RU2036994C1 - Device for guiding lug-clamped thread over to reverse side of stitched material on sewing machine - Google Patents

Abstract

FIELD: clothing industry. SUBSTANCE: device comprises thread-drawing mechanism, needle mechanism, shuttle mechanism, lug unit including a rod with lug and provided with a mechanism for short-term relief of lug pressure on material, needle thread clamp located between needle and thread drawing mechanism, and a means for control of short-term relief of lug pressure on material and of needle thread clamping time depending on shuttle turning angle. Mechanism for short-term relief of lug pressure on material is mounted along the axis of movement of lug unit rod. EFFECT: simplified design, wider technological capabilities when dealing with materials of different thickness, achieved by short-term lifting of lug above stitched material for free pulling of needle thread end by shuttle from under the lug over to reverse side of material at the beginning of stitching. 2 cl, 3 dwg

Description

 The invention relates to sewing machine-building, in particular to devices for pulling the free end of the needle thread from the upper side of the material being sewn to the lower, wrong side.

 A known method of penetrating into the fabric of the free end of a needle thread on a sewing machine.

 The device according to this method, during the first stitch, at the moment the needle moves between the bottom dead center and the top dead center at a low speed, they carry out the capture of the hook-and-loop shuttle nose, weaving with the shuttle thread and, when the foot is raised, deepens the free end into the thickness of the fabric. At the same time, the stitched fabric remains motionless during the first stitch of the stitch.

 The disadvantage of the method and device for its implementation (a software electronic control device is mentioned in the patent) is that the shuttle will pull both parts of the needle thread with its nose: the cut-off free end and the part that is between the needle and the thread take-up. Therefore, with a large supply of thread between the needle and the thread take-up, the hook nose may not stretch the trimmed end of the needle thread to the wrong side of the material and leave it on the front side.

 There is another way to pull the free end of the needle thread from the upper side of the sewn material to the lower and the device for its implementation, selected for the prototype.

 With the help of the device, the supply of thread from the thread take-up is prevented for weaving with the shuttle thread in the initial sewing period, when the needle moving from the lower position to the upper one is still in the material and a loop-inlet is formed to capture it with the hook nose. To do this, at the time of the shuttle capturing the needle thread loop-inlet, compressed air is supplied to the pneumatic clamp located between the thread take-up and the needle and the thread is clamped. In order for the hook nose to be able to stretch the end of the needle thread from under the presser foot without breaking it to the wrong side of the material, the presser foot is removed for a short time (compressed air is removed from the pneumatic cylinder, which presses the piston down, on the bar and foot). However, the weights of the foot, the rod with the piston, and the spring force pressing the end of the thread remain.

 To raise the presser foot at the end of sewing, compressed air is supplied from the bottom of the piston and the stem with the presser foot rises up to the stop with a shoulder in the lower part of the pneumatic cylinder.

 The described device uses a different working medium, compressed air, which is used in garment factories not as widely as electricity. This reduces its operational capabilities for use on sewing machines. At the same time, the use of compressed air complicates the design and operation due to the need for additional use of pneumatic devices for preparation, regulation, control and management, as well as the associated electrical devices.

 Another disadvantage is that when changing the thickness of the material being sewn, it is necessary to accurately reconfigure the electric and pneumatic devices depending on the signal of the position sensor reflecting the angle of rotation of the main shaft of the sewing machine. This is due to the fact that with a large thickness of the material (6.8 mm), the pressure force of the foot due to the preload of the spring is large enough and the likelihood of breaking the needle thread when pulling it to the wrong side increases.

 The aim of the present invention is to simplify the design and expand the technological capabilities of sewing materials of different thicknesses by briefly raising the presser foot over the material to be sewn so that the shuttle can freely pull the end of the needle thread from under the presser foot to the wrong side of the material at the beginning of sewing.

 This goal is achieved by the fact that in the device for transferring the end of the needle thread clamped under the presser foot to the seamy side of the sewing material on the sewing machine containing the thread take-up, the needle mechanism, the shuttle mechanism, the presser foot assembly including the bar with the presser foot and equipped with a mechanism for short-term pressure reduction of the presser foot on the material , a needle thread clamp located between the needle and the thread take-up, and means for controlling a short-term decrease in the pressure of the presser foot on the material and the time of the needle thread clamp, depending on the angle of rotation of the shuttle, according to the invention, the mechanism for briefly reducing the pressure of the foot on the material is mounted along the axis of movement of the rod of the foot assembly and includes a sleeve that spans the rod with movement along its axis, a brake shoe integrated in the sleeve in contact with a support which is stationary relative to the rod and connected by a link system with a power tool, and between the sleeve and the bracket fixed in the upper part of the rod, an elastic element is installed. The needle thread clamp contains an electromagnet with a core and plates between which the needle thread is passed, while one plate is made as an electromagnet anchor, and the plate located between the core, needle thread and the anchor plate is made of non-magnetic material.

 Comparative analysis with the prototype shows that the inventive device is characterized by the presence of a new design mechanism for short-term pressure reduction of the presser foot on the material (lifting the presser foot over the material to be sewn), which is mounted along the axis of movement of the bar of the presser foot assembly and includes a sleeve that spans the bar and can be moved along its axis includes a brake shoe built into the sleeve, which is in contact with a support which is stationary relative to the rod and is connected by a system of links with power means, and between the sleeve The bracket and the bracket fixed in the upper part of the rod contain an elastic element. In addition, the needle thread clamp contains a small-sized electromagnet and plates in contact with the core of the electromagnet for clamping the thread, the plate closest to the core is made of non-magnetic material.

 The presence of these differences allows us to conclude that the device meets the criterion of "novelty."

 In the patent and scientific literature, no devices with similar distinctive features were found. The claimed combination of features allows to solve the goal.

 The design of the device is simplified as much as possible, the main part of the parts is located inside the front of the sewing machine head housing.

 In this regard, we can conclude that the invention meets the criterion of "substantial novelty."

 In FIG. 1 shows a kinematic diagram of a device that shows the moment the shuttle nose enters the loop of a needle thread; in FIG. 2 moment at the beginning of sewing; in FIG. 3 moment of drawing the needle thread on the wrong side of the material.

 In FIG. Figure 1 shows that the end of the needle thread 1 is pressed under the foot 2 of the foot assembly 3. Then the thread passes through the material 4, under the nose 5 of the hook 6, again through the material of the needle eye 7 of the needle mechanism 8. After the needle, the thread is passed between the small plates 9 and 10 the electromagnet 11 and further through thread guides (not shown) into the eye of the thread take-up 13. The foot assembly 3 includes a rod 14 that can axially move through the sleeve 15 pressed into the front of the machine head 15. A bracket 16 is fixed to the upper part of the sleeve 15 with a support 1 7. Above the brackets on the rod there is a sleeve 18 movable along the axis of the rod with an integrated brake pad 19. The latter has a rocker 20 with hinges 21 and 22, the hinge 22 being supported on a support 17 and connected by links 23 to the rod 24 of a power tool 25, for example an electromagnet. Between the sleeve 18 and the bracket 26 fixed in the upper part of the rod, a compression spring 27 is placed. To press the rod 14 with the tab 2 to the material 4, a leaf spring 28 with an adjusting screw 29 of a known design is used. The electromagnets 25 and 11 are connected with the control means 30 for a short-term reduction in the pressure of the presser foot on the material and the clamping time of the needle thread, depending on the angle of rotation of the main shaft of the sewing machine.

 The device operates as follows.

 After laying and orienting the material 4, the end of the needle thread 1 hanging from the eye of the needle 7 (Fig. 2), when lowering the tab 2 with a significant degree of probability, is pressed by the foot to the front side of the material (Fig. 1). Lower the foot with a slight lead ahead of the inclusion of the needle mechanism. Next, the needle 7 punctures the material, passes the bottom dead center and, when moving upward, forms a loop-inlet, which captures the nose 5 of the shuttle 6 (Fig. 1).

 At this moment, under the action of the control 30, the electromagnets 25 and 11 are simultaneously triggered. The electromagnet 11 clamps the thread between the two plates 9 and 10, while the plate 9 closest to the core of the electromagnet is made of non-magnetic material, such as brass or aluminum, to eliminate permanent adhesion plates to the core due to residual magnetism. Therefore, when the electromagnet is not turned on, the thread 1 slides freely between the plates 9 and 10. The plate 10 performs the function of the armature of the electromagnet 11.

 Another small-sized electromagnet 25 with low inertia and a high degree of speed is selected so that through a system of reinforcing links 23 to transmit a force that can lift the rod 14 with tab 2, pre-pressed by the spring 28 with a load of about 100 N. The spring 27 serves to return the system 18, 19 , 20, 21 and 22 to the starting position.

Lift 1 of the rod 14 with the tab 2 is carried out by pressing the pads 19 to the surface of the rod 14 when the hinge 22 moves up under the short-term action of the electromagnet 25 through the reinforcing links 23. The sleeve 18 connected to the block 19 will also make a short upward movement, lifting the spring 28 ( Fig. 3). The rise lasts during the time the shuttle 6 rotates through an angle of about 180 ^about . As a result, the free end of the needle thread will be pulled by the hook nose onto the wrong side of the material. The other branch of the needle thread from the needle towards the thread take-up at this time is clamped by the plates 9 and 10. Lift can be performed when sewing light, medium and heavy materials without additional adjustment, since the operation of the device does not depend on the vertical movement of the bar 14.

Claims (2)

 1. A DEVICE FOR TRANSFER OF A NEEDLE THREAD CLAMPED UNDER A PAW OF THE SEWING TO A WRENCHED PART ON A SEWING MACHINE, containing a thread take-up, a needle mechanism, a shuttle mechanism, a hook mechanism, a presser foot, including a pressure reducing mechanism with a presser foot and a presser foot , a needle thread clamp located between the needle and the thread take-up, and means for controlling a short-term decrease in the pressure of the presser foot on the material and the time of the needle thread clamping depending and from the angle of rotation of the shuttle, characterized in that the mechanism for short-term pressure reduction of the foot on the material is mounted along the axis of movement of the rod of the foot assembly and includes a sleeve that spans the rod with the ability to move along its axis, a brake shoe integrated in the sleeve in contact with the support fixed relative to the rod and connected by a system of links with a means of force, and between the sleeve and the bracket fixed in the upper part of the rod, an elastic element is installed.  2. The device according to claim 1, characterized in that the clamp of the needle thread contains an electromagnet with a core and plates between which the needle thread is passed for short-term clamping at the time of operation of the electromagnet, at least one plate is made as an anchor of the electromagnet, and the plate located between the core, the needle thread and the anchor plate is made of non-magnetic material.