JPH0117269Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Object of the Invention] The present invention relates to an improvement of a bobbin slip prevention device in a sewing machine.

(Field of Application of the Present Invention) The above-mentioned idling prevention device can be used not only for industrial sewing machines and household sewing machines, but also for equipment that prevents thread from being drawn out too much, such as fishing reels.

[Conventional technology]

In recent years, in order to improve sewing efficiency, sewing machines have been made faster and equipped with automatic thread cutting devices. However, a new problem is that the bobbin spins idly due to the sudden start and stop of the sewing machine and the sudden release of the bobbin thread during thread trimming, resulting in frequent sewing defects due to bobbin thread coming off, bobbin thread getting tangled, etc.

In order to solve this problem, various slip prevention devices have been proposed. As an example, in the 49th
There is a device described in the -45857 publication.

In this device, four arc-shaped elastic pieces are always provided between the inside of the bobbin case and one surface of the bobbin in a radial direction with respect to the central axis of the bobbin case, and pressed against the bobbin.

[Problems with conventional technology and their technical analysis]

In this conventional bobbin slip prevention device, the shape of the elastic piece that comes in contact with the side surface of the bobbin is circular with a wide contact area, and the shape of the elastic piece is independent of the direction of rotation of the bobbin, so it is effective in preventing slip. However, the disadvantage is that the lower tension becomes unstable.

[Technical issues]

Therefore, the technical problem of the present invention is to obtain stable bobbin thread tension.

[Technical means]

The technical means taken to solve the above technical problem is to provide a central shaft integrally protruding from the back surface of the center side of the inner pot, and attach an idling prevention spring to the central shaft in close contact with the back plate surface of the inner pot. The idling prevention spring is pressed with a plurality of claws so that the idling prevention spring is bent toward the back plate surface side, and the idling prevention spring is pressed with a plurality of claws, and an elastic piece is attached to the idling prevention spring along the rotational direction of the bobbin. The elastic piece is formed by cutting and raising it, and the contact portion of the elastic piece with the bobbin is rounded.

[Effect of technical means]

The said technical means work as follows. That is, the bobbin 7 is rotated by contacting the elastic piece 6b of the idling prevention spring 6.
are cut and raised along the circumferential direction of the bobbin 7, so that the rotation inhibiting force is smoothly applied to the side surface of the bobbin 7. The contact portion of the elastic piece 6b with the side surface of the bobbin 7 has a smooth roundness 6b' and is in pressure contact with the side surface of the bobbin 7 with an even load, and since the contact area is small, there is no rotational restraining force. There will be no continuous bad luck. Therefore, when the sewing machine is stopped, the bobbin 7 tries to rotate due to inertia, but the rotation prevention force of the idling prevention spring 6 prevents it from idling, and the stability of the rotation prevention force keeps it stable at all times when the sewing machine is running. A lower thread tension can be obtained. Further, in such an action, when the bobbin case 8 is attached or detached, the slip prevention spring 6 presses the bobbin 7 toward the inner surface of the bobbin case 8.

[Special effects produced by the present invention]

The present invention produces the following unique effects. In other words, by locking the idling prevention spring to the back plate of the inner hook, it pushes the bobbin toward the inner surface of the bobbin case, which makes it easier for the locking piece to catch on the locking step and prevent the bobbin from entering the inner hook. In addition, the idling prevention spring is pressed by a plurality of claws so as to be in close contact with the back plate surface of the inner pot. An elastic piece is cut and raised along the direction of rotation of the bobbin on the idling prevention spring, and the contact part of the elastic piece with the bobbin has a smoothly rounded shape, so the shape of the commercially available inner pot is changed, It can be installed with one touch without any additional processing.
Furthermore, for example, even if the direction of rotation of the bobbin is reversed,
Without changing the cutting direction of the slip prevention spring,
This has the effect of stably preventing idling and increasing the tension of the lower thread.

〔Example〕

An example illustrating a specific example of the technical means will be described below.

The inner pot 1 has a peripheral surface 2, a central shaft 4 having a locking step 3, and a back plate 5 that holds the central shaft 4, and the back plate 5 is provided with an anti-idling spring 6. There is. The idling prevention spring 6 has four claws 6a in the center.
is formed so as to be firmly attached to the central shaft 4, and protrusions 6c are bent on both sides toward the back plate 5 side, and are shaped like an arc in the direction of rotation of the bobbin 7. Two elastic pieces 6b having smooth roundness are each integrally formed at the bobbin contact portion. Therefore, the slip prevention spring 6 is
Since it is firmly engaged with the central shaft 4, it is fixed in the axial direction, and also fixed in the rotational direction by the protruding piece 6c. Also bobbin case 8
is provided within the circumferential surface 2, and the bobbin case 8 is
It has a cylindrical shaft 9 that fits into the central shaft 4 and a locking piece (not shown) that engages with the locking step 3, and a bobbin 7 is inserted into the cylindrical shaft 9. The bobbin 7 is joined under equal load by the two elastic pieces 6b of the idling prevention spring 6, and extends toward the inner surface of the bobbin case 8.
Being pressed.

[Brief explanation of the drawing]

Fig. 1 is a plan view of an inner hook equipped with an idling prevention spring showing an embodiment of the present invention, and Fig. 2 is a plan view of an inner hook bobbin case fitted with an idling prevention spring showing an embodiment of the invention. FIG. 3 is a perspective view of an idling prevention spring showing an embodiment of the invention, and FIG. 4 is a side view of an idling prevention spring showing an embodiment of the invention. 1... Inner pot, 4... Center shaft, 5... Back plate, 6...
...Idling prevention spring, 6a...claw, 6b...elastic piece,
6b'...Roundness, 6c...Protrusion, 7...Bobbin, 8
...Bobbin case.

Claims (1)

[Scope of utility model registration request] In a bobbin slip prevention device in which a bobbin is inserted inside a bobbin case and a slip prevention spring is constantly pressed between the side surface of the bobbin and the back surface of an inner hook, a center shaft is integrally attached to the center inner back surface of the inner hook. and a plurality of claws press the idling prevention spring onto the central shaft so as to bring it into close contact with the back plate surface of the inner pot,
Protrusions are formed on both sides of the idling prevention spring by bending them toward the back plate surface, and elastic pieces are cut and raised on the idling prevention spring along the rotational direction of the bobbin, and the elastic pieces are attached to the bobbin. A device for preventing slippage of a bobbin in a sewing machine, characterized in that the contact portion with the bobbin is rounded.