JPS5814940Y2 - Thread tension device - Google Patents

Description

[Detailed description of the invention] The present invention relates to a thread tension device for sewing machines.In order to obtain an appropriate upper thread tension depending on the type of sewing, the upper thread tension device is adjusted in conjunction with the sewing type selection operation. The thread tension can be adjusted.

A zigzag sewing machine can usually perform multiple types of stitches, but it is necessary to vary the vertical position of the intersection of the upper thread and bobbin thread on the cloth due to the appearance, strength, fabric shrinkage, etc. of the seam. be.

For example, in the case of straight stitching as shown in Figure 3, it is desirable to position the intersection of the upper thread and lower thread in the center of the right bank as shown in the figure, in order to strengthen the seam strength and create a beautiful finish. .

On the other hand, in zigzag stitching, if the bobbin thread is visible on the upper surface of the fabric, it will spoil the aesthetic appearance and cause the fabric to shrink, so it is desirable to position the intersection of the needle thread and bobbin thread below the right bank, as shown in Figure 4. .

It is also desirable to adjust the tension of the needle thread to suit each zigzag pattern.

However, conventional sewing machines have the inconvenience of having to adjust the thread tension separately from the sewing type selection operation.

Furthermore, it is difficult to obtain an appropriate thread tension for each type of sewing using a conventional needle thread regulator, and the disadvantage is that the operator has to rely on the experience and intuition of the operator. Ta.

The present invention was devised to eliminate the drawbacks of the conventional products as described above, and an embodiment thereof will be explained below with reference to the drawings. Fixed.

Numerals 4 and 5 are thread tension discs that are fitted into the small diameter portion 6' of the plunger 6 of the solenoid, and are held between the support plate 7 and presser plate 8, which are also fitted, and are connected to the side surface of the stator 2 and the arm 3. It is possible to move slightly in the axial direction between the side surface of the

Reference numeral 9 denotes a stopper which restricts the relative movement of the presser plate 8 in the axial end direction of the small diameter portion 6', and screws the holding plate 8 onto the small diameter portion 6' so that its position can be adjusted in the axial direction.

The attachment is done with a slight clearance in the axial direction so that the thread tension discs 4 and 5 are not pinched between the stopper and the large diameter portion 6'' of the plunger 6.

Note that 10 is a coil of the solenoid 1.

In the above-mentioned installation, the residual movement amount G of the plunger 6 when the solenoid 1 is excited and the thread tension discs 4 and 5 are pinched can be adjusted by the mounting bracket 9. For example, if the tension discs 4 and 5 are made larger, the clamping force of the thread tension discs 4 and 5 is adjusted to be smaller.

In this case, the solenoid 1 is one in which the suction force changes gradually in response to changes in the residual movement amount G in order to facilitate adjustment of the clamping force.

FIG. 2 is a circuit diagram for controlling the solenoid 1,
In series with the coil 10 is a variable resistor 11 which can be operated with a dial (not shown) provided on the head of the sewing machine to adjust the excitation current, and a stopper 9 when adjusting the assembly of the sewing machine. One of them is selectively enabled by turning on or off a semi-fixed resistor 12 for adjustment in parallel with the adjustment of the sewing machine, and a number of switches S1 to So equal to the type of sewing of the sewing machine or the number n of groups thereof. In this way, a set of resistors R1 to R for controlling the excitation current is connected, and is DC-energized via the rectifier stack 13 by the power source (2).

Each of the switches S1 to So is a pattern selection operation section 14.
The switch is mechanically or electrically linked to the operation of the switch, and the switch appropriate for each pattern is selected and operated in response to the selected pattern.

In the above configuration, the attraction force of the solenoid 1 increases or decreases by increasing or decreasing its excitation current, so when a pattern is selected by the pattern selection operation section 14, for example, the resistor R1 becomes effective, and the coil 10 is connected to the resistor and each of the above-mentioned components. Resistance R1, 11, 1
A current determined by 2 flows, and an upper thread clamping force suitable for the pattern is generated between the thread tension discs 4 and 5 according to the current.

When another pattern is selected, for example, the resistor R1 becomes effective instead of the resistor R1, and the newly selected resistor Rn
A predetermined current flows through the upper thread, and in accordance with the current, an appropriate upper thread clamping force is generated for the newly selected pattern, which is different from the previous clamping force.

The variable resistor 11 is used for fine adjustment in order to obtain the optimum upper thread clamping force for the pre-existing pattern, and after that, adjustment is generally not required for each selected pattern, but specific requirements have arisen. Sometimes used for fine adjustment.

As described above, according to the present invention, it is possible to appropriately and easily select the needle thread tension suitable for the pattern, and the needle thread tension knob can be placed at any location, and furthermore, it is easy to operate by simply moving the variable resistance. It is sufficient and easy to handle, so it has a great effect from an industrial practical point of view.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the structure of a thread tension device according to an embodiment of the present invention, FIG. 2 is an excitation current control circuit diagram for controlling the thread tension device, and FIGS. 3 and 4 are straight lines, respectively. FIG. 7 is a perspective view of stitches showing uncrossed positions of stitches and uncrossed positions of zigzag stitches. In the figure, 1 is a solenoid, 4 and 5 are thread tension members, 14 is a pattern selection operation section, S1 to Sn are switch members, and resistors R1 to R.
, is an excitation current setting member.

Claims (1)

[Scope of utility model registration request] In a sewing machine that can perform multiple types of sewing,
a pattern selection operation section for selecting one of the stitches, a thread tension member for adjusting the needle thread tension by pinching the upper thread, and adjusting the clamping force of the thread tension member to a plurality of levels by electromagnetic force. a solenoid that adjusts the amount of the excitation current; an excitation current setting member that sets the excitation current of the solenoid to a plurality of levels; A thread tension device comprising: a current setting member; and a plurality of switch members for selecting the level of the excitation current for a selected pattern.