KR102632181B1 - Sewing machine - Google Patents

Abstract

The sewing machine of the present invention has at least one sewing foot for holding the fabric piece during sewing. The pressure regulating device is used to set the pressing pressure applied by the sewing foot when holding the fabric piece.
A lifting device is provided to lift the sewing foot. The sewing machine has a common drive 12 for the pressure regulating device and the lifting device. The cam disk 13 is non-rotatingly arranged on the drive axis of the common drive 12, on the one hand for lifting the sewing foot and on the other hand for driving the pressure regulating device. interacts with the cam lever (14) for this purpose. The cam lever 14 interacts with the cam disk 13 along the entire pivot path. The cam lever 14 has two cam followers 22 , 24 arranged separately from each other and in each case cooperating with the cam disc 13 in at least a part of the overall swiveling path of the cam disc 13 . As a result, the operational safety of the common drive for the pressure regulating device on the one hand and the lifting device on the other is improved.

Description

Sewing machine{SEWING MACHINE}

The disclosure of German patent application DE 10 2018 206 088.6 is incorporated herein by reference.

The present invention relates to sewing machines.

This type of sewing machine is known from patent document EP 2 975 169 B1 and patent document EP 2 105 526 B1. Patent document CN 202658372 U discloses a sewing foot lifting device comprising a stepper motor that interacts with other components of the lifting device via a cam disk. Patent document JP 07-231 991 A discloses a sewing machine with a presser foot drive. Patent document EP 2 351 881 A1 discloses a multi-head embroidery machine with a transmission for the fabric presser of the fabric presser device. Patent application document US 2018/0016722 A1 discloses a sewing machine. A presser foot lifting device for a sewing machine is known from document DE-PS 292 059.

The object of the invention is to increase the operational safety of the common drive for the pressure regulating device on the one hand and the lifting device on the other.

According to the invention, this purpose is achieved by at least one sewing foot for holding the fabric piece during sewing, a pressure regulating device for setting the pressing pressure applied by the sewing foot when holding the fabric piece, and a lifting device for lifting the sewing foot. having a common drive for the device, the pressure regulating device and the lifting device, wherein a cam disc interacting with the cam lever to lift the sewing foot on the one hand and drive the pressure regulating device on the other hand is mounted on a drive shaft of the common drive. non-rotatingly disposed on the cam, the cam lever being configured to interact with the cam disk along the entire pivot path of the cam disk, the cam lever having two cam followers disposed separately from each other, the cam followers in each case cam This is achieved by a sewing machine arranged to interact with the cam disk at least in part of the overall pivot path of the disk.

The basic configuration of a common drive for the pressure regulating device on the one hand and the lifting device on the other is known from EP 2 975 169 B1 and this creates a significantly simplified sewing machine design. One drive can be omitted. Associated control components may also be omitted. The common drive can be configured so as not to impair the essentially independent functions of “foot lifting” and “pressure regulation”. By omitting the drive, the overall design becomes more economical and more compact. The design of the cam lever with two cam followers arranged separately from each other so as to interact with the cam disc in each case at least part of the entire swiveling path of the cam disc ensures that the transfer of movement between the cam disc and the cam lever is carried out safely. It can be guaranteed. When transmitting force between the cam disk and each cam follower of the cam lever, an undesirable force transmission direction can be prevented. An undefined separation of the cam lever from the cam disk can thus be prevented. The cam follower may be a separate but firmly attached component from the rest of the cam lever. Alternatively, the cam follower can be a section of the cam lever itself. A cam disk can have exactly one cam for interaction with both cam followers. In this case, the two cam followers can interact with different cam sections of one and the same cam of the cam disk.

The simultaneous interaction of the cam disc and the cam follower of the cam lever in at least part of the entire pivot path of the cam disc can ensure a particularly safe frictional connection between the cam lever and the cam disc. A "foot lifting" function can be performed in the drive area in a portion of the total swiveling range of the cam disc in which the two cam followers interact simultaneously with the cam disc. There, the cam lever can be prevented from undesirably losing its frictional connection with the cam disk, and an undefined state of the common drive can be prevented, for example when sewing thick pieces of fabric.

Due to an embodiment in which the cams of the cam disk have convex cam sections on both sides of which each concave cam section is adjacent, and the simultaneous interaction of the two cam followers with the cam disk occurs through the convex cam sections, This creates a particularly safe frictional connection between the cam lever and the cam disc in at least part of the entire pivot path. In an embodiment of this type, the two cam followers may comprise an area of the cam section that is convex, thus making it possible to obtain a positive locking contribution of the force transmission connection between the cam lever and the cam disk. The two cam followers may interact with the convex cam section in the manner of two interlocking gear sections.

Embodiments of cam followers such as those rigidly connected to the cam lever are economical and operationally safe.

The interaction of the cam disc and the cam lever, such that the lifting of the sewing foot occurs in one direction of rotation of the cam while the actuation of the pressure regulating device occurs in the opposite direction of rotation, on the one hand for the foot lifting and on the other. This results in the desired decoupling of the mechanical transmission element for pressure regulation.

Setting the cam lever position, referred to as “minimum push pressure”, by means of a cam recess formed in the cam disc allows a defined setting of the minimum push pressure.

The lifting axis, which transmits the switch operating force from the cam lever to the sewing foot, ensures that the drive is placed at a certain distance from the sewing foot. When viewed in a plane perpendicular to the lifting axis, the cam follower can be arranged between the lifting axis and the drive axis of the common drive. This type of arrangement can simplify the cam design of the cam disk.

Drives consisting of stepper motors enable particularly gradual setting of the pressing pressure. This can be used to adapt to each sewing environment. Fine adjustment of the lifting device height is also advantageous. When sewing thick pieces of fabric, you can set a high lifter height. When sewing thin pieces of fabric, you can set a lower lifter height.

The arrangement of the drive may be such that the drive axis of the drive, especially the stepper motor, is oriented in a direction towards the sewing foot of the sewing machine, or alternatively the drive axis may be oriented in a direction away from the sewing foot. Depending on the space requirements for the drive in the horizontal or vertical direction of the sewing machine arm, for example, this allows the drive to be compactly designed in critical dimensions.

The adjustment range of the drive axis of the common drive between the "minimum push pressure" cam lever position and the "maximum push pressure" cam lever position greater than 180° allows fine adjustment of the push pressure without excessive demands on drive increase or positioning accuracy. do. With this wide adjustment range, low torque drives and cam discs with small pitch cams can be achieved simultaneously.

It has also been recognized that a cam lever with two cam followers arranged separately from each other and a cam disk with a corresponding shape can also be used as an assembly group for retrofitting. This allows an already existing drive comprising a cam lever with exactly one cam follower to be replaced by a drive according to the invention comprising two cam followers, resulting in a correspondingly safe force transmission between the cam lever and the cam disc. .

Exemplary embodiments of the invention will be described in greater detail below with reference to the drawings:
1 is a front perspective view of a sewing machine;
Figure 2 shows an assembly of the sewing machine shown in Figure 1, having a pressure regulating device for setting the pressing pressure exerted by the sewing foot when holding a piece of fabric, a lifting device for lifting the sewing foot and a common drive for these devices; Another perspective view of the group;
Fig. 3 is a top view of the assembly group as shown in Fig. 2, viewed from the line of sight (III) in the “minimum pressing pressure” position;
Figure 4 is a view as shown in Figure 3, with part of the base plate of the cam lever of the drive omitted;
Figure 5 is a view similar to Figure 3 of the assembly group in the “maximum foot lifting” position;
Figure 6 is a view of the same group of assemblies as shown in Figure 5, with part of the base plate of the cam lever again omitted;
Figure 7 is a view similar to Figure 3 of the assembly group in the “mid foot lifting height” position;
Fig. 8 is a view of the assembly group shown in Fig. 7, again with part of the base plate of the cam lever omitted;
Figure 9 is a view similar to Figure 3 of the assembly group in the “maximum pressing pressure” position;
Fig. 10 is a view of the assembly group shown in Fig. 9, again with part of the base plate of the cam lever omitted;
Figure 11 shows a group of assemblies, similar to Figure 2, comprising a pressure regulating device for setting the pressing pressure exerted by the sewing foot when holding a piece of fabric, a lifting device for lifting the sewing foot and a common drive for these devices. As an illustration of another embodiment, the group of assemblies shown in Figure 11 may be used in place of the group of assemblies shown in Figure 2;
Fig. 12 is a plan view of the assembly group as shown in Fig. 11 from the line of sight (XII) in the “minimum pressing pressure” position, with a portion of the base plate of the cam lever omitted, similar to Fig. 4;
Figure 13 is a view similar to Figure 12 of the assembly group in the “maximum foot lifting” position;
Figure 14 is a view similar to Figure 12 of the assembly group in the “mid foot lifting height” position;
Fig. 15 is a view similar to Fig. 12 of the assembly group in the “minimum pressing pressure” position;
Figure 16 is a perspective view of the cam disk of the assembly group shown in Figure 11; and
Figure 17 shows a perspective view of a cam lever of the assembly group as shown in Figure 11;

The sewing machine 1 has a stand 2, an arm 3 and a head 4, so that together with the base plate 5 an overall C-shaped structure of the sewing machine 1 is obtained. The arm axis driven by the main drive unit, which is not shown in detail, drives the needle bar 6 with the fixed sewing needle 7 in repetitive up and down movements. During this movement, the needle 7 passes through a needle hole in the needle plate forming part of the support plate 8, which is the upper surface of the housing base plate 5 of the sewing machine 1.

The sewing machine 1 has a sewing foot 9 for pressing down a piece of fabric during sewing, and the sewing foot is also referred to as a presser foot. The sewing foot (9) is mounted on the presser foot stand (10).

The assembly, designated throughout in Figure 2 by reference numeral 11, is used to set the pressure exerted by the sewing foot 9 and to lift the sewing foot when holding a piece of fabric.

The assembly 11 includes a pressure regulating device for setting the pressing pressure, a lifting device for lifting the sewing foot and a common drive for both devices. The pressure regulating device and lifting device are described in detail below. The common drive consists of a stepper motor (12). The drive axis 12a of the stepper motor 12 (e.g., see Figure 3) is oriented away from the presser foot stand 10 and thus the free end of the drive axis 12a is in the field of view as shown in Figure 3. It proceeds toward the observer in a direction opposite to direction (III).

The drive shaft of the stepper motor 12 is non-rotatingly connected to the cam disk 13. The cam disk 13 interacts with the cam lever 14 to lift the sewing foot 9 on the one hand and to drive the pressure regulating device on the other hand. The cam lever 14 interacts with the cam disk 13 along the entire pivot path of the cam disk 13. The cam lever 14 is in turn non-rotatingly connected to a lifting shaft 15 running parallel to the arm axis of the arm 3 of the sewing machine 1 and rotatably mounted on the frame of the sewing machine 1. A lifting lever (16) non-rotatingly connected to the lifting axis (15) interacts with a presser foot driver (17) rigidly connected to the presser foot stem (10). The lifting shaft 15 is used to transmit the switch operating force from the cam lever 14 to the sewing foot 9.

At the end opposite the cam lever 14, the lifting axis 15 is connected in an eccentric manner with respect to the longitudinal axis of the lifting axis to a tension bar 18, which is not shown in Figure 2. The compression spring (21) is pressed from above by the sleeve (19) so as to press the sewing foot (9) that is not attached.

A compression spring 21 that spirally surrounds a portion of the presser foot stand 10 is disposed between the presser foot driver 17 and another sleeve 20 that is fixed to the frame and through which the presser foot stand 10 passes.

2 and 4 show the assembly 11 in the drive position “minimum pressing pressure”. Compared to Figure 3, a portion of the base plate of the cam lever 14 is not shown in Figure 4 to illustrate its interaction with the cam lever 14.

The first follower stud 22 of the cam lever 14 forms the first cam follower of the cam lever 14 and the cam recess 23 of the cam disk 13 defines the “minimum push pressure” cam lever position. is combined with In the relevant pivot position of the lifting axis 15, the tension bar 18 exerts a minimal compressive force on the sleeve 19. Compression spring 21 is minimally biased. The force of the compression spring 21 is transmitted to the presser foot stand 10 by the presser foot driver 17, so that a corresponding minimum pressing pressure of the sewing foot 9 is generated during operation of the sewing machine 1. In this “minimum pressing pressure” driving position, the lifting lever 16 is disengaged from the presser foot driver 17.

Figures 5 and 6 show the “maximum foot lifting” drive position. To reach this position, the stepper motor 12 advances from the “minimum push pressure” position shown in Figures 2 to 4 in such a way that the drive shaft is rotated approximately 80° counterclockwise from the diagrams in Figures 3 to 6. It works. As a result, the second follower stud 24 of the cam lever 14, which forms the second cam follower of the cam lever 14, is a cam with the cam disk 13 acting as a lever on the second follower stud 24. It continues on the cam disk 13 in a clockwise direction up to area 25. In this position, the lifting lever (16) presses the presser foot driver (17) in an upward direction against the compression force of the compression spring (21) in the direction of the sleeve (20) fixed to the frame and lifts the sewing foot (9). It is transported along the presser foot stand (10).

The two follower studs 22 and 24 of the cam lever 14 are arranged separately from each other. The two follower studs (22, 24) are tightly connected to the cam lever (14).

The two follower studs 22 and 24 are each arranged in such a way that they interact with the cam disk 13 in at least a portion of the overall pivot path of the cam disk 13. In the part of the pivot path in the “minimum pressing pressure” cam lever position (see FIGS. 3 and 4 ), the first follower stud 22 interacts with the cam disc 13 in the area of the cam recess 23 . In the subsequent “maximum foot lifting” cam lever position (see Figures 5 and 6), the second follower stud 24 interacts with the cam area 25.

Cam recess 23 and cam area 25 are two concave cam sections of cam disk 13. The cam disk 13 between these two concave cam sections has a convex cam section 26 and is configured in the manner of curved lobes of the cam disk 13.

7 and 8 show the “intermediate foot lifting height” drive position between the two drive positions “minimum pressing pressure” and “maximum foot lifting” described above. In this “mid-foot lifting height” drive position, the convex cam section (26) engages the space between the two follower studs (22, 24) to ensure safe contact of the cam lever (14) with the cam disc (13). Provides a positive locking force contribution. Safe contact with the cam disk 13 is ensured regardless of the force transmitted to the cam lever 14 through, for example, a piece of fabric, the sewing foot 9 and the presser foot stand 10.

In a part of the area between the "minimum pressing pressure" drive position (see, for example, Figures 3 and 4) and the "maximum foot lifting" drive position (see Figures 5 and 6), the two follower studs 22, 24 are simultaneously They interact with the cam disc 13, i.e. they are in contact with the cam disc 13 at the same time.

Figures 9 and 10 show the “maximum pressing pressure” actuation position. Compared to Figure 3, the stepper motor 12 has been modified so that its drive axis pivots the cam disk 13 through approximately 320° clockwise compared to the position shown in Figure 3. The first follower stud 22 of the cam lever 14 moves along the cam disc 13 up to the “maximum pressing pressure” cam area 27 . In this “maximum pressing pressure” position, the second follower stud (24) is disengaged from the cam disk (13).

In this position, the tension bar 18 moves downward due to its eccentric connection to the lifting axis 15 and thus exerts a tension on the sleeve 19, which is thus maximally pressed by the tension bar 18. As a result, the compression spring 21 is maximally biased. As a result, the presser foot bar 10 and the corresponding sewing foot 9 exert maximum pressing pressure on the fabric piece during operation of the sewing machine 1. In the “maximum pressing pressure” position, the lifting lever 16 is again disengaged from the presser foot driver 17. Accordingly, the cam lever 14 in the "maximum push pressure" drive position shown in FIGS. 9 and 10 rotates through approximately 60° compared to the "minimum push pressure" drive position shown in FIG. 3. Make sure to turn clockwise.

Accordingly, the cam disk 13 and the cam lever 14 interact in such a way that while the lifting of the sewing foot 9 occurs in one rotational direction of the cam rotation, the driving of the pressure regulating device occurs in the opposite rotational direction. do.

The adjustment range of the drive shaft of the stepper motor 12 between the “minimum push pressure” cam lever position (see FIG. 3) and the “maximum push pressure” cam lever position (see FIG. 5) is greater than 180°.

The stepper motor 12 can be actuated, for example, for foot lifting by the operator via the pedal of the sewing machine 1 .

To set the pressing pressure, the setting can be performed by means of a control device 26 schematically shown in FIG. 1 . The control device 26 has a signal connection to the stepper motor 12 in a manner not shown in more detail.

Another embodiment of a group of assemblies 28 for setting the pressing pressure and lifting the sewing foot, which can be used in the sewing machine 1 instead of the group of assemblies 11 described above, will be described below with reference to FIGS. 11 to 15. . Components and functions corresponding to those already described above with reference to the assembly 11 group are indicated with the same reference numerals and will not be discussed in detail again.

In the assembly group 28, the stepper motor 12 is oriented with its drive axis in the direction towards the presser foot stand 10, i.e. towards the viewer in FIG. 12, i.e. opposite to the viewing direction XII. It is arranged to be oriented. Accordingly, in the assembly group 28, the direction of the drive axis of the stepper motor 12 relative to the presser foot stand 10 is opposite to that of the assembly group 11.

Figures 11 and 12 show the “minimum pressing pressure” drive position. In this position, the first follower stud 22 of the cam lever 14 again lies in the cam recess 23 of the cam disk 13.

Figure 13 shows the “maximum foot lifting” drive position. In this position, the stepper motor 12 of the assembly group 28 advances from the "minimum pressing pressure" drive position shown in Figure 12, with the cam disk 13 rigidly connected to its drive shaft, as shown in Figures 12 and 13. It was rotated approximately 180° counterclockwise as it was setting. In this “maximum foot lifting” drive position, the second follower stud 24 engages the other recessed cam area 25 of the cam disc 13 corresponding to the cam area 25 of the assembly group 11 . Proceeding from the "minimum foot pressure" drive position, this pivoting movement of the cam disk 13 is such that the cam lever 14 is pivoted counterclockwise by approximately 45°. In this position, as already explained above for the assembly group 11 with reference to Figures 5 and 6, the lifter lever 16 moves the presser foot driver 17 in a direction opposite to the compression force of the compression spring 21 and against the frame. Press the presser foot driver (17) upward again in the direction of the sleeve (20) fixed to.

FIG. 14 shows the “intermediate foot lifting” drive position, i.e. the drive position intermediate between the “minimum foot pressure” position shown in FIG. 12 and the “maximum foot lifting” position shown in FIG. 13 . In this “mid-foot lifting height” drive position, the two drive studs 22, 24 interact simultaneously with the convex cam section 26 of the cam disc 13.

Between the two concave cam areas of the cam disc 13 of the assembly group 28, there is a larger volume within the cam disc 13 of the assembly group 28 than within the cam disc 13 of the assembly group 11. There is another convex cam section 26 having the shape.

Figure 15 shows the “maximum pressing pressure” drive position. Compared to the driving position shown in Figure 12, the cam disk 13 of the assembly group 28 is again rotated by about 210° clockwise by the stepper motor 12. The first follower stud (22) holds the cam disk (13) of the assembly group (28) up to the “maximum pressing pressure” cam portion (27). In this “maximum push pressure” drive position, the cam lever 14 has been rotated about 90° clockwise compared to the “minimum foot pressure” drive position shown in Figures 12 and 15.

In this position, the tension bar 18 is moved downward due to its eccentric connection to the lifting axis 15, which applies a corresponding tension force to the sleeve 19, which is thus pushed down to its maximum by the tension bar 18. It is pressurized. This causes the compression spring 21 to be maximally biased. As a result, during the operation of the sewing machine 1, the maximum pressing pressure is applied by the presser foot bar 10 to the fabric piece and, accordingly, to the sewing foot 9. In the “maximum pressing pressure” position, the lifting lever 16 is again disengaged from the presser foot driver 17. In this “maximum pressing pressure” position, the second follower stud (24) is disengaged from the cam disk (13).

In the “maximum push pressure” position, the cam area 27 is also used as a stop for referencing the stepper motor 12. For this purpose, the stepper motor 12 moves to the “maximum pressing pressure” drive position until the first follower stud 22 rests on the stop formed by the cam area 27. The cam area 27 configured as a stop does not require the use of other reference sensors, which could otherwise be formed by light barriers or inductive switches.

In the “minimum pressing pressure” driving position (see FIGS. 3 and 4 ), the two followers 22 , 24 of the assembly group 11 , for example in the top view as shown in FIGS. 3 and 4 , are connected to a stepper motor 12 ) is disposed between the lifting shaft 15 and the driving shaft 12a. In the “maximum foot lifting” drive position (see Figure 13), for example in a top view as shown in Figure 13, the two follower studs 22, 24 of the assembly group 28 are connected to the drive shaft of the stepper motor 12. It is approximately on the same plane as (12a).

Figures 16 and 17 each show a perspective view of the cam disk 13 (Figure 16) and the cam lever (Figure 17) of the assembly group 28.

The cam disk 13 and cam lever 14 of the assembly group 28 can be used as a retrofit assembly group for the modification of an existing drive assembly group, where exactly one follower is provided on the lifting lever of the existing drive assembly group. there is.

Claims (10)

As a sewing machine (1),
At least one sewing foot (9) for holding the fabric piece during sewing,
an assembly (11) comprising a common drive for the action of setting the pressure exerted by the sewing foot (9) and lifting the sewing foot (9) when holding the piece of fabric,
There is a cam disk 13 that interacts with the cam lever 14 to lift the sewing foot 9 on the one hand and drive it to set the pressure applied by the sewing foot 9 on the other hand. Non-rotatingly disposed on the drive axis of the common drive (12), the cam lever (14) is configured to interact with the cam disk (13) along its entire pivot path,
The cam lever 14 has two cam followers 22, 24 disposed separately from each other, and in each case, the cam followers 22, 24 rotate in at least a portion of the entire swing path of the cam disk 13. A sewing machine arranged to interact with the cam disk (13). According to claim 1,
The sewing machine is characterized in that the two cam followers (22, 24) are arranged to interact simultaneously with the cam disk (13) in at least a part of the entire pivot path of the cam disk (13). According to claim 2,
The cam of the cam disk 13 has convex cam sections 26 adjacent to each of the concave cam sections 23 and 25 on both sides, and is connected to the two cam followers through the convex cam sections 26. A sewing machine, characterized in that simultaneous interaction of 22, 24) and said cam disk (13) occurs. According to claim 1,
The sewing machine is characterized in that the two cam followers (22, 24) are configured as followers rigidly connected to the cam lever (14). According to claim 1,
The cam disk 13 and the cam lever 14 are used to set the pressing pressure applied by the sewing foot 9 at the same time that lifting of the sewing foot 9 occurs in one rotation direction of the cam rotation. A sewing machine characterized in that the drives interact so that they occur in opposite directions of rotation. According to claim 1,
Sewing machine, characterized in that the cam disk (13) has a cam recess (23) for setting the “minimum pressing pressure” cam lever position. According to claim 1,
Sewing machine, characterized by a lifting shaft (15) for transmitting switch actuation force from the cam lever (14) to the sewing foot (9). According to claim 1,
Sewing machine, characterized in that the drive (12) is configured as a stepper motor (12). According to claim 1,
A sewing machine characterized by an adjustment range of the drive axis of the common drive (12) between the "minimum push pressure" cam lever position and the "maximum push pressure" cam lever position of greater than 180°. A group of retrofit assemblies for use in the sewing machine of claim 1, comprising:
A cam disk (13) positionable on the drive axis (12a) of the common drive (12),
A cam lever that interacts with the cam disk 13 to lift the sewing foot 9 on the one hand and to drive it to set the pressing pressure applied by the sewing foot 9 on the other hand. (14),
The cam lever (14) is configured to interact with the cam disk (13) along the entire pivot path of the cam disk (13),
The cam lever 14 has two cam followers 22, 24 arranged separately from each other, and in each case, the cam followers 22, 24 form at least a portion of the entire swing path of the cam disk 13. A group of retrofit assemblies arranged to interact with the cam disk (13).