JPH0336556B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a workpiece feeding device that includes at least one workpiece feed dog and a pressing foot piece that are provided below the workpiece and perform intermittent feeding. the workpiece on the holding plate is guided with its edge along the contact edge, and a rotating device provided above the workpiece is able to rotate the workpiece about an axis coincident with the needle;
The present invention relates to a sewing machine having a feeding device and a rotating device for a workpiece to be sewn.

[Prior Art] In such a sewing machine, which is known from German Patent No. 1 685 079, the edge of the workpiece tends to move towards the contact edge due to the rotational moment generated by the feed of the feed dog in the area that is still to be sewn. Being pushed. In order to be able to form stitches also in corners, for example at the tips of shirt collars, a rotating device is provided which can be placed on the workpiece from above and rotates the workpiece through the required angle about the axis of the needle. Such devices require special drive motors and are therefore very expensive. This rotating device is not suitable for use in forming curved seams that change direction from stitch to stitch. This is because, at a predetermined sewing speed, it is not taken into account that the rotating device is released within the stab timing and then placed again for operation. Furthermore, there is a risk that the work piece made of soft material will be deformed.

In the workpiece guiding device for a sewing machine known from German Patent No. 1 485 331, the edges of the workpiece are folded back. At least one nozzle is provided to ensure that the workpiece is always in contact with the contact edge in this folding direction. An air jet emanating from each nozzle presses the workpiece against the contact edge at right angles to the sewing direction. Furthermore, an air nozzle is provided which also acts in the sewing direction to offset the frictional forces occurring in the folding direction.

[Problem to be solved by the invention]

The problem on which the invention is based is that it is possible to sew workpieces made of soft materials automatically with arcuate or acute-angled seams parallel to the edge of the workpiece. It is to configure the sewing machine.

[Means to solve the problem]

In order to solve this problem, according to the present invention, the rotating device has at least one concentric part with respect to the needle passage hole.
It has a plurality of air nozzles distributed over a partial circle and oriented tangentially to this partial circle and at an acute angle to the plane of the holding plate, capable of upward and downward movements via the upper axis. An elevating transmission device is provided which separates the pressing leg from the workpiece at the timing of the needle piercing, and while the needle is moving downward until it pierces the workpiece and reaches approximately the bottom dead center.
Release the pressing foot piece from the workpiece.

〔Effect of the invention〕

According to the present invention, while the needle is being pierced into the workpiece, the pressing leg is separated from the workpiece by the lifting transmission device, so that the workpiece is not subjected to the frictional force caused by the pressing of the pressing foot, and is not pierced. The needle is precisely positioned by the needle, and the air flow from the plurality of air nozzles provided on a partial circle around the needle passage hole ensures that the needle is pressed onto the holding plate and reliably follows the contact edge. Fully freely rotatable around the axis of the needle. Thus, according to the invention:
Even when sewing particularly strongly curved or acutely angled seams, the workpiece is guided precisely along the contact edge, regardless of how many stitches the curved seam extends.

〔Example〕

Further advantages and features of the invention will become apparent from the following description of an embodiment of the invention with reference to the drawings.

The sewing machine 1 has a lower arm whose upper surface is configured as a base plate 2, and this lower arm is fitted on a base plate 3. The substrate 2, which serves as a holding plate for the workpiece, includes:
An upper arm 4, which is hollow and therefore constructed in the manner of a housing, is mounted in the usual manner, in which an upper shaft 5 is rotatably supported, having a flywheel 6 at one end, the upper shaft 5 being free. The end ends in a conventional crank mechanism (not shown), which serves to drive the needle bar 7 with the needle 8. A pressing rod 9 is further supported on the upper arm 4 so as to be movable up and down, and a pressing leg 10 is screwed to the lower end of this pressing rod (FIG. 2). The pressure foot 10 is formed with a groove 12 in which a deflection roller 11 and a toothed belt 13 are accommodated. A pressure spring 14 surrounding the pressure bar 9 rests on the one hand on the upper arm 4 via a washer 15 and on the other hand on a support piece 16 which is attached to the pressure bar 9 with a set screw 17. Support piece 16
The free end of the pull rod 18, which is pivotally connected to the pull rod 18, is rotatably and adjustably held and guided in the elongated hole 20 of the lever 21 by means of a set screw 19. This elongated hole is located at the rising height a of the pressing leg piece 10 (Fig. 5b).
and thus to adapt to the different compressibility of different workpieces. The lever 21 is attached to a shaft 22, which is rotatably supported by the upper arm 4. One end of a lever 24 is adjustably mounted on this shaft 22 by a tightening coupling piece 23.
Roller 2 rotatably supported via pin 26
A notch 25 for accommodating the lever 24 is provided in this lever 24. The roller 27 is in contact with a cam 28 mounted on the upper shaft 5 so that its angle can be adjusted. The lever 24 has its free end, ie the clamping coupling piece 23
It has a contact surface 30 at the opposite end. A unidirectionally acting pneumatic operating cylinder 31 is attached to the upper arm 4 by means of a screw 32, the piston rod 33 of which extends into the upper arm 4 above the upper shaft 5 and engages the contact surface 30 of the lever 24. can do. The above-mentioned portions 16 to 28 constitute a lifting transmission device H that raises and lowers the press rod 9 by rotation of the upper shaft 5. A height adjustment of the support piece 16 on the pressure bar 9 or a similar adjustment at the clamping connection piece 23 makes it possible to adapt the pressure foot 10 to different thicknesses of the workpiece.

A shaft 36 extending parallel to the upper shaft 5 is rotatably supported by the bearings 34 and 35 in the upper arm 4 (FIG. 1), and one end of the shaft 36 is provided with a bearing having a trigon structure on the side. It has entered a ratchet (not shown). Such an arrangement is known, for example, from German Patent Application No. 3008135, which corresponds to U.S. Pat. No. 4,271,776. This ratchet is connected to a crank 37. The shaft 36 is fixed in the axial direction by a retaining ring 38 on the side of the bearing 34, and the other end near the pressing leg 10 is connected to a gear 39 so as not to rotate relative to it (FIG. 2). toothed belt 13
is being passed around. A swing lever 4 is mounted on the shaft 36.
0 is supported for relative rotation and has a cap 41 that covers the gear 39 and a lever 42 that extends radially downward. A screw 43 is attached to the lower end of the lever 42.
A turning piece 44 for the toothed belt 13 is attached. The connecting rod 45 is swingably attached to the lever 42 and the pressing rod 9 by screws 46 at both ends thereof.

As can be seen in FIG. 1, a conventional stitch length adjustment transmission 47 is provided in the upper arm 4 and is connected via a pull rod 48 to a crank 49. Bearing 5 in the lower arm, which is also hollow
A crank 4 is mounted on a feed shaft 52 supported by
9 is mounted so as not to rotate relative to each other, and another crank 53 is also fixed on this feed shaft 52 so as not to rotate relative to each other. The cranks 53 and 37 are connected to each other via a pull rod 54. The feed shaft 52 is equipped with a U-shaped piece 55 for feeding, and this U-shaped piece 55 is connected to the feed beam 5 via a pin (not shown).
6. This feed beam 56 is supported via a crank (not shown) on an eccentric pin of a shaft (not shown) supported in the lower arm, and this shaft is connected to the upper shaft 5 through a toothed belt 57. ing. A feed dog 58 is provided on the feed beam 56 in the area of the needle 8 (see FIGS. 3 and 4).
figure). Throat plate 6 attached to base plate 2 with screws 59
2 is a notch 60 for the feed dog 58 and a needle passage hole 61
and are formed. Plate stopper 63 for work piece
is formed with a contact edge 64 and a long hole 65, and has a screw 66.
Since the contact edge 64 is adjustably attached to the base plate 2, the distance between the contact edge 64 and the needle passage hole 61, and thus the distance between the seam and the edge of the workpiece, can be adjusted. The contact edge 64 is generally straight-shaped and extends parallel to the direction of feed of the feed dog 58 . Furthermore, the contact edge 64 extends on both sides of the straight line passing through the needle passage hole 61 at right angles to the feed direction, so that the edge of the workpiece can always be guided in contact with the contact edge 64.

As can be seen from FIG. 1, the bearing 67 is mounted on the board 2.
is attached, and a double-acting pneumatic cylinder 68 is swingably supported on this bearing 67. The piston rod 69 of the operating cylinder 68 is pivotally connected to a lever 71 supported by a bearing 70 on the base plate 2 and is connected to a hollow plate 7 configured semicircularly and having a compressed air connection 73.
2 (FIG. 6) is provided on this lever 71. As shown in FIG. 7, the hollow plate 72 has an upper plate 74.
and a lower plate 75 parallel to this, and these upper plates 7
4 and the lower plate 75 are connected to each other via a sealing piece 76 and a stud 77. The compressed air connection 73 on the top plate 74 has a connecting piece 78 for fitting a hose 79. The upper plate 74 and the lower plate 75 are
Together with the sealing piece 76, a flat compressed air distribution space 80 is defined.

The lower plate 75 has a plurality of air nozzles 81 arranged at an acute angle of 30 to 60 degrees with respect to the plate surface, and these air nozzles 81 are connected to the needles 8, that is, the needle passage holes 6.
are arranged on concentric partial circles 82, 83 extending over approximately 180° with respect to 1, respectively;
83. The air nozzle 81 is directed to press the connecting edge of the workpiece W, that is, the edge that is not yet sewn, against the contact edge 64 of the plate-shaped stopper 63.

According to FIG. 2, two reflective photoelectric devices 85, 86 are provided on the plate 84 of the upper arm 4 of the sewing machine 1, and by these photoelectric devices 85, 86 the opening/closing point 8 is
7, 88 (FIG. 3) are formed.

The operation of this sewing machine is as follows.

Before the operation starts, the needle 8 of the sewing machine 1 is at the highest position, and the pressing foot 1 is moved by operating the operation cylinder 31.
0 is in the raised position and the operating cylinder 68
Assume that the hollow plate 72 is in the raised position shown by the chain line in FIG. 1 by the operation. By operating the operating cylinder 31, i.e. by pushing out its piston rod 33,
The engagement between the piston rod 33 and the contact surface 30 causes the lever 24 to pivot about the shaft 22, thereby causing the lever 21 to pivot at the same time. The upward swing of the lever 21 is transmitted via the tension rod 18 to the support piece 16, which causes the pressure rod 9 to rise against the force of the pressure spring 14, so that the pressure foot 10 is separated from the throat plate 62. No more contact. During the upward movement of the pressure rod 9, the lever 42 and the deflection piece 44 are also swung away from the pressure rod 9 via the connecting rod 45, so that the toothed belt 13, which is designed as an upper feed piece for the work piece, is swung away from the pressure rod 9. is kept in tension. By operating the operating cylinder 31, the roller 27 also moves the cam 2 at the same time.
8 away from the range of action.

Now, as an example, a workpiece W shown in the form of a shirt cuff in FIG.
If there is a stopper 63, the outer edge of the work piece W
is applied to the contact edge 64 of. As can be seen from FIG. 3, the inserted workpiece W has a reflection photoelectric device 85,
86, the optoelectronic devices 85, 86 generate a signal which confirms the presence of the work piece. Sewing machine 1 can now be started.

After operating the start button (not shown) on the control device,
First, the pneumatic cylinders 31 and 68 are switched, so that the pressure foot 10 is lowered onto the workpiece W and the hollow plate 72 is lowered into a lower position directly above the workpiece W, in which position it is lowered. The hollow plate 72 has not yet contacted the workpiece W. When the upper shaft 5 rotates, a oscillating movement is carried out in the seam adjustment transmission 47, and the shaft 36 and therefore the toothed belt 13 as the upper feed piece are moved intermittently by a ratchet provided on the crank 37.

At the same time, the feed dog 58 performs a feed movement, so that the work piece W is fed in the direction of the arrow 89. When the tip of the needle 8 begins to pierce the workpiece W as shown in FIG. 5b, the operating crest 28' of the cam 28 comes into contact with the roller 27 of the lever 24, thereby causing the lever 24 to swing. Via the lever 21, the pressure rod 9 and thus the pressure foot 10 are moved away from the workpiece W by a small distance corresponding to the lifting height a. At the same time, feed dog 58
is separated from the workpiece W. At the same time, feed dog 58
is located below the mounting surface of the work piece W, that is, below the throat plate 62. The workpiece W, which is now free of any frictional forces from the toothed belt 13 or the feed dog 58 forming the workpiece feed piece, can therefore be easily aligned against the contact edge 64 of the stop 63. During the subsequent formation of the stitch, the needle 8 performs a downward stroke to its lowest position and thus to its bottom dead center. When the needle 8 reaches the bottom dead center during its downward movement,
By appropriately forming the operation peak 28' of the cam 28, the pressing foot piece 10 descends again onto the work piece W, so that during the formation of the system loop gripped by the inner hook G (the 5th c.
), the workpiece W is fixedly held on the throat plate 62. The pressing leg 10 that holds the upper feeding piece, that is, the toothed belt 13 that circulates at the same time, also plays the role of holding down the workpiece W at this moment. During the subsequent stitch formation, the needle 8 is raised. After the needle 8 leaves the workpiece W, the workpiece W is fed again.

Due to its own weight, the work piece W rests on the substrate 2 or the base plate 3 even outside the seam forming area, and is located in a range substantially on the other side of the needle passage hole 61 or the needle 8 when viewed from the contact edge 64. Due to the feed motion in the sewing direction 89 forced on the workpiece W by the feed dog 58 and the toothed belt 13, a rotational moment acting on the workpiece W is generated around the center of gravity of the workpiece W, and the sewing is performed. Needle passage hole 61 when viewed in growth direction 89
The edge of the workpiece W in front of is pressed against the contact edge 64. The workpiece edge of the workpiece W in the region that is not yet sewn is therefore always turned towards the contact edge 64. In FIG. 4, this rotational moment acts counterclockwise. This rotational movement resulting from the feeding in the sewing direction 89 is facilitated because the pressure foot 10 is always kept away from the workpiece W during a part of the raising and lowering stroke of the needle 8. The force for guiding the edge of the workpiece W along the contact edge 64 of the stopper 63 in this manner is sufficient to guide a workpiece W having a relatively gentle convex or concave arc. However, this is of course insufficient for guiding strongly curved arcs. Processing piece W in a strongly curved arc range such as the tip of a collar
The aforementioned hollow plate 72 is used to guide the reflection optoelectronic devices 85, 86 and is controlled via a control device.

In other words, the workpiece W is at the initial position A as shown in FIG.
When the workpiece W leaves the first opening/closing point 88, the seam, which had been straight until then, transitions into a strongly curved arc, and in this arc the workpiece W leaves the first opening/closing point 88
A photoelectric device 85 generates a signal indicating the absence of a workpiece at the opening/closing point 88 . Since then, hose 7
Compressed air is supplied to the hollow plate 72 via 9,
A compressed air distribution space 80 is reached. air nozzle 81
Due to the above-mentioned arrangement, the work piece W has an arrow 90
Since a rotational moment is applied in the direction shown in FIG. 6, the work piece W is guided in contact with the contact edge 64 of the stopper 63 for each stitch even when forming subsequent strongly curved stitches. During the formation of the seam, the workpiece W is rotated by the air exiting from the air nozzle 81, and when the workpiece W reaches again above the opening and closing point 88, a signal is generated by the reflective photoelectric device 85 and thereby defined in the control device. After the delay time, the air supplied to the hollow plate 72 is cut off. In order to ensure that the workpiece W continues to rotate beyond the opening and closing point 88, which is laterally remote from the contact edge 64, for example to position C in FIG.
Such a delay time is necessary. When forming seams in other arcuate sections, the workpiece W is guided and rotated as described above. When the workpiece W leaves both opening and closing points 87 and 88 at the end of the seam, the thread cutting process and the operation of the pneumatic actuating cylinders 31 and 68 take place as usual, so that the finished workpiece W can be transferred to the sewing machine. It can be taken out from 1.

Since the hollow plate 72' shown in partial cross section in FIG. 8 corresponds in its basic structure to the hollow plate 72 shown in FIGS. 6 and 7, the above considerations also hold true regarding its operation mode. This hollow plate 72'
has an upper plate 74' and a lower plate 75' defining a compressed air distribution space 80' therebetween. Unlike the arrangement according to FIGS. 6 and 7, the direction of the air nozzle 81' is adjustable.
For this purpose, these air nozzles 81', which are inclined downward at an acute angle of 30 to 60 degrees with respect to the plate surface, are formed on the rotary member 91, and the lower head 92 of the rotary member 91, which is formed approximately in the form of a flange, , lower plate 75'
It is arranged in a notch 93 on the lower surface of the . This notch 93 widens into a truncated cone shape, while the head 92
The circumference tapers downward in the shape of a truncated cone. Air nozzles 81' open into each of these wedge-shaped spaces. The rotary member 91 is held and guided in a corresponding hole 95 in the lower plate 75' with a head 94 which follows the head 92 upwardly and in a rotatable manner as tightly as possible.

A hole 103 is provided in the top plate 74' and is coaxial with and has a larger diameter than the hole 95.
A rotary member 91 having a threaded portion 97 at the upper end passes through a bush 96 provided in the rotary member 3 . This rotating member 91 is screwed with a nut 98 via a washer 99. The bushing 96 is provided with a spacing ring 100 at its inner end;
The distance between the upper plate 74' and the lower plate 75' is determined by the axial dimension of. This spacing ring 100 is connected to the lower plate 7.
5' has a plurality of radially extending passages 101 which ensure the connection of the compressed air distribution space 80' with the respective air nozzle 81' and thus also form a truncated cone. An annular passage 102 is formed in the inner peripheral surface of the bushing 96. Before final tightening of the nut 98, the respective rotary member 91 is oriented such that the air nozzle 81' extends exactly tangential to the respective partial circle 82 or 83.

In this configuration, the upper plate 7 can no longer be fixed with rivets or the like.
It goes without saying that there is no need to connect 4' and the lower plate 75'. This is because the rotating member 91, together with the nut 98 and the spacing ring 100, assumes the coupling function.

As can be seen from FIG. 6, a workpiece braking device 104 is provided in front of the needle passage hole 611 in the sewing direction 89. As shown in FIGS. 9 and 10, this braking device 104 essentially consists of a brush 105 whose bristles 106 extend downward from a cantilevered brush body 107 to the base plate 2 as a retaining plate and the contact edge 64. facing toward These bristles 106 make an angle α of 30 to 60°, preferably 45°, with respect to the substrate 2, the apex of this acute angle being on the side remote from the contact edge 64. The area of the brush body 107 without bristles 106 is connected to the base plate 2 and thus to the stop 63 by screws 108, but it is also possible to connect this brush body 107 directly to the stop 63. The area of the brush body 107 having bristles 106 is long compared to its width, and its longitudinal axis extends at right angles to the sewing direction 89 (FIG. 6). The brush 105 is attached just before the stopper 63 when viewed in the sewing direction 89. hair 106
If it projects beyond the contact edge 64, the part with the part with its center is placed in front of the needle 8.

The bristles 106 can extend to the substrate 2, but can also end just above it. What is important is that when the work piece W is present, these hairs 106
contacts the upper surface of the workpiece W, and the workpiece contacts the contact edge 6
This is to prevent them from being separated from 4. In particular, the work piece W is moved to the contact edge 6 by the air nozzles 81, 81'.
4, this workpiece touches the contact edge 64
This prevents it from rebounding.

The braking device 104 or the brush 105 is the hollow plate 7
2 or 72'.

[Brief explanation of drawings]

FIG. 1 is a rear view of a sewing machine according to the present invention, FIG. 2 is a side view of the sewing machine as seen in the direction of the arrow in FIG.
3 is a plan view of the board as seen in the direction of the arrow in FIG. 1, FIG. 4 is a perspective view of the seam forming range of the sewing machine as seen in the direction of the arrow in FIG. 1, and FIGS.
Figure c is a side view of the sewing machine at different stages of needle movement in the seam forming range of the sewing machine as seen in the direction of the arrow in Figure 1;
Fig. 6 is a plan view of the seam forming range with the rotating device as seen in the direction of the arrow in Fig. 1, Fig. 7 is a sectional view taken along the cutting line - in Fig. 6, and Fig. 8 is a modification of Fig. 7. 9 is a front view of the workpiece braking device as seen in the direction of the arrow in FIG. 6, and FIG. 10 is a side view of the workpiece braking device as seen in the direction of the arrow X in FIG. be. 1... Sewing machine, 2... Holding plate (board), 5...
Upper shaft, 8... Needle, 9... Pressing rod, 10... Pressing foot piece, 13... Feeding piece for workpiece (toothed belt),
58... Feed dog, 61... Needle passing hole, 63... Stopper, 64... Contact edge, 72, 72'... Hollow plate, 81, 81'... Air nozzle, 82, 83...
...Partial view, H...Elevating transmission device, W...Workpiece.

Claims (1)

[Scope of Claims] 1. A work piece feeding device has at least one work piece feed dog and a pressing foot piece which are provided below the work piece and performs intermittent feeding, and the work piece on the holding plate has an edge thereof. is guided along the contact edge 64 and a rotating device provided above the workpiece is capable of rotating the workpiece about an axis coincident with the needle, the rotating device being concentric with respect to the needle passage hole 61. a plurality of air nozzles 81, 81' distributed on at least one partial circle 82, 83 and oriented tangentially to this partial circle and at an acute angle to the plate surface of the holding plate; An elevating transmission device H is provided which separates the pressing leg 10 from the workpiece W at the timing of the stabbing of the needle 8, which can move up and down through the upper shaft 5, so that the needle 8 sticks into the workpiece W and almost dies at the bottom. Sewing machine with a feeding device and a rotating device for the workpiece to be sewn, characterized in that the pressing foot 10 is moved away from the workpiece W during the downward movement until reaching a point. 2. The air nozzles 81, 81' of the rotating device are formed in the hollow plates 72, 72',
A sewing machine according to claim 1. 3. The sewing machine according to claim 2, wherein the hollow plates 72, 72' are arranged directly above the work piece W but not in contact with it. 4. Claims characterized in that the air nozzles 81, 81' are arranged approximately on a semicircle 82, 83 as a partial circle around the needle passage hole 61 on the side remote from the contact edge 64 The sewing machine according to paragraph 1. 5. The sewing machine according to claim 2, wherein the hollow plates 72, 72' are configured to be able to swing upward. 6. Sewing machine according to claim 1, characterized in that the air nozzle 81' is adjustable in its tangential direction. 7. The device according to claim 1, 2, 4, or 6, characterized in that compressed air can be supplied to the air nozzles 81, 81' only at arcuate or square seams. sewing machine. 8. Claims characterized in that the elevating transmission device H has a cam 28 that can be driven by the upper shaft 5, and that this cam is connected to the pressing rod 9 of the pressing leg 10 via a transmission link mechanism. The sewing machine according to paragraph 1. 9. The sewing machine according to claim 1 or 8, wherein the rising height a of the pressing foot 10 is adjustable. 10. The sewing machine according to claim 1 or 8, characterized in that the raised position of the pressing leg 10 is adjustable. 11. Sewing machine according to claim 1, characterized in that a workpiece brake device 104 is provided next to the contact edge 64, pointing towards the holding plate. 12. Sewing machine according to claim 11, characterized in that the workpiece brake device 104 is configured as a brush 105 with bristles 106 pointing towards the holding plate. 13. The sewing machine according to claim 12, characterized in that the bristles 106 are provided inclined towards the contact edge 64. 14. The sewing machine according to claim 13, wherein the bristles 106 are inclined at an angle of 30 to 60 degrees with respect to the holding plate. 15. Sewing machine according to claim 12, characterized in that the brush (105) is of elongated construction and is arranged approximately at right angles to the contact edge (64). 16. Sewing machine according to claim 11, characterized in that the workpiece brake device 104 is connected to the contact edge 64.