JPH0729971Y2 - Sewing machine differential feed controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a differential feed control device for an overedge sewing machine, and more particularly to a differential feed control device that controls the ratio of the differential feed depending on the size of the main feed amount. Regarding the feed control device.

(Problems to be solved by the prior art and device) Overedge sewing machines including a vertically moving needle and a feeding device for moving cloth in cooperation with the needle are known. Further, an overedge sewing machine is known in which the feed device includes a differential feed mechanism having a main feed tooth and a sub feed tooth. In these, the ratio of the feed amount between the main feed dog and the sub feed dog (differential ratio) is adjusted for the cloth used and the sewing method, etc. The feed amount is from 1 mm to a maximum of 5 mm, and the differential ratio (main feed amount / sub feed amount) is 0.7.
Most of them are from 2.0 to 2.0.

The reason why the differential ratio is set to about 0.7 to 2.0 is because of the momentum limit dimension. As shown in FIG. 16, when the main feed amount is 5 mm, when the differential ratio is 2.0, the main feed dog M is closer to the operator side. The auxiliary feed tooth S arranged at the position is operated with a sub feed amount of 10 mm, and the main feed tooth M and the sub feed tooth S move the gap C at the phase moved to the feed direction side as shown by the dotted line in FIG. Each feed tooth locus and feed tooth shape are defined so as to keep. However, when determined in this way, the clearance CE formed between the main feed dog M and the sub feed dog becomes C + 5 mm when moved to the most operator side and the front side as shown by the solid line in FIG. At the same time, in order to make the effect of the auxiliary feed dog S on the cloth effective, the front position of the cloth presser F needs to be extended to the position P of the two-dot chain line in the figure.

In the sewing machine formed by extending the presser foot in this way,
Assuming that the main feed amount is 2 mm and the differential ratio is changed from 2.0 to 0.8, the sub-feed amount is 2 mm for the main feed amount of 2 mm as shown in FIG.
It becomes 1.6 mm, and the tip position of the auxiliary feed dog S moves to the cloth feed side by about 4.2 mm and reaches the frontmost position.

This position is closer to the cloth feed side than the tip of the cloth retainer, and even if the cloth is guided to the tip of the cloth retainer at the time of sewing, the cloth does not reach the auxiliary feed dog, so that the cloth is not fed.
Therefore, it is necessary to raise the cloth presser once to guide the cloth onto the feed dog and then lower the cloth presser again to grip the cloth.

On the other hand, depending on the type of fabric, there are those that have the property that the effect of shrink stitching is difficult to appear and those that do not show the effect of stretch stitching, and that require a differential ratio larger than the range of 0.7 to 2.0. There is. Therefore, as described above, there is little gap between the feed dogs, the frontmost position of the auxiliary feed dog is not largely changed, and a feed mechanism is provided which further expands the differential ratio with respect to the cloth in which the differential effect is hard to appear. With the goal.

Therefore, in the present invention, in the relation between the feed amount and the differential ratio, the differential ratio is 0.7 to 5 mm for the main feed amount of 1 to 5 mm.
Although the value of 2.0 has been described, generally the main feed amount is 5
Since a combination with a differential ratio of 2.0 in millimeters rarely occurs, the above object is to be achieved by decreasing the maximum differential ratio in response to an increase in the main feed amount.

(Means for Solving the Problem) Therefore, in the present invention, a needle which is connected to a main shaft connected to a drive source via a transmission means and moves up and down, and a main feed dog are fixed to adjust the needle up and down. A main feed drive means connected to the main shaft, a sub feed drive means for fixing a sub feed tooth and connecting the sub feed drive means, a feed adjusting means for setting a feed amount of the main feed tooth, and the main feed tooth In the sewing machine including the differential ratio adjusting means for setting the feed amount of the auxiliary feed tooth with respect to the feed amount of the feed amount, the feed adjusting means displays a display portion for displaying the feed amount and a cam outer diameter corresponding to the feed amount. A manually operable cam portion to be formed, a display portion for displaying a feed amount corresponding to a selected cam outer diameter of the cam portion, and a feed portion in which one end contacts and follows the cam portion and the other end is connected to the feed driving means. Transmission means, the actuation adjusting means corresponds to the differential ratio A manually operable cam portion that forms the outer diameter of the cam, a display portion that displays a differential ratio corresponding to the selection of the outer diameter of the cam portion of the cam portion, and one end of which follows the cam portion and the other end of which is the difference. A differential ratio transmitting means connected to the dynamic ratio adjusting means, and a connecting arm connecting to the cam portion of the feed adjusting means limits the maximum manually operable differential ratio of the cam portion of the differential adjusting means. Link.

(Example) Next, the Example of this invention is described in detail with reference to drawings.

FIG. 12 is an external view of an overlock sewing machine incorporating the limited feed device of the present invention, which will be described with reference to FIG. 11 which is a mechanism explanatory view. A main shaft 2 is rotatably supported on the sewing machine frame 1, and the main shaft is connected to a sewing machine motor (not shown) fixed to the sewing machine frame 1 via a transmission means.

A needle bar 3 has a needle 4 fixed to the tip thereof, and is supported by the sewing machine frame 1 so as to be vertically movable from the lower side in the feeding direction to the upper side on the side facing the feeding direction. The needle bar is connected to the main shaft 2 via a connecting means, and the main shaft 2 is rotated by the rotation of the sewing machine motor, and then the needle bar 3 is vertically moved. A needle plate 6 is fixed to the sewing machine frame 1 and has a needle hole 6a in which the needle 4 can be retracted and a feed dog groove 6b in which the feed dog 5 can be retracted. A looper (not shown) that is driven in synchronization with the vertical movement of the needle is arranged below the needle plate, and is connected to the main shaft via a looper driving means (not shown). .

The feed dog 5 cooperates with the cloth presser 7 to hold the work cloth and transfer the work cloth from the front side toward the operator side to the opposite side. In the present embodiment, the feed dog 5 is located on the side opposite to the needle drop point of the needle 4. 5a,
The auxiliary feed dog 5b is arranged in front of the operator.

Next, a feeding mechanism for feeding the feed dog 5 will be described with reference to FIG.

A vertical feed cam 8 is fitted and fixed to the main shaft 2, and a vertical feed angle sesame 9 is rotatably fitted to the outer diameter cam portion.

Reference numeral 10 denotes a main feed table, which has the main feed dog 5a fixed to one end thereof and a bifurcated groove formed below and fitted into the vertical feed angle sesame 9. Reference numeral 11 denotes a sub-feeding base, which has the sub-feeding tooth 5b fixed to one end thereof and has a bifurcated groove formed below and fitted into the vertical feeding angular sesame 9.

Reference numeral 12 denotes a horizontal feed cam which is fitted and fixed to the main shaft 2, and a feed rod 13 is attached to the outer diameter of the eccentric cam portion of the horizontal feed cam.
One end of is rotatably fitted. A main feed rod pin 14 is fixed to the other end of the feed rod, and one end of a main feed link 15 is rotatably fitted to the main feed rod pin.

Reference numeral 16 denotes a feed shaft, which is supported by the sewing machine frame 1 in parallel with the main shaft 2, and a main feed arm 17 is fitted on the feed shaft so that the axial movement of the main feed arm 17 is restricted and only the rotational direction is possible. A pin 18 is fixed to one end of the main feed arm, and the other end of the main feed link 15 is fitted to the pin.

The other end of the main feed arm 17 is fitted to a main feed pin 19 fixed to the main feed base 10 on the feed direction side from the fixed position of the main feed teeth.

A main feed adjusting arm 20 is rotatably fitted to the main feed adjusting shaft 21 supported by the sewing machine frame 1 in parallel with the main shaft 2. A main feed adjusting arm pin 22 is fixed to one end of an arm portion of the main feed adjusting arm 20, and one end of a main adjusting link 23 is rotatably fitted to the main feed adjusting arm pin. The other end of the main adjusting link is rotatably fitted to the main feed rod pin 14.

A sub-feed connecting pin 24 is rotatably fitted to the other end of the main feed arm 17, and a feed transmission link is attached to the sub-feed connecting pin.
One end of 25 is rotatably fitted.

A sub-feed arm 26 is rotatably fitted to the feed shaft 16 and has a sub-feed arm pin 27 fixed to one end thereof. One end of the sub-feed operation link 28 is fitted to the sub-feed arm pin, and the other end of the sub-feed operation link is fixed to the feeding direction side from the fixing position of the sub-feed tooth 5b of the sub-feed base 11. It is fitted on the auxiliary feed pin pin 29 of.

Secondary feed link arm operation pin fixed to the other end of the secondary feed arm 26
One end of the auxiliary feed link 31 is rotatably fitted to the 30.
The other end of the sub feed link is rotatably fitted to a sub feed pin 32 fixed to the other end of the feed transmission link 25.

A sub-feed adjusting arm 33 is rotatably fitted to the sub-feed adjusting shaft 34 supported by the sewing machine frame 1 in parallel with the main shaft 2. A sub-feed adjusting arm pin 35 is fixed to one end of the arm portion of the sub-feed adjusting arm 33, and one end of a sub-adjustment link 36 is rotatably fitted to the sub-feed adjusting arm pin. The other end of the sub adjustment link is rotatably fitted to the sub feed pin 32.

The adjustment of the feed amount of the main feed dog 5a in the differential feed mechanism as described above will be described with reference to FIGS. 3 and 4.

FIG. 3 shows the state in which the feed amount of the main feed dog 5a and the minimum a1 are set, and the main feed adjusting arm 20 is rotated in the most counterclockwise direction about the main feed adjusting shaft 21. Therefore, the main feed adjusting arm pin 22 fixed to the tip of the main feed adjusting arm 20 is set at the lowest point A.

In the figure, the arrow E direction indicates the cloth transfer direction. In the figure, the solid line is the feed end position and the dotted line is the feed start position. At the point A of the main feed adjusting arm pin 22, when the main shaft 2 rotates, the feed rod 13 operates in the range between the dotted line and the solid line, and the main feed rod pin 14 fixed to the tip of the feed rod has a point at the start of feeding. The position of point b at the end of feeding at the position of
The main feed pin 19 fixed to the tip of the main feed dog 5a moves a1 by moving a1 during one rotation of the main shaft 2.

FIG. 4 shows a state in which the feed amount of the main feed dog 5a and the maximum a2 are set, and the main feed adjusting arm 20 is at the position rotated most clockwise around the main feed adjusting arm, The main feed arm pin 22 fixed to the tip of the main feed adjustment arm 20 is set at the uppermost point B.

When the main shaft 2 rotates in the state set at the point B, the feed rod 13 operates in the range between the dotted line and the solid line, and the main feed rod pin 14 fixed to the tip of the feed rod is at the position of point e at the start of feeding. At the end of feeding, the position is point f, and the main feed pin 19 fixed to the tip of the main feed arm 17 moves a2 during one rotation of the main shaft 2 so that the main feed dog 5a fixed to the main feed 10 is moved. Move a2.

Next, adjustment of the feed amount of the auxiliary feed dog 5b will be described.
The feed amount of the auxiliary feed dog adjusts a differential mechanism that increases or decreases the movement for the main feed dog 5a.

FIG. 5 shows a state in which the minimum differential ratio is set. The sub-feed adjusting arm 33 is at the most counterclockwise position, and the sub-feed is fixed to the tip of the sub-feed adjusting arm. The adjustment arm pin 35 is set at the lowest point C.

At the point C, the main feed arm 17 is rotated by the rotation of the main shaft 2.
Operates in the range between the position indicated by the dotted line and the position indicated by the solid line, and the auxiliary feed link pin 32 fixed to the tip of the feed transmission link 25 is at the position g at the start of the feed and at the position h at the end of the feed. The auxiliary feed arm pin 27 fixed to the tip of the feed arm 26 moves by d1 during one rotation of the main shaft to move the fixed auxiliary feed tooth 5b to the auxiliary feed base 11 by d1.

FIG. 6 shows a case in which the maximum differential ratio is set. The sub-feed adjusting arm 33 is at the most clockwise position and the sub-feed adjusting arm fixed to the tip of the sub-feed adjusting arm. The pin 35 is set at the uppermost point D.

At the point D, the main feed arm 17 is rotated by the rotation of the main shaft.
Operates in the range between the position indicated by the dotted line and the position indicated by the solid line, and the auxiliary feed link pin 32 fixed to the tip of the feed transmission link 25 becomes the position i at the start of feeding and the position j at the end of feeding, The auxiliary feed arm pin 27 fixed to the tip of the feed arm 26 moves d2 during one rotation of the main shaft 2 to move the fixed auxiliary feed tooth 5b to the auxiliary feed base 11 by d2.

As described above, the main feed amount of the main feed dog 5a is controlled by the rotational position of the main feed adjusting arm 20, and the sub feed amount of the sub feed dog 5b with respect to the main feed amount becomes a differential amount, which is the sub feed amount. It is controlled by the rotational position of the adjusting arm 33.

Next, the adjusting portion for the main feed amount and the differential feed amount will be described with reference to FIG. 37 is a feed dial shaft having a feed adjusting dial 38 having a number indicating the feed amount stamped on one end, and a feed adjusting cam 39 inserted and fixed to the base plate.
It is rotatably supported by 40. The feed adjusting cam 39 is formed with a gum outer diameter 39a that is eccentric with respect to the feed dial shaft 37, and a rotation groove 39b is formed on the base plate 40 side to limit the rotation amount thereof.

Reference numeral 41 is a feed transmission arm, which is fixed to the base plate 40 at one end so as to be parallel to the feed dial shaft 37.
It is fitted to be rotatable. An engagement pin 43 is provided at one end of the feed transmission arm 41 so as to be adjustable in the axial direction, and a tip end 43a of the feed transmission arm 41 is always provided with a spring means (not shown) so that the feed adjustment cam 39 has a cam outer diameter 39a. Is in contact with.

A pin 44 is fixed to the other end of the feed transmission arm 41.
One end of a feed adjusting rod 46 rotatably fitted to a pin 45 fixed to one end of the main feed adjusting arm 20 is fixed, and the other end of the feed adjusting rod is rotatably fitted to the pin 44. Are linked together.

Reference numeral 47 denotes a differential dial shaft, which is fixed at one end thereof with a differential adjustment dial 48 having a mark indicating a differential ratio which is a ratio of the feed amount of the main feed dog to the feed amount of the main feed tooth. The dynamic dial shaft has a differential adjustment cam 49 inserted and fixed therein, and is rotatably supported by the base plate 40.

The differential adjustment cam 49 is formed with a cam outer diameter 49a that is eccentric with respect to the differential dial shaft 48, and a rotation groove 49b for limiting the amount of rotation is formed on the end surface of the base plate 40 side. There is.

A differential transmission arm 50 has a differential adjustment pin 51 fixed at one end to the base plate 40 so as to be parallel to the differential dial shaft 48.
It is fitted to be rotatable. An engaging pin 52 is arranged at one end of the differential transmission arm 50 so as to be adjustable in the axial direction, and the tip 52a is always provided outside the cam of the differential adjustment cam 49 by a spring means (not shown). It is in contact with the diameter 49a.

A pin 53 is fixed to the other end of the differential transmission arm 50.

One end of a differential adjustment rod 55 is rotatably fitted to a pin 54 fixed to one end of the auxiliary feed adjustment arm 33, and the other end of the differential adjustment rod is rotatably fitted to the pin 53. Are connected.

Reference numeral 56 is a limiting rod, and pins 56a and 56b are planted at both ends, respectively, and two grooves 40 are provided on the base plate 40.
It is inserted in a and 40b, and is fitted in the rotation groove 39b of the feed adjustment cam 39 and the rotation groove 49b of the differential adjustment cam 49, respectively.

The base plate 40 is fixed to the sewing machine frame 1, and the display mark A for aligning the scale of the feed adjusting dial 38 and the scale of the differential adjusting dial 48 are aligned on the base plate 40. A display mark B (not shown) is provided for this purpose.

Next, regarding the operation of the adjusting portion constructed in this way,
It will be described with reference to FIGS.

In the figure, the groove 40a is provided on an arc centered on the feed dial shaft 37, and the groove 40b is provided on an arc centered on the differential dial shaft 47.

FIGS. 7 and 8 show a state in which the maximum feed amount is set to 5 mm in this embodiment, and the feed adjustment dial 38 is used.
Is rotated counterclockwise. When the feed adjusting dial is rotated about the feed dial shaft 37,
The rib portion 38c of the rotation groove 39b of the feed adjusting dial 38 contacts the tip 56a of the limiting rod 56.

Further, when the feed adjusting dial 38 is rotated counterclockwise, the tip end 56a of the limiting rod 56 comes into contact with the upper end of the groove 40a of the base plate 40 to reach the upper limit feed set value of 5 mm. At this time, the maximum diameter portion of the cam outer diameter 39a of the feed adjusting cam 39 contacts the tip of the engagement pin 43 fixed to the feed transmitting arm 41, and the feed transmitting arm 41 rotates about the feed adjusting pin 42. Then, the feed adjusting rod 46 is pulled up to the uppermost position and the main feed adjusting arm 20 is rotated clockwise in FIG. 1 to set the position in FIG. 4 to the maximum feed amount of 5 mm.

When the rib portion 38c of the rotary groove 38b pulls up the limiting rod 56 along the arcuate groove 40a by the rotation of the feed adjusting cam 39, the other end 56b of the limiting rod 56 is moved to the differential adjusting cam 4
The differential adjusting cam 49 is rotated clockwise as shown by the dotted line in FIG.
Is set as the maximum differential ratio.

Therefore, when the maximum feed amount is 5 mm, the differential adjustment cam
49, adjustment in the direction of the dotted line in the figure, that is, in the direction of making the differential ratio smaller than 1: 1.4 is allowed. 40c and 40d in the figure
Is a stopper pin planted in the base plate, is located in the circumferential groove of the feed adjusting cam 39, rotates the feed adjusting dial 38 clockwise, and displays the minimum feed amount as the display mark. When they match each other, they come into contact with the rib 39c.

In the figure, 40d is adapted to contact the rib 49c when the differential adjustment dial 48 is rotated clockwise and the minimum differential display matches the display mark.

Next, when the feed amount display 4 mm of the feed adjusting dial 38 is rotated to match the display mark, the feed adjusting cam 39 is rotated clockwise in FIG. 8 to contact the engaging pin 43. The outer diameter 39a is moved from the maximum diameter portion with a feed amount of 5 mm to the diameter portion with a feed amount of 4 mm, the feed transmission arm 41 is rotated counterclockwise, and the feed adjustment rod is pushed down to adjust the main feed adjustment. The arm 20 is rotated counterclockwise to reduce the feed amount from 5 mm to 4 mm.

In FIG. 8, the rotation of the feed adjusting cam 39 in the clockwise direction causes the limiting rod 56 to move to the lower position and the limiting pin 56b.
Descends in the circular arc groove 40b.

Therefore, the rib 49c of the differential adjustment cam 49 and the limiting pin 5
A counterclockwise rotation gap occurs between 6b.

Since this rotation clearance allows the counterclockwise rotation of the differential adjustment dial 48, when the differential adjustment dial is rotated, the differential adjustment cam 49 is engaged with the cam outer diameter a and the position on the large diameter side. The pin 52 abuts and rotates the differential transmission arm 50 clockwise. The rotation lowers the differential adjusting rod 55 to rotate the sub-feed adjusting arm 33 clockwise in FIG. 1 to increase the differential ratio.

Although the example in which the adjustment amount of the differential ratio is limited by the setting of the feed amount has been described above, the upper limit value of the feed amount is similarly limited by the setting of the adjustment amount of the differential ratio.

That is, as shown in FIGS. 7 and 8, when the feed amount of the feed adjusting dial 38 is set to 5 mm and the differential ratio of the differential adjusting dial 48 is set to 1: 1.4, a desired differential ratio, for example, 1 :. When adjusting to 4, the differential adjustment dial 48 is rotated so as to match the differential ratio 1: 4 display of the differential adjustment dial 48, and the differential adjustment cam 4
Rotate 9 counterclockwise in Fig. 8.

The rib 49c of the differential adjustment cam 49 is the pin 5 of the limiting rod 56.
It comes in contact with 6b and is pushed down to the position shown in Fig. 10.

By the lowering of the limiting rod 56, the pin 56a at the other end abuts against the rib 39c of the feed adjusting cam 39 and pushes it down to rotate the feed adjusting cam 39 clockwise.

As a result, the display of the feed adjusting dial 38 is set to 1.5 mm, and the feed transmitting arm 41 is attached to the small diameter portion of the feed adjusting cam 39.
The engaging pin 43 fixedly attached to the feed transmitting arm 41
Rotates counterclockwise. The feed adjusting rod 46 is pushed down by the rotation of the feed transmitting arm to move the main feed adjusting arm 20.
Rotate counterclockwise to set the feed amount of the main feed dog as small as 1.5 mm.

In the present invention, the main feed amount setting unit and the differential ratio setting unit are separately configured with respect to the portion that associates the differential range between the feed adjustment dial 38 and the differential adjustment dial 48. , The relationship between the main feed amount and the set value of the maximum differential ratio is a in FIG. 13, b in FIG. 14 and c in FIG.
It is also possible to set it at will at the time of production as described above.

That is, in the figure, the horizontal axis represents the feed amount and the vertical axis represents the maximum differential ratio.

(Effect) As described above, according to the present invention, the maximum value of the differential ratio can be set to an arbitrary value in advance so as to correspond to the feed amount. It is possible to set an unnecessary upper limit condition such as a large differential ratio at the time of a large feed amount, and set a small differential ratio at the time of a large feed amount and a large differential ratio at the time of a small feed amount. Sewing conditions can be set.

[Brief description of drawings]

1 to 15 relate to an embodiment of the present invention, FIG. 1 is an explanatory view of a feed mechanism, FIG. 2 is an explanatory view of a feed adjusting operation portion, and FIG. 3 is a view when a feed amount is set to a minimum. Of the main feed mechanism of FIG. 4, FIG. 4 is an operation diagram of the feed mechanism when the feed amount is set to the maximum, and FIG. 5 is an operation diagram of the sub feed mechanism when the differential ratio is set to the minimum. , FIG. 6 is a diagram for explaining the operation of the auxiliary feed mechanism when the differential ratio is set to the maximum, and FIG. 7 is a relationship between the feed adjustment dial and the differential adjustment dial when the feed adjustment dial is set to the maximum feed amount. Explanatory drawing, FIG. 8 is a partial cross-sectional view explaining the interlocking state of the feed adjusting dial and the differential adjusting dial when the maximum feed amount is also set, and FIG. 9 is setting the differential dial to the maximum differential ratio. Fig. 10 is an explanatory view of the relationship between the feed adjustment dial and the differential adjustment dial, and Fig. 10 shows the feed adjustment when the maximum differential ratio is set. Partial cross-sectional view explaining the interlocking state of the joint dial and the differential adjustment dial, Fig. 11 is an explanatory view of the mechanism of the sewing machine, Fig. 12 is an external view of the sewing machine, and Fig. 13 is the feed amount and maximum differential ratio setting. FIG. 14 is a diagram showing an example of the state, FIG. 14 is an embodiment showing the example of the feed amount and the maximum differential ratio setting state, FIG. 15 is an example showing the state of the feed amount and the maximum differential ratio setting state, and FIG. Fig. 17 is an explanatory view of the feed dog position when the feed amount is 5 mm and the differential ratio is 1: 2 in the conventional sewing machine. Fig. 17 shows the feed amount of 2 mm and the differential ratio is 1: 0.8.
Is a feed dog position explanatory view at the time of, 2 is a spindle, 4 is a needle, 5a
Is a main feed dog and 5b is a sub feed dog.

Claims (1)

[Scope of utility model registration request] 1. A main feed drive means connected to a main shaft connected to a drive source via a transmission means and moving up and down, and a main feed tooth fixedly connected to the main shaft so as to be synchronized with the vertical movement of the needle. A sub-feed driving means for fixing the sub-feed tooth to the main-feed driving means, a feed adjusting means for setting a feed amount of the main-feed tooth, and a sub-feed for the feed amount of the main-feed tooth. In a sewing machine provided with a differential ratio adjusting means for setting a feed amount of teeth, the feed adjusting means includes a display portion for displaying the feed amount and a manually operable cam portion for forming a cam outer diameter corresponding to the feed amount. A display unit for selectively displaying a feed amount corresponding to the cam outer diameter of the cam unit, and a feed transmission unit having one end abutting and following the cam unit and the other end connected to the feed drive unit,
The differential ratio adjusting means includes a manually operable cam portion that forms a cam outer diameter corresponding to the differential ratio, a display portion that displays the corresponding differential ratio when the cam outer diameter of the cam portion is selected, and one end of the display portion. A differential ratio transmitting means for contacting and following the cam portion and the other end connected to the differential ratio adjusting means, and a connecting arm connected to the cam portion of the feed adjusting means is formed by the cam portion of the differential adjusting means. A differential feed control device for a sewing machine, which is connected so as to limit a set maximum differential ratio to a maximum differential ratio related to a feed amount.