DE1816353B2 - sewing machine - Google Patents

Description

is

The invention relates to a sewing machine with a main clutch that can be actuated forwards by depressing a pedal and a synchronizer with a known from practice --.-. ^v ii-! machine of the type mentioned (see also brochure of the company

Quick Rotan Becker + Co. Darmstadt, 1963) the arrangement is such that when you let go of the with the pedal depressed at the front, which then returns to its neutral rest position, the sewing gauge machine drive is stopped when the needle is in the lowest position; in this position can the material in the sewing machine can be rotated around the needle. For cutting the thread the pedal must be stepped backwards, the needle at reduced speed in the highest position Position moves and the thread cutter is actuated as soon as the needle is lifted out of the needle plate Has. The needle is also stopped in the lowest position if only the thread is cut shall be. This causes an unnecessary delay in the cycle time of an operation and in addition, an unnecessary load on the sewing machine drive.

A sewing machine with a mechanical device that can be actuated by a hand lever is also known to initiate the movement of a thread cutter (cf. DT-AS 1 159 247), whereby the hand lever can also be operated while the sewing machine is still running and the switch-on given in this way pulse is saved until the needle has reached its lowest position. Here too, the sewing machine stopped before the thread cutter operates. The latter also applies to another well-known Sewing machine (see. FR-PS 1490 285) in an embodiment known from practice, in which the Thread trimmer can be operated by means of an electromagnet controlled by a synchronizer.

The invention is based on the task, surprisingly so far overlooked in the professional world, a Specify sewing machine, in which the thread after actuator, the pedal without stopping the needle in the deepest Position can be cut off.

Dts sewing machine according to the invention of the introduction For this purpose, genaiiMeti genus is characterized by a pedal in the foremost position of the pedal over a pedal contact excitable first control relay for closing a first excitation circuit for the electromagnetic clutch and a second control relay, its coil with a second pedal stroke closed in the rearmost pedal position, a normally closed one

Contact of the first control relay and in the topmost needle position open contact of the Synchronize «)« in Row lies wob «! by exciting this second control relay, a second excitation circuit for the electrical

magnetic coupling can be closed, via which the After reaching the lowest position, the needle can be brought to its highest position and locked there, and the thread is electrically controlled during this movement through the upper an additional contact of the synchronizer ten thread cutter is separable

The sewing machine according to the invention allows due to the features described, by moving the Pedals move the needle from the front to the rear position at a reduced speed lowest position, then move in a continuous transition to the highest position and in the train the upward movement of the needle to operate the thread cutter.

The advantages achieved by the invention are consequently to be seen in the fact that a sewing machine with shortened work cycle times is created, the drive thereof does not experience any unnecessary stress.

According to a preferred embodiment, the first control relay has a changeover contact for alternately switching on the excitation circuits of the electromagnetic clutch or the electromagnetic brake and this is connected in series with a changeover contact of the second control relay, the latter switching contact with the second excitation circuit when the second control relay is excited the electromagnetic clutch can be closed. Independently of this, but also in combination with it, the arrangement is preferably made so that the second control relay has an additional switching contact and via this, when the second relay is energized, a third relay, which actuates the thread cutter when energized, can be switched on, in whose circuit the additional contact of the synchronizer lies.

In the following the invention is explained in more detail with reference to a drawing; the figure shows schematically the electrical structure of a sewing machine according to the invention.

The sewing machine has an electric drive motor 1 with a motor shaft 2 and a main machine shaft 3 for driving the moving machine parts including the needle (not shown) in their upward and downward movement. The motor shaft 2 can be coupled to the main shaft 3 via a main clutch 4 and can be actuated via a pedal 5 which can be tilted forwards and backwards by the operator from its illustrated central position. The main clutch has a friction disc 6 fixedly connected to the motor shaft 2, a friction disc 7 fixedly connected to one side of a worm wheel 8 seated freely rotatably on an intermediate shaft 9, and a spring-loaded clutch disc 10 which cannot rotate. but is seated axially displaceably on the shaft 9. Via organs known per se and therefore not shown, when the pedal 5 is tilted counterclockwise, the clutch disc 10 is pushed to the left from its central position and thereby engages the friction disc 6, whereby the motor shaft 2 is connected to the intermediate shaft 9 is, while in the middle position of the pedal 5, as well as when this pedal is tilted backwards clockwise, the clutch disc tO rests against the friction disc 7 and thereby connects the worm wheel 8 with the intermediate shaft &. This shaft 9 is connected to the main shaft 3 via a fine belt drive 11.

A dektfomägiietisctas clutch and brake assembly 12 sits on a * shaft 13 with a worm 14 which meshes with the worm wheel 8. This unit 12 has a magnetic coupling element 15 which is freely rotatable on the shaft 13 and carries an excitable clutch winding 16 The unit 12 also has a magnetic brake element 17, which is attached to a stationary part of the machine and carries an excitable brake winding 18. A clutch disc 19 made of magnetic material is also seated on the shaft 13 and is not rotatable, but axially displaceable, so that when the clutch winding 16 is excited this disc is pulled against the friction plate on the member 15 and thereby this member is coupled to the shaft 13, while when the brake winding 18 is excited, this clutch disc 19 is pulled against the fixed part 17 and thereby stops the shaft 13. The magnetic coupling member 15 also carries a pulley 20. which via a belt drive 7 1 is connected to a pulley 22 on the motor shaft 2. As a result, the magnetic coupling element 15 is driven directly and continuously by the drive gate 1.

When the pedal 5 is now depressed forward and thereby the clutch disc 10 against the friction disc 6 is pressed, the Maschinem.hauptwelle 3 from the engine 1 via the main clutch 4 with full Speed driven. However, as soon as the pedal 5 is in its central position or in the rearmost position, in which the clutch disc 10 is pressed against the worm wheel 8, the main shaft 3 becomes connected to the shaft 13 via the worm drive 8, 14, whereby when the clutch winding 16 the main shaft 3 is driven at reduced speed and braked immediately when the brake winding 18 is excited and is stopped.

A synchronizer 23 has a control roller 24 which is rotatably connected to the main shaft 3 and consequently with every up and down movement of the sewing needle one revolution. Dic = e control roller 24 has a body made of insulating material and four contact rings 26 to 29, which with four contact brushes 30 to 33 work together. These contact rings are electrically connected to one another, the ring 27 runs completely around the roller and together with the contact brush 31 the other three contact rings powered. These latter contact rings 26, 28 and 29 extend only over part of the Circumference of the control roller 24, the space between the individual rings for each contact ring is of different widths and is angularly offset.

The contact rings and the contact brushes are arranged in such a way that the brush 33 leaves the ring 39 in the angular position of the control roller 24, which is the lowest position of the sewing needle, and the brush 32 leaves its ring 28 in the angular position of the control roller 24, which is the topmost Needle position corresponds. The Biii ate 30 contacts the short ring 26 v.ährend the final portion of the needle moving from its lowermost to the uppermost position.

The control circuit is provided by a suitable power source 25, for example a normal power line The fed via a transformer 34 with a secondary voltage of 30 V and a rectifier 35 The positive terminal of this rectifier is directly connected to the contact brush 31 of the synchronizer 23.

With the terminals of the rectifier 35 is except ' to which the coil 37 of a first control relay 36 is connected, which is in series with a pedal contact 38.

which is closed in the foremost position of the pedal S and open in the middle and rear position of the pedal. This relay 36 has a normally open switching contact 39, a normally closed switching contact 40 and a changeover contact 41. When the pedal contact 38 is closed and the relay flush 37 is energized, the contact 39 closes a hold circuit for the relay 36 from the positive terminal of the Rectifier 35 via the contact brush 31. the control roller 24, the contact brush 33, the relay contact 39. the relay coil 37 to the negative terminal of the Rectifier 35.

A second control relay 42 has a relay coil 43, one end of which is connected to the negative terminal of the rectifier 35 and the other end of which via the normally closed switching contact 40 of the relay 36. a second pedal contact 44 which is closed in the rearmost position of the pedal 5. the contact brush 32, the control roller 24 and the contact brush 31 are connected to the positive terminal of the rectifier 35.

When both relay coils 43 and 37 are de-energized, is a circuit from the positive terminal of the rectifier 35 via a changeover contact 45 of the relay 42, the Umschahkontakt 41 of the relay 36 and the brake winding 18 of the clutch and brake unit 12 for Minus terminal of rectifier 35 closed. When relay 36 is energized, a similar circuit occurs closed, which, however, now via the Umschahkontakt 41 to the coupling winding 16 of the unit 12 runs. When relay 42 is energized, a circuit is established from the positive terminal of rectifier 35 Closed via the Umschahkontakt 45 directly to the clutch winding 16.

The control relay 42 also has a normally open switch contact 46. which via the Rectifier 35 with a relay coil 48 of a third control relay 47 and the contact brush 30. which with the short contact ring 26 of the control roller 24 cooperates, lies in series. This control relay 47 has a changeover contact 49. which in the rest position, d. H. in the position shown in the figure, the field winding S1 of an electromagnetically controlled valve 50 connects to the rectifier 35 and, when the relay 47 is energized, connects the field winding 53 of the same electromagnetically controlled valve 52 to the rectifier 35. Valves 50 and 52 are on theirs The inlet side is connected to a common air inlet line 54, which leads to a compressed air duct (not shown). The outlets of these valves 50 and 52 are upper lines 55 and 56 with a cylinder 57 connected, the piston 58 of which is connected to a thread trimmer (not shown) via its piston rod 59 if, as shown in the drawing the winding Sf is energized, the valve 50 is opened rch the pressure on the right side of the piston 58 keeps the thread trimmer idle the contact 49 is switched and the winding 51 is switched on and the winding 53 is switched on, the valve 50 is closed and the valve 52 is opened so that the piston 58 exerts its working stroke and the thread trimmer actuated. When the switch 49 is switched over, the piston 58 then returns to its rest position.

The above-described control circuit for the synchronizer 23 and the thread trimmer works as follows: The motor 1 is switched on so that when Depressing the pedal 5 forwards the clutch disk IO is pressed against the friction disk 6 and there through the machine main shaft 3 with normal operating speed of, for example, 5000 to 6000 rpm, is driven. By this actuation of the pedal 5, the pedal contact 318 is closed, so that the Control relay 36 is energized and the changeover contact 41 interrupts the circuit of the brake winding of the clutch and brake assembly 12 and the circuit of the clutch winding 16 of this assembly closes. The excitation of the clutch winding 16

■ ο presses the clutch disc 9 against the rotating part 15. which thereby drives the shaft 13 and Via the worm 14 there is a worm wheel 8. Since this worm wheel is free on the intermediate shaft 9 can turn, results from it at this moment

is no effect.

If the operator now lets go of the pedal 5 and this consequently returns to its rest position, the relay 36 remains closed via its closed Switching contact 39 and the contact brushes 31 and 33 of the Control roller 24 energized as long as the needle of the sewing machine has not yet reached its deep silage. By the return of the pedal! " in the rest position, the clutch disc 10 is pulled off the friction disc 6 and places si <* h against the friction disk 7 of the worm wheel 8, whereby this is coupled to the intermediate shaft 9. This shaft and consequently also the main shaft 3 are consequently via the worm drive 14.8 with a reduced speed of, for example, 300 RPM, rotated When the needle is at its Reached the lowest position, the contact brush 33 leaves the Contact ring 29, whereby the hold circuit of the relay 36 is interrupted and this relay is de-energized. The changeover contact 41 thereby interrupts the circuit of the clutch winding 1) 6 and closes the circle of Brake winding 18. so that the machine is stopped immediately when the needle is in its lowest position is located.

If the operator now depresses the pedal 5 backwards, the pedal contact 44 is ge closed. This creates the circuit of the winding 43 of the control relay 42 via the contact brushes 31 and 32 of the control roller 24 and the now closed Contact 40 of the energized relay 36 is closed, whereby the relay 42 is energized and its contact 45 switches so that the circuit of the brake winding 18 is interrupted and the circuit of the coupling lungswtcklung 16 is closed. The clutch As a result, disk 19 is released again from braking element 17 and 20m Kiapphmgsorgan 15 is drawn

whereby the Maschmenwefle 3 again with the vermin which speed is driven and the needle moves from its lowest to its highest position As soon as the Na del reached this maximum level leaves the contact office ste 32 the contact ring 218 of the control roller 24 and un

SS interrupts the circuit of the relay winding 43 so that the Relaisltontakt 45 switched again win and open the circuit of the cap winding 16 and the circuit of the brake winding 18 closes. As a result, the machine is mh befmdli in the highest position

sewing needle stopped immediately.

The energization of the control relay 42 also causes the closure of the contact 46, whereby the current circle for the coil 48 of the relay 47 prepared wire during the movement of the sewing needle out of its tiel Most of the time in its highest position, the contact brush 30 lies against the contact ring 26 of the control roller 2 and thereby energizes the relay 47 briefly, so that the sen Umschahkontakt 4§ is operated. Thereby we

the previously closed circuit of the control winding 51 of the electromagnetic valve 50 interrupted and the "circuit of the control winding 53 of the Valve 52 closed so that the thread trimmer is operated in the manner described above. If that Control relay 47 is de-energized again, winding 51 is energized again by its Uirrichaltköntakt 49, see above that the thread cutter returns to its rest position.

The control circuit described above enables the operator to operate the pedal 5 in a single

for continuous movement from the foremost lowest position over the middle position to the rearmost, d. H. so move the thread trimming layer. In this case, the control relay 36 is energized first and, as soon as the Needle has reached its lowest position and thereby this: relay is de-energized, the control relay 42 is energized. Through this the clutch winding 16 remains energized, and without interruption, whereby the needle zui in a continuous movement from its lowest position zui can move the highest position in which the machine is stopped.

1 sheet of drawings

409584/1;

Claims (3)

Patent claims: 1. Sewing machine with a main clutch that can be operated forwards by depressing a pedal and a synchronizer with a control drum connected to the main machine shaft and electrically controlling an electromagnetic auxiliary clutch and braking device, by means of which the main shaft can be driven via a reduction gear at reduced speed and locked in the desired needle position in that the machine shaft can be driven via the electromagnetic clutch at reduced speed when the pedal returns to its rest position and can be locked in the lowest needle position by switching on the brake, and when the pedal is subsequently operated in the opposite direction backwards, the electromagnetic clutch can be switched on again and thus the needle with reduced Speed can be brought to its maximum position until the brake is switched on, a thread cutter being actuatable during this needle movement, marked by a pedal in the front age via a pedal contact (38) excitable first control relay (36) for closing a first excitation circuit for the electromagnetic clutch (15, 16) and a second control relay (42), the coil (43) of which with a second pedal contact (44) closed in the rearmost pedal position ), a normally closed contact (40) of the first control relay (36) and in the topmost needle position open contact (32) of the Sy ichronisators (23) is in series, whereby by exciting this second control relay (42) a second excitation circuit for the electromagnetic Coupling (15, 16) can be closed, via which the needle can be brought to its maximum position after reaching the lowest position and locked there and the thread can be severed during this movement by the thread cutter, which is electrically controlled via an additional contact (30) of the synchronizer (23) . 2. Sewing machine according to claim 1, characterized in that the first control relay (36) has a Changeover contact (41) for alternating activation of the excitation circuits of the electromagnetic Clutch (15, 16) or the electromagnetic brake (17, 18) and this with a changeover contact (45) of the second control relay (42) is connected in series, with the latter Changeover contact (45) when the second control relay (42) is excited, the second excitation circuit of the electromagnetic Coupling (15,16) can be closed. 3. Sewing machine according to one of claims 1 or 2, characterized in that the second control relay (42) has an additional switching contact (46) and via this, when the second relay (42) is energized, a third relay (47) which is actuated when the pad cutter is energized is bar, in the circuit of which the additional K clock (30) of the synchronizer (23) is located connected to the main machine shaft, an electromagnetic auxiliary clutch and braking device electrically controlled control roller, by means of which the main shaft is driven by a reduction gear with can be driven at reduced speed and locked in the desired needle position by the machine shaft being driven at reduced speed via the electromagnetic clutch when the pedal is returned to the rest position and by switching on the brake in the ίο the lowest needle position can be locked and with a subsequent Pedal actuation in the opposite direction backwards the electromagnetic clutch Can be switched on again and thus the needle with reduced speed until the brake is switched on is can be brought to its maximum position. being a thread cutter can be actuated during this needle movement