DE1901639A1 - Pneumatic drive for thread cutting devices of sewing machines - Google Patents

Description

SpA VIRGIUIO RIIIOLDI & C.
Via Veapri Sicilian! 9
20146 Milan / Italy

Patent application

Pneumatic drive for thread sill devices from

Ilähma machines

The invention relates to a pneumatic drive for thread sons of sewing machines.

In general, the sewing machines equipped with a thread cutting device are also provided with means to stop the machine at either the lowest or highest needle position. This means include an electric drive motor and a clutch switch arm for coupling the machine to the Engine,

In a machine of the type mentioned above, there is a shortcoming that the thread cutting device in Activity must be set if either the machine has not yet stopped or the needle is still is not exactly in its uppermost position, as a result of which it can often happen that the cutting knife come into contact with the IT needle during its working stroke and break or damage it in the process.

Furthermore, there is a disadvantage with the machines mentioned that the thread cutting device possibly resumes its activity without a few sewing stitches having been carried out in between, which leads to As a result, the threads slip out of the thread clamp or are unthreaded from the stitch-forming tools when the sewing work is resumed will.

You invention has set itself the task of this ! laughable parts by eliminating the errors shown to avoid·

Therefore, the technical problem to be solved is the creation of a pneumatic drive for the Thread cutting devices equipped with a safety device to avoid premature cutting activity is provided, which also serves to prevent the repetition of this activity, as long as not in the In the meantime, a few sewing stitches have been carried out in order to prevent damage to the machine or the cutting knives.

According to the invention, this technical one becomes a solution Problem provided a pneumatic drive device that mechanically with the clutch release lever of the Electric motor is connected and further on the one hand with an air supply line and on the other hand with a control device for controlling the Needle position and is in communication with an auxiliary compressed air tank. This container is in turn with connected to an air cylinder provided with a return spring via a distribution valve which is operated by the control device. The pneumatic drive device serves to supply the auxiliary container with compressed air charge when the machine is running and the activity initiate the control device when the machine is using

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- 3 the Iladel in-iüer © "burst position is stopped.

The. Steuererrorrichttmg is like that. rubbed in that they the distribution valve "actuates to the compressed air that is in the auxiliary air reservoir "is located in the one with the return spring equipped air cylinder to flow. Take up compressed air, which is sufficient to operate the air cylinder, which works with the return spring, once for every 1, 'aiivorgang to make work as this air cylinder to. drive der_Fadenschneidvorrichtung the sewing machine is provided.

The main advantage of this pneumatic drive is that a single _; Thread cutting process is provided for each sewing process in order to ensure the exact stitch execution when the sewing machine is restarted. Another advantage of the pneumatic drive consists in the elimination of every electrical element from the drive of the thread cutting device, which is composed entirely of pneumatic elements. From this derives the possibility of equipping the sewing machine with an electric motor of any type, provided that this motor is provided with a device for adjusting the fault. Therefore, the electrical circuits of this device do not need transformers, which are otherwise required to drive the thread trimmers, because the sequence of operations of the thread trimmers is completely different from that of the needle setting device. .

Other objects and advantages of the present invention result from the following detailed description of a preferred embodiment and the attached Drawings showing:

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809886/0916

Fig. 1 shows schematically the drive according to the invention;

Fig. 2 shows an enlarged sectional view of the pneumatic drive device}

Fig. 3 shows a flywheel of the sewing machine with which the control device for the! Tadel position in Intervention can occur;

4 and 5 show enlarged views of the control device, partly in cut.

1 shows a sewing machine 10 with a thread cutting device, not shown in the drawings, which is provided with a device for cutting and clamping the needle and looper thread at the end of a sewing process after the needle is automatically in its uppermost position accordingly the top dead center position has been set ₀

The sewing machine 10 is driven by an electric motor 11 which is provided with the usual means for maintaining the optional loading positions. The electric motor 11 has a coupling device, from which a coupling lever 12 can be seen on the outside, which is used to couple the rotor of the hotors to a drive pulley 13 in order to drive the sewing machine 10 by a conventional drive belt 14 and a driven pulley 15. The connection between the driving disc 13 and the rotor is effected by moving the clutch lever 12 downward by means of a switch which, for. B. can be provided in the form of a conventional pedal plate 16. The mechanical connection between the clutch lever 12 and the foot switch consists of a first rod 17, the lower end of which is articulated to the front part 18 of the pedal plate and the upper end of which is arranged in a support arm 19, on which a second rod 20 can be freely moved upwards attached is _T t,

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At the upper end the rod 17 is provided with a pair of nuts 21 to the sliding of the rod of the bracket 19 to prevent _f when the stepping plate 16 is depressed 17th A hand- or foot-operated three-way valve 22 of a pneumatic drive device 23, which represents the essential part of the drive, is arranged on the support arm 19.

The three-way valve 22 comprises a cylinder in which a spring-loaded piston 24 is displaceably housed, which is provided with a rod 25 protruding from the bottom of the cylinder and which is supported against an adjusting ring 26 on the first rod 17. In the cylinder, a return spring 27 is provided, which serves to hold the piston 24 in its rest position, in which a line 28, which is connected to an air supply line 29, with a line 30 of a normally closed valve 31 of the pneumatic drive device 23 in Connection.

This valve 31 has a cylinder which is attached to the upper end of the second rod 20 and in which a spring-loaded piston 32 slides, which is provided with a rod which is articulated on the clutch lever 12. Between the piston 32 and the upper wall of the cylinder of this valve 31 is a return spring 33, the tension of which is slightly greater than that of the return spring, not shown, of the clutch lever 12. This arrangement is made so that the clutch lever 12 is pulled down "before the spring-loaded piston 32 is moved in the cylinder of the normally closed valve 31. In addition, the return spring 33 serves to hold the piston in its own rest position bu, in which the outlet of the line 30 connecting the three-way valve 22 to the normally closed valve 31 connec det, is closed in such a way that an air passage

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BATH ORIGINAL

- 6 is not possible through line 34 "

From the air supply line 29 there is another line 35 , from which compressed air is fed into the needle adjustment control device 36 and is also passed through a line 37 into a distribution valve 38 which is directly connected through the lines 39 and 40 to the thread cutting device of the sewing machine . From the supply line 29 establishes the compressed air is introduced into the control device 36 and holds therein a piston 41 in its rest position "The pressurized air also enters the distributor valve 36, flowed from which it into the duct 39" with the appropriate setting of the Doppelkorbens 42

Finally, the compressed air flows from the line 39 through the thread cutting device in such a way that it is held in a safe or rest position. The position of the double piston 42 depends on the action of a spring 43 which presses on the piston 44 of an air cylinder 45, the piston 44 being connected to the double piston 42 by a rod.

When the front part 18 of the settee 16 is depressed, the clutch lever 12 is also depressed and the sewing machine 10 starts to work. If the pedal plate 16 is pressed further, the clutch lever the end of its stroke is reached and the tension of the return spring 33 is overcome. As a result, the cylinder of the normally closed valve 31 is moved relative to the spring-loaded piston 32, whereby the lines 30 and 34 are connected to one another.

As a result, the compressed air is free to be charged of the auxiliary tank 47 by removing the air from the supply

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Line 29 through line 28, the three-way valve 22 and lines 30 and 34 flows.

The auxiliary container 47 is used to hold a sufficient amount Ilenge compressed air to push piston 44 of the To let air cylinder 45 slide against each 43, the auxiliary tank 47 with this cylinder 45 through a line 4 &, a distribution valve 49 of the control device. 36 and connected by a line 50.

At the end of an IlälivorgangeB the pedal plate 16 released and returns to its rest position as a result of the combined action of the liücki'Uhrf eder of the clutch ehalt hebeis 12 and the return spring 33 of the normally closed valve 31 back. As a result, returns the spring-loaded piston 32 is also in its upper position back and closes both the access to the line 34 and ziim auxiliary container 47, the compressed air is loaded.

In the meantime, the sewing machine 10 has been stopped with the "cue" in its lowest "position. This position is automatically brought about by a suitable electrical circuit, as mentioned above. In this operating position, the sewing machine can be restarted or the thread cutting device can be activated for cutting as required ₀

If the thread cutting device is to be put into operation, this is done by moving the pedal plate 16 reached in the opposite direction, namely by depressing the rear part 51 of the pedal plate 16. This Pedal plate movement mainly corresponds to the reversal of the needle setting by pressing a suitable one Switch of the electrical circuit, which is not shown and is combined with the pedal board, as well as the lifting of the front part 18 and the first

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Rod 17, which slides freely in the support arm 19, which itself is not moved _o The sliding of the first rod 17 moves the adjusting ring 26 against the push rod 25 ₉ which is adjusted together with the spring-loaded piston 24 against the action of the return spring 27. This piston closes the passage of the compressed air from the line 28 to the line 30 and at the same time opens the passage of the compressed air from the line 28 to a line 52, which connects the three-way valve 22 to the control device 36 and compressed air enters the other side of the piston 41 leaves. As a result, the piston 41 is pushed to the right, while the line 35 discharges the compressed air contained in the cylinder into the atmosphere _{or the like}

Thus, the work of the thread cutting device can take place only when the lladel is stopped in its uppermost position, is a flywheel 531 which is provided with a slot 54, the sewing machine 10 keyed to the main shaft 55 (see Fig _{3: 0) 0} This slot 54 , which has a certain angular extent, is related to the sewing machine needle in such a way that it lies transversely to the path of a push rod 56 of the control device 36 (see also FIGS is provided with a spring which is mounted on a bolt 57. The bolt 57 is carried by a plate 58 which is attached to a rod 59 of the piston 41. When the piston 41 is pushed to the right by the compressed air flowing in through the line 52, the push rod 56 reaches the flywheel 53 and comes into engagement with the slot 54 when this is set across the path of the push rod 56. In this case, the piston performs its full stroke from _e If the! Censure is not accurately adjusted according to their top dead centers, the slot 54 is not transversely in front of the way of the push rod 56, which then abuts against the flywheel body and prevent

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changes that the piston 41 executes its full right-hand stroke. The angular extent of the slot 54 has such an extent that it allows only one needle position deflection ύοπ - 1 μ.

Since the piston 41 is connected to a piston 60 which is slidably housed in the distribution valve 49, the passage of compressed air from the line 48 to the line 50 depends on the magnitude of the stroke that the piston 41 makes to the right. For this reason, the passage is only possible when the needle is in its uppermost position and conversely, the passage is not possible when the push rod 56 strikes the flywheel body, which corresponds to an imprecise needle position. When the piston 41 has completed its entire stroke to the right, the compressed air in the auxiliary container 47 can reach the cylinder 45, which operates with a back-up spring, and then move the piston 44 against the action of the spring 43. The piston 44 is displaced and moves the double piston 42 of the distribution _{valve 38, which connects the line 37 with the line 40 o} Daduroh, the effect of the compressed air on the thread cutting device, which carries out the first phase of its working cycle, is also reversed.

As soon as the compressed air contained in the auxiliary container 47 has completely escaped, the spring 43 pushes against the Piston 44, which moves the double piston 42 into its rest position, in which it allows the passage of the compressed air from the Line 37 only restores line 39. The second phase of the work cycle corresponds to this process Fadensohneidvorriontung, d. H. to the sons and clamps the needle and looper thread.

All of these operations take place simultaneously as Result of the action that is exerted on the footplate 16, which are therefore released immediately afterwards

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can. When the cret plate is released, the presses Return spring 27 moves the piston 24 to its rest position and thereby interrupts the passage of the compressed air of the line 52 and also provides the passage of the compressed air to line 30 again. The compressed air contained in the line escapes directly into the atmosphere. The piston 41 can then be moved into its rest position thereby disengaging the bumper 56 from the flywheel slot 54.

A resumption of the thread cutting process is no longer possible, since the auxiliary container 47 is completely discharged is. However, it is not possible to recharge the auxiliary container before the normally closed one Valve 31 is moved. But this movement is also synonymous with the coupling of the ITewing machine the engine. Therefore, the sewing work can only begin each time when the I-needle and looper threads are clamped by the thread cutting device, and therefore i3t the process of cutting these threads is only possible after a few sewing stitches have been performed.

The rightward stroke of the piston 41 and the Bumper 56 is opposite the loading setting by a throttle valve 61 in line 52 is delayed. This throttle valve is used to slowly bring in compressed air admit the cylinder of the control device 36, so that the entire right-hand stroke of the piston 41 »namely at Engagement of the push rod 56 in the slot 54, is only completed after the ITadel after the shutdown of the sewing machine is set correctly.

Another unfavorable condition in addition to the imprecise handle position can be caused by lifting the Press the presser foot of the sewing machine. For this reason, a presser foot lifting device is provided which in front of the inlet pipe of the compressed air supply line 29

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is ordered and consists of a three-way push valve 62, which is operated by a suitable switch, e.g. 13ο by a knee-moved switch 63ο

This three-way plunger valve, which is permanently held in a rest position by a peder 64, sees one Compressed air passage from the inlet tube 65 to the delivery line 29 by means of a double piston 66, which can be adjusted accordingly. If that pressed by the knee Switch 63 is moved in the direction of arrow A. is, the piston 66 is pushed to the right in such a way that the passage of compressed air to the Compressed air supply line 29 is interrupted, whereby this part of the pneumatic switching device is put out of operation with the part 23 of the pneumatic Drive is connected. On the same side, the passage of the compressed air to a line 67 is opened, which is connected to a cylinder 68, the piston 69 of which is connected to the presser foot 70 of the sewing machine 10 connected is.

The compressed air, which enters in this manner in the provided with • return spring air valve 68 causes the sliding of the piston 69 against the action of a Peder 71 and tends to raise as a result of the presser 70 _o At the end of exposure to the knee switch 63 compresses the spring 64 the piston 66 in its rest position and brings the mentioned part of the pneumatic drive device ready for operation again.

A modified embodiment of the pneumatic drive device 23 (see Pig. 2) consists of a normally closed valve 31 for charging the Auxiliary air tank 47 with compressed air and from a three-way valve 22 for actuating the control device 36 for the loading adjustment, both in a single cylinder

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Aryan carrier 72 are housed. In this vehicle

72 are two threaded rods 73 and 74 resiliently slidable, the ends of which protrude from the cylindrical support _a The rod 73 of the normally closed valve 31 is connected to the clutch lever 12 of the electric motor 11 and is inserted into the interior of the support 72 by a return spring 75 pushed, which presses with its one end against the wall 76 of the carrier 72 and with its other end against an annular stop 77 with which the rod is provided and which serves as a stroke limiter. This pole

73 is also provided with a shaft 78, the one Part 79 has a smaller diameter than the shaft »This part is used to connect a line 80 with a To connect line 81 with which the carrier 72 is provided.

The line 80 is connected to the auxiliary air tank 47, while the line 81 with the air supply line 29 is connected. In the rest position of the rod 73, the two lines 80 and 81 are not with one another tied together. In the shaft 78 an axial bore 82 is provided, which in a radial hole 83 on the outside of the part 79 opens. The rod 74 of the three-way valve 22 can be connected to the pedal plate 16 in a similar manner to the first rod 17. It is usually to the outside of the carrier 72 through pulled a return spring 84, which with one end against an intermediate wall 85 of the carrier and with the other End presses against a ring-shaped stop 86 on the rod, which prevents the rod 74 from the carrier 72 slides out.

The rod 74 is provided with a shaft 87 which protrudes into the interior of the carrier 72 and three intermediate parts 88, 89 and 90 of smaller diameter. The part 88 serves to through an outlet 91 the

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in the line 92, which is connected to the control device 36, such as the line 35 of FIG. 1, is connected to release existing compressed air into the atmosphere. The part 89 is provided with a radial hole 93 in connection with an axial bore 94-, which in turn is in connection with the axial bore 92 of the rod 73. The part 89 serves to selectively in the line 92 or to the line 95, which is connected to a control device 36 in a similar manner as the line 52 of the Ji ¹ Ig ₀ 1.

Finally, the part 90 serves to connect the line 95 to the atmosphere through an outlet 96 when the rod 74 is in its rest position. As carried out in the pneumatic drive device 23 of FIG. 1, when the front part of the pedal plate 16 is depressed, the clutch lever 12 is also depressed, so that when this movement continues, the rod 74 and the carrier 72 are pulled downwards like a piece, while the Rod 73 is held. The displacement of the carrier 72 with respect to the rod 73 causes the compression of the spring 75 and the adjustment of the part 79 with respect to the lines 80 and 81, which are in this way connected to one another. The compressed air flows freely from the line 81 to the line 80 and from there to the auxiliary air tank 47.

When the footplate 16 is released, which corresponds to the shutdown of the sewing machine, the spring 75 expands again. It brings the rod 73 back into its rest position and once again interrupts the passage of the compressed air from the line 81 to the line 80. If the rear Tgü 51 of the footplate 16 is now depressed, the rod 74 is lifted upwards against the action of the spring 84, while the carrier 72 stands still because the annular stop 77 of the rod 73

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prevented its movement The relative displacement between the support 72 and the rod 74 causes the adjustment of the part 88 with respect to the line 92 _o In this case, the compressed air that is in this line 92 and through the line 81 and through the holes 83, 82, 94 and 93 had been supplied to keep the control device 36 in its rest position, released through the outlet 91 into the atmosphere.

At the same time the part 89 is opposite the line 95 ₉ which is connected to the line 61 of the compressed air supply. This compressed air is sent into the cylinder of the control device 36 on the other side of the piston 41, which is thereby pushed to the right, and _0, the rod 56 moves, the movement of the member 90 is unbeaohtlich since it here leads to no specific action.

When the depression of the pedal board is completed, the spring 84 expands and brings the rod 74 in place back to its rest positiono moved as a result the part 38 away from the line 92 and closes the Air passage to the atmosphere. The part 89 is again opposite the line 92, which is compressed air receives and so the return of the bumper 56 to its rest position causes. Finally, the part 90 is set opposite the line 95, which it connects to the outlet 96, through which the air contained in the line 95 escapes into the atmosphere, so that the bumper 56 can return.

Expectations;

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Claims (1)

Expectations 1e Pneumatic drive for Badenscimeidvorrichtungen of sewing machines with a device for stopping the machine "at the lowest:.: Or the highest ITadeletand, this device having an electric drive motor and a clutch lever for coupling the cabinet with the motor, characterized in that a pneumatic drive device (25), which is mechanically connected to the clutch shift lever (12) of the electric motor (11), on the one hand with a compressed air supply line (29) and on the other hand with a control device (36) for controlling the load distribution, and with an auxiliary air tank (47 which is actuated by the control device (36) from being connected) which for its part cylindrical with a eäer with Hückstellf verseheneii air (is 45) via a distributor valve (49) in communication, _s further that the pneumatic drive means (23) serves to the Charge auxiliary container (47) with compressed air when the sewing machine (10) is running, and the control Device to be operated when the sewing machine is stopped with the needle in the highest position, the control device (36) actuating the distributor valve (49) in order to supply the compressed air contained in the auxiliary container (47) to the air cylinder (45) provided with a return spring guide, and that finally the auxiliary air tank (47) only absorbs as much compressed air as is sufficient for a single actuation of the air cylinder (45) for each sewing process, this cylinder (45) ζυψ drive the thread cutting device of the ITähma machine (10) di ent _o 2o pneumatic drive according to claim 1, characterized characterized in that the drive device (23) is a usually closed valve (31) and a three-way valve (22), both of which are mounted in the same carrier (19, 72), and mechanically with the clutch shift lever - 16 909886/0916 ^ ⁰ ° * ®I (12) and a switch (16) operated by the cock, which is provided for the clutch shift lever (12), whereby the movement transmitted to the clutch lever (12) is also transmitted to these two valves (22, 31), that, furthermore, the normally closed valve (31) "is used to charge the auxiliary reservoir (47) with compressed air when the clutch lever (12) is moved to the llähmaschinenantriebsstellung _f and that the three-way valve (22) the control device (56) drives, when the machine ( 10) is stopped and its reproof is in the highest position after the switch (16) actuated by the cockerel has been moved in the opposite direction, 3. Pneumatic drive according to claim 1, characterized in that the control device (36) for controlling the fault position has a cylinder in which a sliding piston (41) is accommodated, which is provided with a push rod (56) and with another Piston (60) of the distribution valve (49) is connected, that also the control device (36) with the pneumatic. see drive device (23) through separate lines (35, 52; 92, 95) is connected to compressed air either on one side of the piston (14) of the control device (36) to get and to keep the piston (41) in its rest position when the machine (10) is running, or on the other side, thereby moving the piston (41), when the machine (10) with the Iladel in the highest position is stopped that further the bumper (56) with a slot (54) of a flywheel (53) in engagement can occur, this slot (54) being related to the rebuke in such a way that it is opposite the path of the The bumper (56) is when the needle is in its top dead center, and finally the piston (60) of the distributor valve (49) serves to connect its lines (48, 50) with each other and thus the auxiliary air tank (47) with the to connect the cylinder (45) provided with a return spring, - 17 909886/0916 thus compressed air from one line (48) to the other (50) can arrive when the basket (41) of the control device (36) has performed its full right-hand stroke and the bumper (56) has entered the slot (54) and, conversely, serves to facilitate the passage of the Compressed air from one line (48) to block the other (50) when the piston (41) of the control device (36) is in its rest position or if it has not fully performed its return stroke, 4. Pneumatic drive according to claim 2, characterized in that the pneumatic drive device (23) is connected in its lower part to the switch (16) actuated by the Ilaherin by a first rod (17) is, & which can be moved upwards in a support arm (19) is mounted, to which the three-way valve (22) and a second rod (20) are attached, the upper part of which carries the normally closed valve (31) which is articulated on the clutch release lever (12), the first rod (17) for transmitting the movement of the switch (16) actuated by the seamstress and simultaneously to operate the normally closed valve (31) during the holder movement in one direction serves and also to actuate the three-way valve (22), and that for this purpose the rod (17) freely in the support arm (19) during the movement of the so holder (16) can slide in the opposite direction. 5 * Pneumatic drive according to claim 2, characterized in that that the drive device (23) with the clutch lever (12) through the normally closed Valve (31) is connected, which has a rod (73) which is resiliently by a return spring (75) in the interior of the carrier (72) is pressed and is provided with a shaft (78) which has a part (79) of smaller diameter than the shaft and bores (82, 83) which are connected under sioh, and that the carrier (72) also - 18 909886/0916 with the switch (16) operated by the IT seamstress durA the three-way valve (22) is connected, which has a rod (74) which is resiliently supported by a return spring (84) is pressed against the outside of the carrier (72), this rod (74) having a shaft (87) which with Parts (88, 89, 90) of smaller diameter and with bores (93, 94) are provided, which one below the other and with the bores (83, 82) of the first rod (73) are connected, that also the part (79) of the first rod (73) is used to connect two lines (80, 81) to one another and to load the auxiliary container (47), if the clutch lever (12) is moved in one direction by the switch (16), and the part (89) the second Rod (74) is used to let compressed air into a line (92) to control the control device (36) to keep the loading position in the rest position, and To let compressed air into another line (95) to operate the control device when the switch (16) is moved in the reverse direction while the thinner parts (88, 90) of the second rod (74) to discharge the compressed air in the associated lines (92, 95) into the atmosphere when these lines are not in connection with the line (81) which is connected to the compressed air supply line (29) via the bores (81, 83, 93, 94) of both rods (73, 74) is connected. 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