be explained. In FIG. 4, the cloth thickness detector 43 is
It is composed of a light emitting element, a light receiving element, etc., and is configured to automatically detect the thickness of the sewing material and provide the detected signal to the CPU 30 via the interface circuit 34. Therefore, in this second embodiment, almost the same effects as in the first embodiment can be obtained, but in particular, the thickness of the sewing material can be automatically detected by the cloth thickness detector 43. Therefore, it is possible to eliminate the need for inputting data on the thickness of sewing material and storing it in the RAM 32.

[0032]

Effects of the Invention As is clear from the above description, the present invention has a structure in which the lowest position switching means displaces the lowest position of the presser foot according to the thickness of the sewing material, so that the thickness of the sewing material changes. When doing so, the pressure of the presser foot that presses down the sewing material can be prevented from increasing, and the sewing material can be prevented from being damaged and the stitching quality of the thread can be prevented from becoming poor. Also,
Since the operating stroke amount of the presser foot is adjusted by the stroke amount adjusting means, the operating stroke amount of the presser foot can be easily adjusted according to the thickness and material of the sewing material, thereby reducing mechanical vibration. It can be made as small as possible and has excellent effects, particularly when sewing materials with high cushioning properties.

[Brief explanation of drawings]

FIG. 1 is a perspective view of the vicinity of a driving force transmission mechanism of a presser foot showing a first embodiment of the present invention.

[Figure 2] Side view of the area around the drive force transmission mechanism of the presser foot

[Figure 3]
Block Diagram

FIG. 4 is a diagram corresponding to FIG. 3 showing a second embodiment of the present invention.

[Explanation of symbols]

1 is a sewing machine arm, 3 is a needle bar, 4 is a needle, 5 is a main shaft, 7 is a presser foot, 11 is a driving force transmission mechanism, 17 is a stroke amount adjusting means, 24 is a lever, and 29 is a lowest position switching means. .

Claims (1)

[Claims] [Claim 1] Supported on a sewing machine arm so as to be movable up and down,
and a needle bar having a needle attached to its lower end, a sewing material holding means that holds sewing material and is moved relative to the needle across an elevation path thereof, and lifting of the sewing material held by the sewing material holding means. and a presser foot for preventing the needle from moving upwardly and downwardly, and lowering the presser foot onto the sewing material while the needle is penetrating the sewing material in synchronization with the raising and lowering of the needle;
In a sewing machine in which the presser foot is moved up and down at a predetermined operating stroke so as to raise the presser foot during other times, the lowest position of the presser foot is displaced according to the thickness of the sewing material. A sewing machine comprising: a lowermost position switching means; and a stroke amount adjusting means for adjusting an operating stroke amount of the presser foot.