JPH04329997A - Needle bar device of sewing machine - Google Patents

Abstract

PURPOSE:To prevent noises generated when a cloth press abuts against a stopper, in a needle device of a sewing machine in which the cloth press moves vertically together with the needle bar and stopped at a certain position by a stopper. CONSTITUTION:A vibration absorber 34 is fitted to a connection piece jointing the upper and lower supporting pieces 26, 27 in a cloth press 24. A spring to interlock a needle 7 with the cloth press 24 brings about the natural oscillation by the shock of abutment of the cloth press 24 against a stopper 38. But, if the oscillation is conducted to the upper supporting pieces 26, 27, the conduction of oscillation to the lower supporting pieces 26, 27 through a connection rod 28 is prevented by the vibration absorber 34. As a result, the oscillation of the cloth press 24 is decreased and the noises due to the oscillation are suppressed.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a needle bar device for a sewing machine, and more particularly to a needle bar device for a sewing machine equipped with a presser foot that moves up and down in conjunction with the needle bar.

0002

2. Description of the Related Art A needle bar device of this type is constructed as shown in FIG. 11, for example. In FIG. 11, 6h is a base frame, 7h is a vertically movable needle bar, 24h is a presser foot, which has upper and lower support pieces 26h, 27h, and needle bars 7h are inserted into through holes 35h, 36h drilled in these. is inserted through it so that it can move up and down. 41h is a first spring for urging the support piece 26h upward against the base frame 6h, 45h is a second spring for urging the support piece 26h downward against the needle bar 7h, 38
h is a stopper for stopping the lowering of the support piece 26h at a certain position.

[0003] In such a needle bar device, the needle bar 7h
When the presser foot 24h is lowered via the second spring 45h,
is lowered, and then when the needle bar 7h is raised, the first spring 4
1h, the presser foot 24h is raised to its original position. That is, the presser foot 24h moves up and down in conjunction with the needle bar 7h, and proper sewing can be performed while pressing the cloth 50h against the throat plate 9h with the presser foot 24h. Also, when the presser foot is lowered as described above, the support piece 26h is moved to the stopper 38h.
By coming into contact with the presser foot 24h, the lowering of the presser foot 24h is stopped at a certain position, and as a result, sewing can be performed without pressing down the fabric excessively.

0004

[Problems to be Solved by the Invention] However, in this type of needle bar device, the above-mentioned through holes 35h and 36h are connected to the needle bar 7h in order to smooth the relative vertical movement between the needle bar 7h and the presser foot 24h.
Since the diameter of the presser foot 24h is larger than the diameter of the needle bar 7h and there is a gap between the needle bar 7h and the needle bar 7h, the presser foot 24h vibrates when the support piece 26h hits the stopper 38h.
There was a problem in that noise was generated between the needle bar 7h and the through hole 36h. Moreover, since contact with the stopper 38h occurs every time one stitch is sewn, there is a problem in that when hundreds of stitches are sewn per minute, the noise becomes extremely loud. In order to prevent the above-mentioned noise, it has been devised to provide a noise-reducing cylinder inside the above-mentioned through hole 36h where the noise is generated, but since the cylinder constantly rubs against the needle bar 7h, There is a problem in that it wears out quickly, causing noise to be generated again.

The present invention has been made in order to solve the problems (technical problems) of the prior art described above, in which the presser foot moves up and down in conjunction with the vertical movement of the needle bar, and a stopper prevents the lowering of the presser foot. An object of the present invention is to provide a needle bar device for a sewing machine, which suppresses the vibration of the presser foot to prevent the generation of noise and enables quiet operation even when the presser foot is stopped at a fixed position. It is said that

[0006]

[Means for Solving the Problems] In order to achieve the above object, the needle bar device of the sewing machine according to the present invention has a needle bar mounted so as to be movable up and down with respect to the base frame, and a presser foot that is attached to the needle bar so as to be movable up and down relative to the base frame. The presser foot is made up of a support and a presser piece attached to the lower part of the presser foot. The structure of attaching the presser foot to the needle bar is such that when each of the support pieces is positioned above and below the base frame, The needle bar passes through the through hole in the support piece so as to be able to move up and down, and the needle bar is provided between the base frame and the upper support piece of the presser foot in order to bias the support piece upward. A first spring is interposed between the needle bar and the upper support piece, and a second spring is interposed between the needle bar and the upper support piece for biasing the support piece downward with respect to the needle bar. In the needle bar device of the sewing machine, the base frame is further provided with a stopper for stopping the lowering of the upper support piece of the presser foot at a certain position. .

[0007]

[Operation] When the needle bar is lowered, the presser foot is lowered via the second spring. The lowering of the presser foot is stopped when the upper support piece comes into contact with the stopper. During the above contact, the spring for interlocking the needle bar and presser foot generates natural vibration due to the impact of the contact, and even if this is transmitted to the upper support piece, the vibration is transferred to the lower support piece through the connecting rod. Vibration suppression means prevents the vibration from being transmitted to the piece. As a result, the vibration of the presser foot becomes slight, and the generation of noise accompanying the vibration is suppressed.

[0008]

Embodiments The drawings showing embodiments of the present application will be described below. FIG. 1 shows a part of a sewing machine head in a multi-needle sewing machine. 1 is the base frame of the sewing machine head, and the main body 1a
and a needle bar holding frame 1b which is horizontally rotatably attached to the main body 1a. In the case of a single needle sewing machine, both are integrally constructed. Reference numeral 2 denotes a lifting rod attached to the main body 1a so that it can move up and down; 3, a main shaft rotated by a motor not shown; and 4, a lifting mechanism in which the lifting rod 2 is moved up and down by rotation of the main shaft 3. As an example, a well-known crank mechanism is used, in which 15 is a rotating body attached to the main shaft 3, 16 is a stop fixed to the lifting rod 2, 17 is a coupling member attached to the lifting rod 2 so as to be relatively rotatable, 18 is a crank rod. 5
is a needle bar presser attached to the lifting rod 2. Reference numeral 6 indicates a needle bar device mounted on the holding frame 1b. Reference numeral 9 denotes a well-known needle plate provided on the bed of the sewing machine, and is provided with a needle hole 9a.

Next, the needle bar device 6 will be explained. Reference numeral 7 denotes a needle bar, which is made of carbon steel for mechanical structures, such as S45C, and has an outer diameter of 6.36 mm, and is inserted into a through hole (for example, inner diameter 6.38 mm) formed in the holding frame 1b in parallel with the lifting rod 2. It is also mounted so that it can move up and down. A sewing needle 8 is attached to a needle stop 7a attached to its lower end. Needle bar 7
A plurality of rods are arranged on one circumference around the rotation center of the holding frame 1b. When the holding frame 1b is rotated by a needle bar switching mechanism (not shown), the plurality of needle bars 7 are alternately positioned at sewing positions above the needle holes 9a. 21 is a receiving piece attached to the upper end of the needle bar 7, 22 is a pulling piece, and 23 is an engaging piece for preventing rotation, which has a recess 23a as shown in FIG. 2(A). Both the pulling piece 22 and the engaging piece 23 are made of stainless steel (SUS304), for example.

Next, reference numeral 24 indicates a cloth presser which is attached to the needle bar 7 so that it can move freely up and down relative to it. Reference numeral 25 denotes a support body for the presser foot 24, which is composed of upper and lower support pieces 26, 27 and a connecting rod 28 that connects them. The lower end of the connecting rod 28 is welded to the support piece 27, and the upper end is inserted into and removed from a through hole 29 formed in the support piece 26, and is fixed with a set screw 30. 31 is a presser piece attached to the lower part of the support body 25, and the support piece 2
7, and the lower end serves as a cloth presser part 32. Reference numeral 33 denotes a detent piece formed integrally with the connecting rod 28. Reference numeral 34 denotes a small diameter portion exemplified as a vibration suppressing means attached to the connecting rod 28, and the diameter thereof is, for example, 3 mm. This is formed by providing a groove around the connecting rod 28. The material of the support piece 26 is, for example, carbon steel for mechanical structure (S4
5C). The connecting rod 28 is made of stainless steel (SUS), for example.
304) and has a diameter of 3.96 mm. Support piece 27
The holding piece 31 is made of the same material as the connecting rod 28, and has a thickness of, for example, 1.91 mm.

Next, the relationship between the presser foot 24, the needle bar 7, and the holding frame 1b will be explained. 35 is a through hole drilled in the support piece 26, 36 is a through hole bored in the support piece 27,
Both are formed slightly larger than the diameter of the needle bar 7 (for example, the former is 6.38 mm and the latter is 6.40 mm), and the needle bar 7 is inserted therethrough so as to be able to freely move up and down relative to each other. Connecting rod 2
8 is vertically movably positioned in a guide groove 37 (width: 4.07 mm, for example) formed in the holding frame 1b, as shown in FIG. 2C. Further, as shown in FIG. 2A, the stopper piece 33 is positioned so as to be vertically movable relative to the recess 23a of the engaging piece 23. Next, a stopper 38 is provided on the holding frame 1b and is formed into a cylindrical shape surrounding the needle bar 7. 41 is a first spring provided around the needle bar 7;
This is for urging the support piece 26 upward against the holding frame 1b, and a compression coil spring is used, the lower end of which is brought into contact with the holding frame 1b on the outer circumferential side of the stopper 38. , the upper end portion is brought into contact with the support piece 26 on the outer peripheral side of a boss portion 42 provided on the support piece 26 . 4
Reference numeral 5 designates a second spring disposed around the needle bar 7, which urges the support piece 26 downward with respect to the needle bar 7. A compression coil spring is used, and the second spring 5 is provided around the needle bar 7. It is interposed between the support piece 26 and the supporting piece 26. As this second spring 45, one having a stronger spring force than the first spring 41 is used. Next 46
, 47, and 48 are all buffer bodies provided around the needle bar 7,
Each uses an O-ring made of an elastic material such as urethane rubber or natural rubber.

Next, the operation of the sewing machine having the above structure will be explained. As the main shaft 3 rotates, the lifting rod 2 moves up and down via the lifting mechanism 4, and the needle bar presser 5 moves up and down. When the needle bar presser foot 5 is lowered from the raised position shown in FIG. 1 to the position shown in FIG.
Push the receiving piece 21 downward and the needle bar 7 will descend as shown. As the needle bar 7 descends, the support piece 26 of the presser foot 24 is pushed down via the second spring 45, and the first spring 41 is compressed. The first spring 41 is compressed and the support piece 26
When the boss portion 42 comes into contact with the stopper 38 via the buffer 46, the downward movement of the presser foot 24 is stopped. In this state, the presser foot 32 of the cloth presser foot 24 presses the cloth 50 on the throat plate 9 with appropriate pressure. When the needle bar presser foot 5 continues to descend, the needle bar 7 also descends further, and the needle 8 moves toward the fabric 5.
0 and the needle hole 9a to reach the lower part. In this state, the upper thread and lower thread are entwined under the throat plate 9 in a well-known manner. Thereafter, as the needle bar presser foot 5 rises, the needle bar 7 is moved to the second spring 4.
It rises with the urging force of 5. In the process, the needle bar 7
After being raised to the position shown in , the presser foot 24 is raised to its original position by the urging force applied to the support piece 26 from the first spring 41 as the needle bar 7 is raised. Such operations are repeated one after another, and sewing on the cloth 50 is performed continuously.

During sewing as described above, when the boss portion 42 of the lowered support piece 26 contacts the stopper 38 via the buffer 46 as shown in FIG. 3, the impact causes the first spring 4 to
The first and second springs 45 or the buffer 46 may generate natural vibrations. However, even if they generate natural vibrations and the vibrations are transmitted to the support piece 26 and further to the connecting rod 28,
In the connecting rod 28, from the support piece 26 to the support piece 27
The way the vibration is transmitted to the location is changed by the small diameter portion 34 in the middle. As a result, vibrations are hardly transmitted to the connecting piece 28 as a whole, the vibration of the supporting piece 27 is extremely weak, and the generation of noise between it and the needle bar 7 is extremely weak. Furthermore, the fact that vibrations are less likely to be transmitted as described above means that the vibration of the presser foot 24 as a whole is also reduced, and the generation of noise from between the support piece 26 and the needle bar 7 is also reduced.

In the sewing machine having the above configuration, the presser foot 24
The distance between the support piece 26 and the presser part 32 can be adjusted. That is, loosen the set screw 30 and attach the connecting rod 28 to the support piece 26.
The above-mentioned interval can be adjusted by repositioning up and down. Therefore, when the lowering of the support piece 26 is stopped by the stopper 38, the position of the presser part 32 can be set higher than the position shown in FIG. 3. When sewing is performed in such a state, the fluffy cloth can be sewn without being crushed by the presser foot.

Next, the dimensions L1 to L5 of each part shown in FIG.
An example is as follows. L1=41mm, L2
=20mm, L3=5mm, L4=58mm, L5=1
It is 0mm. The narrow diameter portion 34 may be provided at any other position as long as it does not interfere with the support piece 26 or the guide groove 37.

Next, different embodiments will be explained. Figure 4
In the example shown in , various grooves are provided around the connecting rod 28 as vibration suppressing means. Among these, (A) is an example in which only one V-shaped groove 55 is formed, (B) is an example in which only one U-shaped groove 56 is formed, and (C) is an example in which a plurality of U-shaped (or V-shaped) grooves 57 are formed. For example, (D) is an example in which a plurality of U-shaped (or V-shaped) grooves 58 are formed at multiple locations, and (E) is an example in which knurled grooves 59 are formed. It should be noted that the same reference numerals as in the previous figure are given to parts that are functionally the same or equivalent to those in the previous figure, and redundant explanations are omitted. (In addition, the same concept is used in the following figures, and the same reference numerals are used to omit duplicate explanations.)

Next, FIG. 5 shows a connecting rod 28 as a vibration suppressing means.
This is an example of forming a small hole in the. (A) is an example in which one small hole 61 is formed, and the cross-sectional shape at the BB location is as shown in (B). The diameter of the small hole 61 is, for example, 1.5 mm, and the dimensions of each part are 41 mm for L6, 22 mm for L7, and 61 mm for L8. In this example, the connecting rod 28 may be a flat plate. (C) is an example in which the above-mentioned small holes 61 are bored in various places at irregular intervals (equal intervals may be used), and (D) is an example in which they are formed alternately vertically and horizontally at equal intervals (unequal intervals are also acceptable). be.

Next, FIG. 6 shows a connecting rod 28 as a vibration suppressing means.
This is an example in which a foreign member is attached in the middle of the . (A) is an example in which an elastic body 62 (for example, rubber) is provided around the periphery, and the cross-sectional shape at the BB location is as shown in (B). The thickness of the elastic body 62 is, for example, 1 mm, and the dimensions of each part are L9 of 41 mm,
L10 is 15 mm, L11 is 15 mm, and L12 is 53 mm. (C) is a small diameter part 34 like the example in FIG.
This is an example in which an elastic body 62 is provided around the periphery. The dimensions of each part are L
13 is 41mm, L14 is 10mm, L15 is 1
5mm, and L16 is 58mm.

Next, FIG. 7 shows a connecting rod 28 as a vibration suppressing means.
This is an example in which vertical grooves are formed on the surface. (A) is an example in which a vertically straight groove 64 is formed in the connecting rod 28, and the cross-sectional shape at the line B-B is as shown in (B). Such a groove 64
3 may be formed. (C) is an example in which a groove 65 is formed in a spiral shape on the connecting rod 28.

Next, FIG. 8 shows a connecting rod 2 as a vibration suppressing means.
This is an example in which the rotation preventing piece 33 attached to the connecting rod 8 is formed to have a smaller diameter than the connecting rod 28.

Next, FIG. 9(A) shows vibration suppressing means.
This is an example in which the connecting rod 28 is formed of a hollow pipe and the hollow portion 66 is filled with a sound deadening material 67, and the cross-sectional shape at the B-B location is as shown in (B). As the sound deadening material 67, a urethane-based material (specifically, polyethylene) is used. The filling method is to plug one end 68 of the hollow pipe, and inject the sound deadening material in a liquid state from the other end and solidify it.

FIG. 9(C) is an example in which a part of the entire length of the connecting rod 28 is hollowed out as a vibration suppressing means, and the cross-sectional shape at the D-D location is as shown in FIG. 9(D). 69 indicates a hollow part.

Next, FIG. 10 shows a connecting rod 2 as a vibration suppressing means.
This is an example in which a large-diameter portion 70 is formed in a part of 8.

[0024]

[Effect of the invention] As described above, in the present invention, the first
Because of the presence of the spring 41 and the second spring 45, when sewing is performed by moving the needle bar 7 up and down, the presser foot 24 moves up and down in conjunction with the movement, and can press the cloth each time, allowing for proper sewing. Of course,

When the presser foot 24 is lowered during the sewing described above, the support piece 26 of the presser foot 24 touches the stopper 3.
8 and stops the lowering of the presser foot 24 at a certain position, which also has the advantage of preventing excessive pressing of the cloth.

Moreover, since the support piece 26 comes into contact with the stopper 38 as described above, the interlocking springs 41 and 45 generate natural vibrations due to the impact caused by the contact, and this vibration causes the support of the presser foot 24 to Even if the vibration is transmitted to the piece 26, the presser foot 24 has the advantage that the presence of the vibration suppressing means in the connecting rod 28 makes it difficult for the vibration to be transmitted. This means that even if the through hole 36 of the support piece 27 is formed large enough to allow relative vertical movement between the support piece 27 and the needle bar 7, the vibration of the presser foot 24 can be suppressed. This has the effect of preventing large noises from being generated due to repeated collisions between the inner circumferential surface of the through hole 36 of the support piece 27 and the outer circumferential surface of the needle bar 7.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway side view of a sewing machine head.

[Fig. 2] (A) is an enlarged sectional view taken along line AA in Fig. 1;
) is an enlarged sectional view taken along line BB in FIG. 1, and (C) is an enlarged sectional view taken along line CC in FIG.

FIG. 3 is a partial vertical cross-sectional view showing a state in which the support piece of the presser foot has been lowered to a position where it contacts a stopper.

FIGS. 4A to 4E are partial views showing examples of different shapes of vibration suppressing means, respectively.

FIGS. 5A to 5D are diagrams showing examples in which small holes are formed in the connecting rod.

FIGS. 6A to 6C are views showing an example in which an elastic body is attached to a connecting rod.

FIGS. 7A to 7C are diagrams showing an example in which a vertical groove is formed in a connecting rod.

FIG. 8 is a diagram showing an example in which the stopper piece is formed to have a small diameter.

FIGS. 9A and 9B are views showing an example in which a connecting rod is filled with a sound deadening material, and FIGS. 9C and 9D are views showing an example in which a part of the connecting rod is hollow.

FIG. 10 is a diagram showing an example in which a large diameter portion is formed in a part of the connecting rod.

FIG. 11 is a longitudinal sectional view showing a needle bar device in a conventional sewing machine.

[Explanation of symbols]

7 Needle bar 24 Presser foot 26, 27 Support piece 28 Connecting rod 34 Vibration suppression means 38 Stopper 41 First spring 45 Second spring

Claims (1)

[Claims] [Claim 1] A cloth presser is attached to a needle bar which is attached to a base frame so as to be able to move up and down relative to the base frame, and the presser foot is attached to a support and its lower part. The support body consists of upper and lower support pieces each having a through hole with a diameter larger than that of the needle bar, and a connecting rod that connects them. The attached structure is such that when the support pieces are positioned above and below the base frame, the needle bar passes through the through holes in the support pieces so as to be able to move up and down. A first spring for urging the support piece upward is interposed between the base frame and the upper support piece of the presser foot, and a first spring is interposed between the base frame and the upper support piece of the presser foot. A second spring is interposed between the needle bar and the base frame to bias the support piece downward against the needle bar. What is claimed is: 1. A needle bar device for a sewing machine, which is equipped with a stopper for receiving the needle in position, wherein a vibration suppressing means is attached to a connecting rod of the presser foot.