CN109183288B - Cloth pressing device of sewing machine and sewing machine - Google Patents

Abstract

The invention provides a cloth pressing device of a sewing machine, which comprises a machine shell, a fixed sleeve fixed on the machine shell, an ejector rod arranged on the machine shell and positioned above the fixed sleeve, a presser bar sleeved in the fixed sleeve in a vertically movable mode, a presser foot arranged at the lower end of the presser bar, a check ring arranged on the periphery of the presser bar, a first spring and a second spring sleeved on the presser bar, wherein the upper end and the lower end of the first spring are respectively abutted against the ejector rod and the presser bar, the upper end and the lower end of the second spring are respectively abutted against the fixed sleeve and the check ring, and the elastic modulus of the second spring is greater than that of the first spring. In this application, when the cloth thickness of presser foot below increases, the cloth of thickening makes the presser foot shift up, and then the drive presser bar shifts up, compresses the second spring, and the trace compression of second spring can make presser foot pressure show and increase to make the cloth presser device to the pressure that the cloth was applyed can be along with the increase of cloth thickness and increase fast, the jump needle that produces when solving the thick material, defects such as gauge change density, the reliability is high.

Description

Cloth pressing device of sewing machine and sewing machine

Technical Field

The invention relates to a sewing machine, in particular to a cloth pressing device of the sewing machine.

Background

At present, a cloth pressing device in a sewing machine on the market is generally a presser foot mechanism, the presser foot mechanism mainly comprises a presser foot rod and a presser foot arranged at the lower end of the presser foot rod, and the presser foot is matched with a cloth feeding tooth in the sewing machine to realize backward transfer of cloth in the sewing process. However, the conventional presser foot mechanism generally has the following problems: when the sewn cloth is thickened suddenly, the pressure of the presser foot mechanism cannot be increased rapidly along with the increase of the thickness of the cloth; when the sewn cloth becomes thin suddenly, the presser foot in the presser foot mechanism is easy to be in a suspended state. Therefore, when the sewn cloth is suddenly thickened and thinned, the conventional presser foot mechanism is easy to generate phenomena of blockage, stitch skipping, density change of stitch pitch and the like, so that the conventional presser foot mechanism has certain limitation.

Disclosure of Invention

In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide a cloth pressing device of a sewing machine, which can rapidly increase the pressure applied to the cloth with the increase of the thickness of the cloth.

In order to achieve the purpose, the invention provides a cloth pressing device of a sewing machine, which comprises a machine shell, a fixed sleeve fixed on the machine shell, a push rod arranged on the machine shell and positioned above the fixed sleeve, a presser bar sleeved in the fixed sleeve in a vertically movable mode, a presser foot arranged at the lower end of the presser bar, a check ring arranged on the periphery of the presser bar, a first spring and a second spring sleeved on the presser bar, wherein the upper end and the lower end of the first spring are respectively abutted against the push rod and the presser bar, the upper end and the lower end of the second spring are respectively abutted against the fixed sleeve and the check ring, and the elastic modulus of the second spring is larger than that of the first spring.

Furthermore, the cloth pressing device of the sewing machine also comprises a lever, a first driving block, a sleeve, a piston, an installation inner cavity, a third spring and a second driving block, wherein the lever extends forwards and backwards along the cloth feeding direction of the sewing machine for feeding cloth backwards, the first driving block is installed at the rear end of the lever, the sleeve is fixed at the front end of the lever, the piston is sleeved in the sleeve in a manner that the upper section of the piston can move up and down, the installation inner cavity is formed by the sleeve and the piston, the third spring is arranged in the installation inner cavity, the second driving block is installed at the lower end of the piston, the presser foot is hinged to the presser foot rod, the upper end and the lower end of the third spring are respectively abutted against the; as the thickness of the cloth increased, (F1+ F2) resistance arm > F3 power arm; when the thickness of the cloth is reduced, (F1+ F2) resistance arm < F3 power arm, the front end of the presser foot is rotated downwards; the F1 is the force applied by the first spring to the presser foot, the F2 is the force applied by the second spring to the presser foot, and the F3 is the force applied by the third spring to the presser foot.

Furthermore, the first driving block is a roller and can be rotatably arranged at the rear end of the lever, and the second driving block is a roller and can be rotatably arranged at the lower end of the piston.

Further, the presser foot includes a horizontally extending presser foot main body portion, a cloth guide portion extending obliquely forward and upward from a front end of the presser foot main body portion, and a spring holding portion extending obliquely rearward and upward from an upper end of the cloth guide portion, and the second driving block abuts against an upper end surface of the spring holding portion.

Further, the presser foot is a unitary piece.

Furthermore, the cloth pressing device of the sewing machine further comprises a supporting plate, the upper end of the supporting plate is fixed on the machine shell, the lower end of the supporting plate is hinged to the lever, and a hinged point of the supporting plate and the lever forms a fulcrum of the lever.

Furthermore, the supporting plate is installed on the casing through a first fixing screw, a mounting groove extending along the length direction of the supporting plate is formed in the upper end of the supporting plate, the first fixing screw penetrates through the mounting groove, and the mounting position of the supporting plate on the casing is adjustable in the extending direction of the mounting groove.

Furthermore, the elastic modulus of the second spring is 3-10 times of that of the first spring.

Further, the ejector rod is in threaded connection with the machine shell, and the installation position of the ejector rod on the machine shell is adjustable in the vertical direction.

Furthermore, the check ring is fixed on the presser foot rod through a second fixing screw, and the installation position of the check ring on the presser foot rod is adjustable in the up-down direction.

The invention also provides a sewing machine, wherein the cloth pressing device is arranged in the sewing machine.

As described above, the cloth pressing device of the sewing machine and the sewing machine according to the present invention have the following advantageous effects:

in this application, when the cloth thickness of presser foot below increases, the cloth of thickening makes the presser foot shift up, and then the drive presser bar shifts up, compresses the second spring, and the trace compression of second spring can make presser foot pressure show and increase to make the pressure that the cloth pressing device applyed can be along with the increase and the rapid increase of cloth thickness to the cloth, it is with defects such as the jump needle that produces when the pure mechanical mode has been solved to the cloth, gauge needle becomes dense, the reliability is high, and is with low costs.

Drawings

Fig. 1 is a schematic structural view of a cloth pressing device of a sewing machine according to the present application, which is a left side view.

Fig. 2 is a cross-sectional view of fig. 1.

Fig. 3 is a schematic structural view of a cloth pressing device of the sewing machine in the application under another view angle.

Description of the element reference numerals

1 case

2 fixed sleeve

3 ejector pin

4 presser foot rod

5 presser foot

51 presser foot main body part

52 cloth guide part

53 spring holding part

54 presser foot connecting part

6 retainer ring

61 collar projection

7 first spring

8 second spring

9 Lever

10 first drive block

11 sleeve

12 piston

13 third spring

14 second drive block

15 supporting plate

151 mounting groove

16 first fixing screw

17 second fixing screw

18 third fixing screw

19 first axis pin

20 second axle pin

21 third axis pin

22 the fourth axis pin

23 spacing retainer ring

24 locking nut

25 cloth

Detailed Description

The following description of the embodiments of the present invention is provided for illustrative purposes, and other advantages and effects of the present invention will become apparent to those skilled in the art from the present disclosure.

It should be understood that the structures, proportions, and dimensions shown in the drawings and described herein are for illustrative purposes only and are not intended to limit the scope of the present invention, which is defined by the claims, but rather by the claims. In addition, the terms such as "upper", "lower", "left", "right", "middle" and "one" used in the present specification are for convenience of description only and are not intended to limit the scope of the present invention, and changes or modifications of the relative relationship thereof may be made without substantial technical changes and modifications.

The invention provides a sewing machine, wherein a cloth pressing device is installed in the sewing machine. For convenience of description, in the following examples, the directions are defined as follows: the cloth feeding direction of the sewing machine is defined as a rear direction, and therefore, a front-rear direction is a width direction of the sewing machine, a left-right direction is a length direction of the sewing machine, and an up-down direction is a height direction of the sewing machine, and at the same time, a direction toward a head of the sewing machine is a left direction, and a direction toward a tail of the sewing machine is a right direction. Alternatively, in the view shown in fig. 1, the left side of the paper surface is the rear direction, the right side of the paper surface is the front direction, the upper side of the paper surface is the upper direction, the lower side of the paper surface is the lower direction, the front side of the paper surface is the left direction, and the back side of the paper surface is the right direction.

As shown in fig. 1 and 2, the cloth pressing device of the sewing machine according to the present application includes a housing 1, a fixing sleeve 2 extending upward and downward, a push rod 3 extending upward and downward, a presser bar 4 extending upward and downward, a presser foot 5, a retainer ring 6, a first spring 7 extending upward and downward, and a second spring 8 extending upward and downward. Wherein, the lower end of the fixed sleeve 2 is fixed on the casing 1; the ejector rod 3 is positioned above the fixed sleeve 2, and the ejector rod 3 is arranged on the machine shell 1; the upper section part of the presser bar 4 is sleeved in the fixed sleeve 2 and positioned below the ejector rod 3 in a manner of freely sliding up and down; the presser foot 5 is arranged at the lower end of the presser foot rod 4; the retainer ring 6 is arranged on the periphery of the presser foot rod 4 and is positioned above the presser foot 5, and meanwhile, the retainer ring 6 is positioned outside the machine shell 1; the upper end of the first spring 7 extends into the lower section of the ejector rod 3 and is abutted against the ejector rod 3, and the lower end of the first spring 7 extends into the fixed sleeve 2 and the presser foot rod 4 from the upper end of the fixed sleeve 2 and is abutted against the presser foot rod 4; the second spring 8 is sleeved on the presser bar 4, the upper end of the second spring 8 extends into the fixed sleeve 2 from the lower end of the fixed sleeve 2 and is abutted against the fixed sleeve 2, and the lower end of the second spring 8 is abutted against the upper end face of the retainer ring 6. In particular, the elastic modulus of the second spring 8 is much greater than that of the first spring 7; in this embodiment, the elastic modulus of the second spring 8 is 3 to 10 times that of the first spring 7. When sewing thin materials, namely in the state of common cloth (usually one to two layers of cloth), the second spring 8 generates no pressure or generates slight pressure, and at the moment, the pressure of the presser foot 5 is provided by the first spring 7; when thick materials are sewn, namely, under the state of multiple layers of cloth (usually at least three layers of cloth), the thickened cloth enables the presser foot 5 to move upwards, so that the presser foot rod 4 and the check ring 6 fixed on the presser foot rod 4 are driven to move upwards, the check ring 6 moves upwards to compress the second spring 8, and the elastic modulus of the second spring 8 is far greater than that of the first spring 7, so that the pressure of the presser foot 5 can be obviously increased by slight compression of the second spring 8. Therefore, the present application utilizes the difference in the elastic modulus of both the first spring 7 and the second spring 8 to achieve: when the cloth becomes thick, the pressure of the presser foot 5 is obviously increased, namely: the pressure applied to the cloth by the cloth pressing device can be rapidly and obviously increased along with the increase of the thickness of the cloth, and the corresponding speed is high. In addition, the defects of needle skipping, needle pitch density changing and the like generated when the material is too thick are overcome in a pure mechanical mode, the reliability is high, and an inductor is not required to be additionally arranged to detect common layer cloth and multilayer cloth, so the cost is low; meanwhile, the method does not need any air source, and is suitable for some factories without air sources.

As shown in fig. 1 and 2, the top rod 3 is an adjusting stud, and the top rod 3 is screwed to the casing 1, so that the top rod 3 can move up or down relative to the casing 1, so that the mounting position of the top rod 3 on the casing 1 can be adjusted in the up-down direction, thereby changing the compression amount of the first spring 7, adjusting the initial pressure of the first spring 7, and further adjusting the pressure of the presser foot 5 in the normal layer material distribution state. The periphery of the ejector rod 3 is also in threaded connection with a locking nut 24, and the lower end face of the locking nut 24 is abutted to the upper end face of the machine shell 1. The retainer ring 6 is fixed on the outer peripheral surface of the presser bar rod 4 by the second fixing screw 17, so that the mounting position of the retainer ring 6 on the presser bar rod 4 is adjustable in the up-down direction, the compression amount of the second spring 8 is adjusted, the initial pressure of the second spring 8 is adjusted, and the second spring 8 does not generate pressure or generates trace pressure in a common layer material distribution state.

Further, as shown in fig. 1 to 3, the cloth pressing device of the sewing machine further includes a lever 9 extending back and forth, a first driving block 10 installed at the rear end of the lever 9, a sleeve 11 fixed at the front end of the lever 9 by a third fixing screw 18, a piston 12 having an upper section fitted in the sleeve 11 so as to be movable up and down, an installation cavity formed by the sleeve 11 and the piston 12, a third spring 13 disposed in the installation cavity, and a second driving block 14 installed at the lower end of the piston 12; the presser foot 5 is hinged at the lower end of the presser foot rod 4 through a first shaft pin 19 extending leftwards and rightwards, the first shaft pin 19 forms the rotation center of the presser foot 5, and the presser foot 5 can rotate relative to the presser foot rod 4 around the first shaft pin; the upper end of the third spring 13 abuts against the sleeve 11, and the lower end of the third spring 13 abuts against the piston 12; a retainer ring protruding part 61 extending backwards is arranged at the rear end of the retainer ring 6, and the first driving block 10 is abutted with the upper end surface of the retainer ring protruding part 61; the second drive block 14 abuts on the upper end surface of the rear end of the presser foot 5. In the process of sewing the cloth, the force applied to the presser foot 5 by the first spring 7 is F1, the force applied to the presser foot 5 by the second spring 8 is F2, and the force applied to the presser foot 5 by the third spring 13 is F3. In a normal cloth layer state or a multi-layer cloth state, the thickness of the cloth is kept unchanged, the lower surface of the presser foot 5 is attached to the upper surface of the cloth and is always in full contact with the cloth, at this time, the third spring 13 has a certain compression amount, but the pressure generated by the third spring 13 is not enough to enable the front end of the presser foot 5 to rotate downwards, and the presser foot 5 does not rotate around the first axis pin 19 and is kept in a state of being attached to and in contact with the cloth. When the common cloth state is transited to the multilayer cloth state, namely when the cloth thickness is increased, the retainer ring 6 moves upwards to enable the first driving block 10 to move upwards, the lever 9 rotates around the fulcrum, the rear end of the lever 9 rises, the front end of the lever 9 descends, the third spring 13 is further compressed, and the elastic force of the third spring 13 is still insufficient to enable the front end of the presser foot 5 to rotate downwards; at this time, when the presser foot 5 is regarded as a lever and a supporting point of the presser foot 5 on the cloth 25 constitutes a fulcrum of the presser foot 5, the following relationship exists: f1+ F2 resistance arm > F3 power arm, so the front end of presser foot 5 does not rotate downward. When the state of the multi-layer cloth is transited to the state of the common-layer cloth, that is, when the thickness of the cloth is reduced, the supporting point of the presser foot 5 on the cloth 25 is changed, at this time, the resistance arm F1+ F2 is less than the power arm F3, and the pressure of the third spring 13 makes the front end of the presser foot 5 rotate downward as shown in fig. 1, so that the presser foot 5 is effectively contacted with the cloth, and the presser foot 5 is prevented from being in a suspended state. The application utilizes the lever principle in many places to combine the rotating force of the presser foot 5 with the rising of the presser foot 5, and utilizes the action of the third spring 13 and the piston 12 to change the downward rotating force of the front end of the presser foot 5 into movable connection.

In this embodiment, as shown in fig. 1 and 3, the first driving block 10 is a roller and is rotatably mounted at the rear end of the lever 9 by a second shaft pin 20 extending left and right, the second driving block 14 is a roller and is rotatably mounted at the lower end of the piston 12 by a third shaft pin 21 extending left and right, and the friction between the first driving block 10 and the retainer ring 6 and the friction between the second driving block 14 and the presser foot 5 can be converted from sliding friction to rolling friction by the roller, so as to reduce resistance and noise and move free of jamming. The piston 12 can only move axially along the sleeve 11 but can not rotate in the sleeve 11, and the movement can be realized by a limit component; the limiting assembly can comprise a limiting protruding part arranged on the outer wall of the piston 12 and a limiting groove arranged on the inner wall of the sleeve 11, the limiting groove extends along the axial direction of the sleeve 11, and the limiting protruding part of the piston 12 is in sliding fit with the limiting groove of the sleeve 11.

The mounting structure of the lever 9 is: as shown in fig. 1 and 3, the cloth pressing device of the sewing machine further includes a support plate 15 extending up and down, an upper end of the support plate 15 is fixed to the machine case 1, a lower end of the support plate 15 is hinged to the lever 9, and a hinge point of the support plate 15 and the lever 9 constitutes a fulcrum of the lever 9. In addition, the supporting plate 15 is mounted on the casing 1 through a first fixing screw 16, an installation groove 151 extending up and down along the length direction of the supporting plate 15 is formed at the upper end of the supporting plate 15, and the first fixing screw 16 penetrates through the installation groove 151; after the first fixing screw 16 is unscrewed, the mounting position of the upper end of the supporting plate 15 on the casing 1 can be adjusted in the vertical direction, and thus the initial pre-pressure of the third spring 13 can be adjusted. The hinge structure of the support plate 15 and the lever 9 is as follows: a fourth shaft pin 22 extending left and right is arranged in the lever 9 in a penetrating manner, the lever 9 can rotate around the fourth shaft pin 22, and the fourth shaft pin 22 forms a fulcrum of the lever 9; the left end of the fourth shaft pin 22 is fixed at the lower end of the support plate 15; meanwhile, in order to enable the lever 9 to have a certain position in the axial direction of the fourth shaft pin 22, a limit stop 23 is further fixed on the fourth shaft pin 22, and a head part of the right end of the fourth shaft pin 22 and the limit stop 23 abut against the right side and the left side of the lever 9 respectively.

The presser foot 5 preferably adopts the following structure: as shown in fig. 3, the presser foot 5 includes a horizontally extending presser foot main body portion 51, a cloth guide portion 52 extending obliquely forward and upward from a front end of the presser foot main body portion 51, and a spring holding portion 53 extending obliquely rearward and upward from an upper end of the cloth guide portion 52, and the second drive block 14 abuts against an upper end surface of the spring holding portion 53. The cloth can easily enter the lower part of the presser foot main body part 51 through the cloth guide part 52 with a certain angle; when the state of multi-layer cloth is transited to the state of common-layer cloth, the pressure of the third spring 13 can enable the front end of the presser foot 5 to rotate downwards, at the moment, the second driving block 14 can be prevented from descending through the spring holding part 53 with a certain angle, the pressure of the third spring 13 is further prevented from being reduced, and the problem that the pressure value of the third spring 13 is reduced due to the descending of the front end of the presser foot 5 is effectively solved. In addition, the presser foot 5 further includes presser foot connecting portions 54 vertically extending upward from both left and right sides of the front section portion of the presser foot main body portion 51, the lower end of the presser foot rod 4 is positioned between the two presser foot connecting portions 54, and the presser foot rod 4 is hinged to the presser foot connecting portions 54 by a first pin shaft; meanwhile, a self-locking nut is screwed to the right end of the first shaft pin 19, and the self-locking nut abuts against the outer peripheral surface of the presser foot connecting portion 54. The presser foot 5 having the above-described structure is preferably a single piece.

In conclusion, the present invention effectively overcomes various disadvantages of the prior art and has high industrial utilization value.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.

Claims (10)

1. A cloth pressing device of a sewing machine is characterized in that: comprises a machine shell (1), a fixed sleeve (2) fixed on the machine shell (1), a push rod (3) arranged on the machine shell (1) and positioned above the fixed sleeve (2), a presser bar (4) sleeved in the fixed sleeve (2) in a vertically movable manner, a presser foot (5) arranged at the lower end of the presser bar (4), a check ring (6) arranged at the periphery of the presser bar (4), a first spring (7), a second spring (8) sleeved on the presser bar (4), a lever (9) extending forwards and backwards along the cloth feeding direction of the sewing machine for feeding cloth backwards, a first driving block (10) arranged at the rear end of the lever (9), a sleeve (11) fixed at the front end of the lever (9), a piston (12) sleeved in the sleeve (11) in a vertically movable manner at the upper section, an installation inner cavity formed by the sleeve (11) and the piston (12), a third spring (13) arranged in the installation inner cavity, The upper end and the lower end of the first spring (7) are respectively abutted to the ejector rod (3) and the presser bar (4), the upper end and the lower end of the second spring (8) are respectively abutted to the fixed sleeve (2) and the check ring (6), the elastic modulus of the second spring (8) is larger than that of the first spring (7), the presser bar (5) is hinged to the presser bar (4), the upper end and the lower end of the third spring (13) are respectively abutted to the sleeve (11) and the piston (12), the first driving block (10) is abutted to the check ring (6), and the second driving block (14) is abutted to the presser bar (5); as the thickness of the cloth increased, (F1+ F2) resistance arm > F3 power arm; when the thickness of the cloth is reduced, (F1+ F2) resistance arm < F3 power arm, the front end of the presser foot (5) is rotated downwards; the F1 is the force applied to the presser foot (5) by the first spring (7), the F2 is the force applied to the presser foot (5) by the second spring (8), and the F3 is the force applied to the presser foot (5) by the third spring (13).

2. Cloth pressing apparatus according to claim 1, characterized in that: the first driving block (10) is a roller and is rotatably arranged at the rear end of the lever (9), and the second driving block (14) is a roller and is rotatably arranged at the lower end of the piston (12).

3. Cloth pressing apparatus according to claim 1, characterized in that: the presser foot (5) includes a presser foot main body portion (51) extending horizontally, a cloth guide portion (52) extending obliquely forward and upward from a front end of the presser foot main body portion (51), and a spring holding portion (53) extending obliquely rearward and upward from an upper end of the cloth guide portion (52), and the second drive block (14) abuts against an upper end face of the spring holding portion (53).

4. Cloth pressing apparatus according to claim 3, characterized in that: the presser foot (5) is an integrated piece.

5. Cloth pressing apparatus according to claim 1, characterized in that: the hinge mechanism is characterized by further comprising a supporting plate (15), the upper end of the supporting plate (15) is fixed on the machine shell (1), the lower end of the supporting plate (15) is hinged to the lever (9), and a hinge point of the supporting plate (15) and the lever (9) forms a fulcrum of the lever (9).

6. Cloth pressing apparatus according to claim 5, characterized in that: the supporting plate (15) is installed on the machine shell (1) through a first fixing screw (16), an installation groove (151) extending along the length direction of the supporting plate (15) is formed in the upper end of the supporting plate (15), the first fixing screw (16) penetrates through the installation groove (151), and the installation position of the supporting plate (15) on the machine shell (1) is adjustable in the extending direction of the installation groove (151).

7. Cloth pressing apparatus according to claim 1, characterized in that: the elastic modulus of the second spring (8) is 3-10 times of that of the first spring (7).

8. Cloth pressing apparatus according to claim 1, characterized in that: the ejector rod (3) is in threaded connection with the machine shell (1), and the installation position of the ejector rod (3) on the machine shell (1) is adjustable in the up-down direction.

9. Cloth pressing apparatus according to claim 1, characterized in that: the retainer ring (6) is fixed on the presser foot rod (4) through a second fixing screw (17), and the mounting position of the retainer ring (6) on the presser foot rod (4) is adjustable in the up-down direction.

10. A sewing machine characterized by: a sewing machine having installed therein a cloth pressing device according to any one of claims 1 to 9.

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