CN101429710B

CN101429710B - Sewing machine

Info

Publication number: CN101429710B
Application number: CN2008101741443A
Authority: CN
Inventors: A·奥泊恩德费尔; T·约尔旦; H·博尔
Original assignee: Duerkopp Adler AG
Current assignee: Dukepu Aihua Co ltd
Priority date: 2007-11-07
Filing date: 2008-11-07
Publication date: 2012-11-21
Anticipated expiration: 2028-11-07
Also published as: DE102007052876A1; DE102007052876A8; KR20090047374A; EP2058426A1; CN101429710A; EP2058426B1; JP2009112819A; JP5346556B2; DE502008002121D1; KR101468744B1

Abstract

The invention relates to a sewing machine comprising a housing (5), a supporting plate (9), a presser foot (10), which interact with the supporting plate for fixing of a work piece (7,8). A power source (16) is provided, which supports on the one hand at the housing (5) and on the other hand at the presser foot, where the presser foot is linked against the supporting plate. An adjustment means 20 is provided which adjusting a preloading force applied on the presser foot by said power source. The adjustment means comprises an adjuster (21) mounted in the housing and pivoted around a pivoting axial line (23). The adjuster comprises an outerwall (24) through which the adjuster affects the preloading force based on the power source. In an adjustable angle region (25) around the pivoted axial line, the radius of the outerwall continuously and strict monotonously changes. Thus a sewing machine with more reliable and comfortable adjustment of the presser foot is obtained.

Description

Sewing machine

Technical Field

The invention relates to a sewing machine, comprising:

-a housing;

-a support plate;

-a presser foot cooperating with the support plate to clamp the fabric;

a force source which is supported on the housing on the one hand and on the presser foot on the other hand, so that the presser foot is preloaded against the support plate; and

-adjusting means for adjusting the preload force exerted on the presser foot by said force source.

Background

Sewing machines of this type are disclosed in DD-PS 53542, DD-PS 35150 and GB 2068027 a. Other sewing machines having adjustable presser foot preload forces are known from the prior disclosures.

In known sewing machines, adjustment of the presser foot preload force still requires improvement. Problems arise in particular in terms of reproducibility of the preload force, preload force adjustment accuracy and readability of the currently set preload force. In addition, adjustment of the preload force often requires a great deal of effort, and some known sewing machines even require the use of additional tools.

Disclosure of Invention

It is therefore an object of the present invention to develop a sewing machine of the type mentioned at the outset in order to achieve a more reliable and comfortable way of adjusting the presser foot preload force.

According to the invention, this object is achieved by a sewing machine of the type mentioned at the outset in which,

the adjustment device comprises an adjustment body mounted in the housing so as to be pivotable about a pivot axis;

-wherein the adjustment body comprises an outer wall,

via the outer wall, the adjusting body bears directly against the force source for influencing the preload force, and

the radius of the outer wall varies monotonically between a minimum radius and a larger maximum radius over an angular range of adjustment about the pivot axis;

-wherein the force source is a leaf spring, wherein

The first end portion of the leaf spring is clamped to be locked relative to the housing,

-the opposite end portion of the leaf spring abuts against an end of a presser bar of the presser foot, which end is opposite to the foot member of the presser foot, and

between the two end portions, the outer wall of the adjustment body directly abuts against the leaf spring.

According to the invention, it has been found that an adjustment device comprising an adjustment body which cooperates with a force source via an outer wall with a varying radius to generate a preload force enables a precise adjustment of the preload force with a particularly short travel distance. The radius changes monotonically in a mathematical sense. The monotonic change in radius according to the invention enables the preloading force to be clearly assigned to the respective position of the adjusting body. This ensures a very precise adjustment of the preload force. The change in radius may be continuous or discontinuous. According to the invention, the gradual or even decreasing change of the radius over the entire adjustment angle range is also monotonous. The discontinuous change in radius may, for example, comprise a plurality of discrete radius steps. The change in radius between the minimum and maximum radii is approximately strictly monotonic. Embodiments in accordance with the present invention enable a legible preload force indicator, such as a digital scale or a linear scale, to be provided over a range of adjustment angles. The leaf spring according to the invention is a force spring (force spring) which has proven to be suitable for adjusting the presser foot preload force. This provides for a sensitive adjustment of the preload force due to the fact that the adjustment body is directly against the force source for influencing the preload force, in other words without the need for further intermediate components. No other mechanism causing additional force between the adjustment body and the leaf spring is required to facilitate adjustment of the preload force.

The substantially helical outer wall of the adjustment body over the adjustment angle range enables the preload force to be continuously adjusted. The helical shape enables the preload force to be generated gradually over the adjustment angle range.

An adjustment wheel arranged on the outer side of the housing and mechanically connected with the adjustment body for pivoting the adjustment body provides for a comfortable operation of the adjustment device. The adjustment wheel may be provided with the above-mentioned scale which cooperates with a marking on the housing to indicate the currently set preload force.

The locking unit for locking the adjustment wheel in at least two pivoting angle locking positions relative to the housing enables the preload force to be set such that it is reproducible and not changed accidentally. No locking means, such as a counter nut, which is inconvenient to use, is required.

A particularly comfortable operation is ensured by the locking unit being designed as a latching unit with a preloaded latching body which cooperates in a latching position with one of the at least two latching grooves. The latching unit enables different default preload values to be set by a click sound. Depending on the design of the latch unit, the latch body may be mounted in the housing and the latch groove may be provided in the adjustment wheel, or the latch body may be mounted in the adjustment wheel and the latch groove may be provided in the housing.

An adjustment angle range of greater than 180 ° or equal to 270 ° ensures a fine adjustment of the preload force.

The radius of the outer wall ensures a force coverage between a minimum and a maximum preload force, which is well adapted to the operating requirements of the sewing machine, the radius of the outer coin being within the adjustment angle range at a minimum radius R_minAnd a maximum radius R_maxSo that the radius ratio R is changed_max/R_min>2。

Drawings

Embodiments of the invention will be described in more detail below with the aid of the accompanying drawings, in which:

FIG. 1 shows a side view of an upper portion of a sewing machine;

fig. 2 shows a schematic vertical longitudinal section of the head region of the sewing machine according to fig. 1, which only shows the components that cooperate with the presser foot of the sewing machine; and

fig. 3 shows a cross section along the line III-III of fig. 1.

Detailed Description

Only the upper part and a piece of base plate of a sewing machine 1 are shown in fig. 1, the sewing machine 1 comprising a column 2 and an arm 3 extending at an angle to the column 2 in the horizontal direction. The arm 3 terminates in a head 4. The column 2, the arm 3, the head 4 and the base plate are enclosed by a housing 5 of the sewing machine 1. An arm shaft, not shown in the figures, is mounted for rotation in the arm 3. In the head 4, the arm shaft drives a needle bar, also not shown, which is mounted in the head 4 for axial displacement via a crank drive. The needle attached to the lower end of the needle bar can be moved up and down along a vertical axis 6 by means of a crank drive. The needle comprises an eye for guiding a needle thread supplied from a bobbin (not shown) for sewing together two pieces of fabric 7, 8 placed on top of each other.

When sewn together by the sewing machine 1, the fabrics 7, 8 are placed on a support plate 9 (see fig. 2). The support plate 9 has a pinhole (not shown).

A presser foot 10 is provided for clamping the fabrics 7, 8 during sewing. The presser foot 10 has a foot member 11 for applying pressure to the fabrics 7, 8 from above. The foot member 11 is fixed to the presser bar 13 by a screw 12. The presser bar 13 is guided in a guide sleeve 14 located in the head 4 along a presser bar axis 15 parallel to the needle bar axis 6.

A force source 16 configured as a leaf spring is used to provide pressure to enable the presser foot 10 to grip the fabric 7, 8 during sewing. In one aspect, the end portions 16a of the leaf spring 16 are supported on corresponding bearings (counterbearings) 17 mounted to the housing to enable the leaf spring 16 to pivot about a pivot axis 18. On the other hand, the end portion 16b of the leaf spring 16 bears on the free upper end 19 of the presser bar 13. The leaf spring 16 extends substantially horizontally in the arm 3.

In the region of contact with the leaf spring 16, the upper end 19 of the presser bar 13 is shaped approximately hemispherical, so that the leaf spring 16 can bear against the presser bar 13 in a defined manner.

The pre-stressing of the presser foot 10 by the leaf spring 16 is adjusted by means of an adjusting device 20 (see fig. 3). The adjustment device 20 has an adjustment body 21, which adjustment body 21 is mounted in the housing 5 so as to be rotatable or pivotable about an adjustment shaft 22 defining a pivot axis 23, the adjustment body 21 being connected to the adjustment shaft 22 so as to rotate together. The adjustment body 21 has an outer wall 24 defining an adjustment curve. In order to influence the preload force, the adjusting body 21-strictly speaking its outer wall 24-abuts the leaf spring 16 from above between its two

end portions

16a, 16b, as can be seen in fig. 2 and 3.

The radius R of the outer wall 24 varies continuously and strictly monotonically, as measured from the pivot axis 23, about the pivot axis 23 within the angular range of adjustment 25. In the embodiment shown in fig. 2 and 3, this occurs in a spiral.

The adjustment angle range 25 covers about 270. Depending on the design of the actuating body 21, other angular ranges of adjustment are also conceivable, in particular angular ranges of more than 180 °. When the outer wall of the adjustment body is helical, for example, the adjustment angle range can also be greater than 360 °.

The radius R of the outer wall 24 is at a minimum radius R within the adjustment angle range 25_minAnd a maximum radius R_maxTo change between. In the described embodiment, the ratio R_max/R_minAbout 3. Other ratios R are also contemplated according to various embodiments_max/R_minAnd in particular a ratio greater than 2.

The adjustment body 21 is actuated from outside the housing by means of an adjustment wheel 26. The adjustment wheel 26 is mechanically connected to the adjustment body 21 for pivoting the adjustment body 21 about the pivot axis 22. In the embodiment according to fig. 3, the adjustment wheel 26 is screwed to the adjustment shaft 22 by means of a central screw 27 extending coaxially with the adjustment shaft 22. The locking unit 28 enables the adjustment wheel 26 to be locked in a plurality of pivoting angle locking positions with respect to the housing 5. The locking unit 28 has a ball-shaped latching body 29. In fig. 3, the latch body 29 is forced to the right by a coil spring 30 supported on the bottom of a blind hole 31. The latch body 29 is prevented from falling out of the blind hole 31 due to the retaining sleeve 32 being mounted in the blind hole 32.

In the latched position of the locking unit 28 shown in fig. 3, the latching body 29 cooperates with a latching groove 33 in the adjustment wheel 26, which latching groove 33 is complementary to the latching body 29. Viewed in the circumferential direction about the pivot axis 23, the adjusting wheel 26 has a plurality of such latching grooves 33 which extend at equal intervals over the angular range of adjustment 25. The adjustment wheel 26 may, for example, be provided with two, three, four, five or tens, for example 50, such latching slots 33.

The preload force of the presser foot 10 is adjusted by the adjusting device 20 in the following manner: the operator looks up in the table the preload force to be set depending on the type and thickness of the fabrics 7, 8 to be sewn together. The preload force is assigned, for example, a value/number which is also provided on the adjusting wheel 26, strictly speaking in the region of the operator-facing side of the respective latching groove 33. The operator then turns the adjustment wheel 26 until the value is opposite an adjustment mark 34 (see fig. 1) on the housing 5 located adjacent to the adjustment wheel 26. During this time, the operator notices the intermediate latching position of the adjusting wheel 26, which is sensed by a separate click, in which the latching body 29 latches into or out of the respective latching groove 33. When the desired set preload force is reached, the latch body 29 engages the latching position 1 shown in fig. 3, so that the adjustment wheel 26 is locked in a predetermined position. At the predetermined location, the outer wall 24 is generally located at R_minAnd R_maxAgainst the leaf spring 16 and bends the leaf spring 16 to a predetermined extent, thereby preloading the leaf spring 16 to correspond to the preload force to be set, such that the presser bar 13 and thus the foot member 11 of the presser foot 10 apply a pressure to the fabric 7, 8 corresponding to the preload force currently set during sewing.

Claims

1. The sewing machine comprises

-a housing (5);

-a support plate (9);

-a presser foot (10) cooperating with the support plate (9) to clamp the fabric (7, 8);

-a force source (16) supported on the housing (5) on the one hand and on the presser foot (10) on the other hand, such that the presser foot (10) is preloaded against the support plate (9); and

-an adjustment device (20) for adjusting the preload force exerted on the presser foot (10) by the force source (16),

wherein,

-the adjustment device (20) comprises an adjustment body (21) mounted in the housing (5) so as to be pivotable about a pivot axis (23);

-wherein the adjustment body (21) comprises an outer wall (24),

via which outer wall the adjusting body (21) bears directly against the force source (16) for influencing the preload force, and

-the radius (R) of the outer wall varies monotonically between a minimum radius and a larger maximum radius over an angular range of adjustment (25) about the pivot axis (23);

-wherein the force source is a leaf spring (16), wherein

-a first end portion (16a) of the leaf spring (16) is clamped to be locked relative to the housing (5),

-a second end portion (16b) of the leaf spring abuts against an end of a presser bar (13) of the presser foot (10), the end of the presser bar being opposite to the foot member (11) of the presser foot (10), and

-between these two end portions (16a, 16b), the outer wall (24) of the adjustment body (21) directly abuts against the leaf spring (16).

2. Sewing machine as in claim 1, characterized in that the outer wall (24) of said adjustment body (21) is substantially helical within an adjustment angle range (25).

3. Sewing machine as in claim 1, characterized in that it comprises an adjustment wheel (26) arranged on the outside of the shell (5), which adjustment wheel (26) is mechanically connected to the adjustment body (21) for pivoting the adjustment body (21).

4. Sewing machine as in claim 3, characterized in that it comprises at least one locking unit (28) for locking the adjustment wheel (26) in at least two pivoting angle locking positions with respect to the housing (5).

5. Sewing machine as in claim 4, characterized in that the locking unit (28) is a latching unit with a preloaded latch body (29) cooperating with one of at least two latch grooves (33) in the latched position.

6. The sewing machine of claim 1, wherein the range of adjustment angles is greater than 180 °.

7. Sewing machine as in claim 6, characterized in that the adjustment angle range is 270 °.

8. Sewing machine as in claim 1, characterized in that the radius (R) of said outer wall (24) is at a minimum radius (R) within the adjustment angle range (25)_min) And maximum radius (R)_max) In which R is_max/R_min＞2。