GB2135703A - Warning device - Google Patents

Abstract

A warning device comprises switch actuating means (5), a switch (6) and an indicating lamp (8) which are attached to a sewing machine 1. The switch actuating means is arranged to actuate the switch if a particular sewing machine variable (for example thread tension) reaches a preset value. When the switch is actuated an electric circuit is closed which causes the indicating lamp to light up, thereby warning the machine operator that the preset value has been reached. <IMAGE>

Description

SPECIFICATION Warning device This invention relates to a warning device for use with sewing machines.

The efficient operation of a sewing machine involves accurately controlling a number of variables which affect the quality of work which the machine produces. Examples of such variables are thread tension, stitch length, bobbin winder tension and foot pressure.

Many sewing machines are provided with means to adjust the value of these variables in order to enable a machine operator to run the machine over a range of values.

This range depends on a number of factor such as the nature of thread and the material being sewn.

It is possible to adjust the variables to extreme values outside an acceptable limit and this can cause a severe deterioration in the quality of work produced. For example if the thread tension is adjusted to too high a value, then the detrimental phenomenon of puckering will occur. However, in the normal operation of a machine the operator is unlikely to operate the machine at these extreme values.

The most significant problems arise when a fault develops on the machine. The operator, who may not realise that a fault is present, may change one or more of the variables in order to compensate for the effects of the fault. This action is likely to cause the value of each adjusted variable to fall outside the desired range.

According to the present invention there is provided a warning device for use with a sewing machine comprising switch-actuating means, a switch, and indicating means, wherein the switch actuating means is arranged to detect a variable associated with the sewing machine, and to actuate the switch when the value of the detected variable falls above or below a preset value, said switch being capable of activating the indicating means, to indicate that the variable has fallen above or below the preset value.

Advantageously the switch-actuating means comprises a member, a first end of which is attached to the sewing machine, and can move with respect to the sewing machine in response to changes in the variable. Preferably a second end of the member is capable of engaging, and thereby actuating, the switch.

It is desirable that the indicating means is a lamp arranged on top of the sewing machine. The switch may conveniently be a micro-switch and preferably is provided with a switch element against which the second end of the member can engage in order to actuate the switch.

The present invention enables a sewing machine to be operated with its variables continuously maintained within a preset range of values. If a variable falls outside the preset range then operation can immediately be stopped, and a mechanic can be called to check the machine for faults. The employment of the invention can result in significant reductions in the occurrence of such major problems as puckering and crack-stitch.

Since the operator is immediately notified that a problem is present, considerable economies may be made in terms of losses of materials and of time.

Reference is now made to the accompanying drawings in which: Figure 1 is an elevation of a sewing machine incorporating a warning device according to the invention; and Figure 2 is a plan view of the sewing machine and warning device as shown in Figure 1.

In the drawings a sewing machine generally designated 1 includes a machine casting arm 2 and a sewing head 3. Mounted upon the sewing machine 1 is a warning device generally designated 4 which comprises a switch actuating member 5, a switch 6 and an indicator 7.

The indicator 7 consists of a mounting to which an indicating lamp 8 is affixed. The indicator 7 is mounted on the arm 2 by means of screw 9.

The indicating lamp 8 forms part of an electric circuit which includes a power source (not shown) and the switch 6. The power source may conveniently be a 12 volt battery.

The switch 6 is mounted on the arm 2 by means of screws 10 and 11. A switch element 12 is provided and enables the electric circuit to be opened and closed. The electric circuit can be closed by depressing the switch element 1 2. The switch element 12 can be released in order to open the electric circuit, and the element is biased so that it will remain in the open circuit condition unless a force is applied to depress it.

A thread tension adjuster generally designated 1 3 is shown attached to the head 3. The tension adjuster 1 3 comprises an adjustment wheel 14, tension discs 1 5 and 16, a tension rod 17 and a tension spring 1 8. The switch actuating member 5 is connected to the tension rod 1 7. A sewing thread (not shown) passes beween the tension discs 1 5 and 16.

The tension applied to the thread can be altered by rotating the adjustment wheel 1 3 which causes the switch-actuating member 5 to move against the tension spring 1 8 which applies increased pressure to the discs 1 5 and 1 6 thereby resulting in increased thread tension. As the tension increases the switch actuating member 5 moves closer to the switch element 12. If the tension is increased beyond a desired preset tension, then the switch actuating member 5 will engage and depress the switch element 1 2 and thereby cause the lamp 8 to be switched on.

Before the warning device can be operated it is necessary initially to calibrate the system so that the switch element 1 2 is depressed by the switch actuating member 5 at the desired preset tension.

Further switches (not shown) could be added to the system so that an indicating lamp is switched on when a certain minimum value of variable is reached.

The indicating lamp could be replaced or supplemented with an alarm beil, and it is also possible to connect all the devices to a central control board from where several sewing machines could be monitored.

When the sewing machines are used on an industrial scale they are usually arranged one in front of each other in a line. The indicating lamps can be arranged at such an angle that they are visible both to the individual operator and to a person standing at the head of the line.

The switch described above is of the on/off type, but this could be replaced by a proportional switch which could be connected to a digital indicator in order to give an indication of the value of a variable.

Claims (6)

1. A warning device for use with a sewing machine comprising switch-actuating means, a switch, and indicating means, wherein the switch actuating means is arranged to detect a variable associated with the sewing machine, and to actuate the switch when the value of the detected variable falls above or below a preset value, said switch being capable of activating the indicating means, to indicate that the variable has fallen above or below the preset value.

2. A warning device according to Claim 1 in which the switch actuating means comprises a member, a first end of which is attached to the sewing machine, and can move with respect to the sewing machine in response to changes in the variable.

3. A warning device according to Claim 2 in which a second end of the member is capable of engaging, and thereby actuating, the switch.

4. A warning device according to Claim 3 in which the switch is provided with a switchelement which the second end of the member can engage.

5. A warning device according to any preceding claim in which the indicating means comprises a lamp arranged on top of the sewing machine.

6. A warning device substantially as herein described with reference to and as shown in the accompanying drawings.