HK1094812A1 - Thread control device for a textile machine in particular for a shedding device - Google Patents

Abstract

The invention relates to a thread control device for a textile machine, in particular, for a shedding device, with at least one thread guide body ( 31 ) which may be displaced in one displacement direction by means of a positive drive ( 35 ) and in the opposite direction by means of a non-positive, pneumnatic return device ( 36 ). Me return device ( 36 ) thus comprises a cylinder/piston unit ( 64,54 ), the cylinder chamber of which ( 52 ) is connected to a compressed gas source ( 60 ) by means of a valve ( 56 ). An improvement in control is achieved when the valve ( 56 ) comprises a first valve seat ( 72 ) connected to the cylinder chamber ( 52 ) and a second valve seat ( 76 ), between which a valve body ( 82 ), provided with at least one throttle point ( 80 ), may be displaced, pre-tensioned in the rest position by means of a spring ( 84 ) against the first valve seat ( 72 ), in which the throttle point ( 80 ) is ineffective and the valve body ( 82 ) blocks the communication with the compressed gas source ( 60 ) when the valve body ( 82 ) is in contact with the second valve seat ( 76 ).

Description

Thread control device for a weaving machine, in particular for a shedding device

Technical Field

The invention relates to a thread control device for a weaving machine, in particular for a shedding device.

Background

A large number of yarn control devices for weaving looms are known. According to the closest prior art of WO97/08373, a yarn control device is disclosed which is designed with a drive and with a return device for the yarn guide part. In this case, the thread guiding element can be moved in one direction of movement by means of a drive designed as a positive drive (positive drive) and in the opposite direction of movement by means of a return device designed as a non-positive drive (non-positive) and pneumatically, which acts in the opposite direction on the positive drive (positive drive).

The pneumatic return device has a cylinder/piston assembly whose cylinder chamber is designed with an overpressure valve and with a one-way valve connected to a compressed air source. In this case, the air pressure in the cylinder chamber is set as a function of the operating state of the weaving machine. For example, during the lowest speed (cruise speed) phase, the air pressure remains lower than during the high speed phase so that the motor housing can provide the necessary power to overcome the load created by the cylinder chamber compression. In the high-speed phase, the motor delivers sufficient power so that the gas pressure can be increased further to prevent the rollers on the cam disk of the positive drive from disengaging. Furthermore, the cylinder chamber can be designed with a manually actuatable pressure relief valve to minimize the resistance caused by the compression of the cylinder chamber when the weaving machine is installed.

The disadvantage of the above-mentioned solution is that the air pressure in the cylinder chamber must be adjusted to the respective operating state. This necessitates a complicated pressure control device for setting the air pressure in the cylinder chamber, which requires a pressure reducing valve and an opening valve for activating each cylinder chamber. Furthermore, a complex electronic control of the valves is required to adjust the pressure in the cylinder chambers to the respective operating state.

For lubricating the cylinder/piston assembly, oil is dropped, for example, from above onto the piston, and, in addition to a permanent overpressure in the cylinder chamber, oil enters the cylinder chamber due to hydrodynamic effects. The oil that has accumulated in the cylinder chamber may continuously interrupt the operation of the yarn control device, since it reduces the air volume in the cylinder chamber to an undefined level, resulting in a higher, incalculable compression pressure in the chamber during operation. In the extreme case where a large part of the cylinder chamber is filled with oil, the cylinder can no longer move and continued operation of the weaving machine will lead to considerable damage.

Thus, in a modified embodiment of the pneumatic return device described in WO97/08373, the valve is designed in such a way that oil separation is possible in addition to the requirement that stable operation can be achieved. In this case, the valve is opened for several seconds at regular time intervals, allowing the oil that has accumulated in the compression space to flow out. Thus, the rollers are prevented from disengaging from the eccentric of the positive drive, but during this action (known as a maintenance cycle), the rotational speed of the loom must be reduced. At the lowest speed, the valve is also open so that the pressure in the cylinder chamber is not significantly higher than the boost pressure. Thereby, the power required by the motor is reduced, which is necessary so that the main motor can be rotated at a low rotational speed and so that manual rotation on the manual wheel can be performed without great effort.

The above solution has the disadvantage of high costs for the electric/pneumatic actuation of the valves. The entire control of the pneumatic drive of the yarn control device thus has a large number of elements, such as check valves, overpressure valves, pressure relief valves and electronic control units, which makes the system more prone to malfunction. Furthermore, the efficiency of the loom decreases due to the corresponding reduction in the motor speed for the purpose of discharging the lubricating oil, which occurs every 15 minutes. Furthermore, a reduction in the motor speed may have a negative effect on the textile quality, for example, may result in slight variations in the width of the fabric produced.

Disclosure of Invention

The invention aims to improve a yarn control device of the initially mentioned type.

Since the valve has a first valve seat connected to the cylinder chamber and has a second valve seat, a valve member provided with at least one throttle point and pre-pressed against the first valve seat by a spring can be moved between the first and second valve seats, the throttle point being inactive and the valve member shutting off communication with the compressed air source when the valve member abuts against the second valve seat, the valve can be operated in a plurality of operating states without external actuation. Furthermore, reliable oil separation is ensured by the independently operating valves without additional measures and without the need for a reduction in the rotational speed, a reduction in the maximum compression pressure in the cylinder chamber at partial loads and a reduction of the compression pressure to the boost pressure at the lowest speed.

In principle, the most different embodiments of the valve designed with two valve seats are conceivable. Hereby, the housing has two parts, wherein one part has a first valve seat at one end and the other part is designed as a closure of the housing with a second valve seat and a flow-through tube. The valve thus has a structure which is as simple as possible, which allows the valve to be manufactured economically and assembled simply.

In principle, the valve housing can have various forms. This design allows a good guidance of the piston-like valve member in the housing. Furthermore, the piston-like valve part may be provided with a sealing ring to seal the cylinder chamber outwards. It is advantageous to design the throttle point as a throttle orifice formed in the valve element. It is also conceivable to design the valve element without a sealing ring, in which case the gap between the valve element and the housing wall can be used as a throttle point.

The valve may be arranged in the connecting line between the cylinder chamber and the feed pressure chamber. However, it is advantageous to arrange it directly in the cylinder of the cylinder/piston assembly. Furthermore, it is advantageous to locate the valve at the lowest point of the cylinder. The valve can thus communicate directly with the cylinder chamber, whereby the lubricating oil which has accumulated in the cylinder chamber can be conducted along a short path through the valve into the feed pressure chamber. Accordingly, the closure of the valve is directly connected to the feed pressure chamber, in order to minimize again the flow resistance and the flow path of the outflowing oil.

In principle, the feed pressure chamber can be of any desired design, whereby the feed pressure chamber can be designed with an oil separation outlet arranged at its bottom, and whereby a connector for compressed air can be arranged on the side wall of the feed pressure chamber at a distance from the bottom of the feed pressure chamber. This arrangement of the compressed air connector and the oil separation outlet prevents oil which has collected in the feed pressure chamber from blocking the compressed air connector or flowing into the connecting line of the compressed air connector. In principle, any return device may have a separate feed pressure chamber. It is, however, advantageous to connect return devices to one feed pressure chamber. Thus, a simple construction with only one compressed air connector and one oil separation outlet for the return means is possible.

In principle, the most different designs of the pneumatic return device according to the invention can be envisaged. A particularly simple design of the valve is described, wherein the valve can be arranged at a lower point of the cylinder chamber of the cylinder/piston assembly. The lower part of the cylinder may serve as a housing for the valve. The valve space may advantageously be delimited by the cylinder inner surface, the closing part closing the cylinder chamber and the valve member and be connected directly to the compressed air source via a connector provided on the cylinder wall. A first valve seat for the valve member may be formed on the annular stop. The second valve seat may be formed in a sleeve portion of the closure portion. When the valve member is moved against the second valve seat, the cylinder chamber is shut off from the compressed air supply and the throttle point on the valve member is deactivated. Furthermore, it is particularly advantageous to provide the oil separation outlet directly on the closure.

The valve is activated as soon as the pressure in the feed pressure chamber exceeds the switching pressure. The switching pressure depends on the pressure in the feed pressure chamber and the prestress force of the spring. Hereby, the prestressing force is set from the outside, for example by means of a screw.

The maximum compression pressure of the valve can be set by the flow cross section of the throttle point. If a higher compression pressure is required, the flow cross section of the throttle point is reduced. Due to the smaller throttle area, the communication between the cylinder chamber and the compressed air source is cut off earlier, so that a higher maximum compression pressure is achieved.

The switching pressure and the maximum compression pressure in the cylinder chamber can be regulated in a simple manner.

Drawings

An exemplary embodiment of the thread control device according to the invention will be explained in more detail below for a needle ribbon loom with the aid of the drawing, in which:

fig. 1 shows a needle ribbon loom in a side view;

figure 2 shows a heald frame device with a pneumatic return device in a view transverse to the running direction of the warp yarns;

FIG. 3 shows in detail and on a larger scale the pneumatic return device shown in FIG. 2 in a home position;

FIG. 4 shows the pneumatic return device shown in FIG. 3 in a compressed position;

FIG. 5 shows another exemplary embodiment of a pneumatic return device on a larger scale;

FIG. 6 shows the pneumatic return device shown in FIG. 5 in a compressed position;

FIG. 7a shows a pressure and piston plot for a pneumatic return device according to the present invention at the lowest speed;

FIG. 7b shows a pressure and piston plot for a pneumatic return device under partial load; and

figure 7c shows the pressure and piston profile of the pneumatic return device at full load.

Detailed Description

Fig. 1 shows a needle-type ribbon loom with a frame 2 in which a main drive shaft 4 is mounted which drives at least one weft needle 6 (not shown in more detail); a reed 7; a fabric take-up device 8 and a yarn control device formed as a heald frame device 10. The needle ribbon loom has a warp beam support 12 carrying a warp beam 14, from which beam 14 the warp threads 16 are supplied to a heald frame device 10, which opens the warp threads to form a shed 18. By means of the thread supply device 20, weft thread 24 is supplied from a bobbin 22 to the weft needle 6 which introduces a weft thread loop into the shed 18. Successive loops of weft thread can be knotted to themselves or by means of a tuck thread 26 (not shown in greater detail here) supplied to the needles via a further thread supply 28 in order to knot and secure the inserted loops of weft thread.

Figure 2 shows a heald frame device 10 in which, in each case, a plurality of heald frames 30 with yarn guiding elements 31 are connected by means of a coupling 32 on the one hand via a positively driven drive 35 to a cam drive 34 and on the other hand to a pneumatic return 36. The cam drive 34 has a pivot lever 38 which cooperates with a cam 42 of a camshaft 44 at a drive point 40. At the output point 46, the pivot rod 38 is engaged to the link 32 via a joint 48. The pivot axis defined by the joint 48 runs at right angles to the plane in which the heddle frame 30 extends. The distance a of the drive point 40 of the pivot lever 38 from the respective pivot axis 50 is different among adjacent pivot levers, and the distance B of the output point 46 from the fixed pivot point 50 is also different, so that, as a whole, the heddle frames can be displaced over a range of different sizes to form a continuously widening and narrowing shed, as can be seen from fig. 1. The pneumatic return 36 is formed by a cylinder chamber 52, and a piston 54 connected to the coupling 32 is displaceable in the cylinder chamber 52 to actively compress the piston in accordance with the operating frequency of the cam driver 34. The cylinder chamber 52 is connected to a valve 56. A boost pressure chamber 58 is located forward of the valve 56 and a pressurized air source 60 is connected to the boost pressure chamber 58 to maintain air pressure in the cylinder chamber 52.

Figures 3 and 4 show the pneumatic return device in a compression action on a larger scale. In this case, fig. 3 shows the piston 54 at the top dead center 66, and fig. 4 shows the piston 54 after compression at the bottom dead center 68 of the cylinder 64. The valve housing comprises two parts: a sleeve-shaped housing 70 having a first valve seat 72 formed at one end of the cylinder chamber 52 and connected thereto; and a closure 74 having a second valve seat 76 and a flow tube 78. The communication tube 78 is connected to the boost pressure chamber 58. A valve member 82 provided with a throttle point 80 is movably arranged between said valve seats.

In the initial state shown in fig. 3, the valve element 82 is pressed against the first valve seat 72 in advance by the prestressing force of the spring 84, so that the cylinder chamber 52 and the feed pressure chamber 58 communicate with one another via the throttle point 80 in the valve element 82 and the flow-through pipe 78 in the closing part 74. Under high pressure conditions of the cylinder chamber 52, the valve member 82 moves against the second valve seat 76 and blocks communication between the cylinder chamber 52 and the boost pressure chamber 58, as shown in FIG. 4. In this position, the throttle point 80 is not active.

The compression/expansion action of the cylinder/piston assembly will now be described with the aid of figures 3 and 4 in conjunction with the diagrams in figures 7a, 7b and 7 c. In the graph, H represents the stroke of the piston of the cylinder/piston assembly, where UT is bottom dead center, OT is top dead center, and PK represents the air pressure in the cylinder chamber. PS represents the necessary switching pressure so that the valve member switches from the first valve seat to the second valve seat or vice versa. The switching pressure PS can be divided into a propulsion pressure PD of the compressed air source and a corresponding pressure PF of the spring force. In this case, VZ represents the position of the shut valve, and VO represents the position at which the valve communicates with the cylinder chamber via the throttle point.

First, the piston 54 moves downward from the apex in the cylinder 64, and at the same time, in a first stage, moves air to the propulsion pressure chamber 58 through a throttle point 80 formed on a piston-like valve member 82. As the piston velocity increases, the pressure differential across the valve member 82 (PK-PD) rises until the switching force generated on the valve member 82 by the cylinder chamber pressure PK overcomes the pre-stressing force of the spring 84 and the force generated on the valve member 82 by the motive pressure PD and presses the valve member 82 towards the second valve seat 76. The throttle point 80 of the valve member 82 is no longer functional. By moving the piston 54 further towards the valve 56, the cylinder chamber pressure PK rises sharply during the compression action of the cylinder chamber 52 and reaches its maximum value at bottom dead center UT. In the expansion phase, the valve member 80 moves from the second valve seat toward the first valve seat 76 once the spring force exceeds the force generated on the valve member 80 by the pressure differential (PK-PD). At the end of the expansion phase, corresponding to the top dead center 66 of the piston, a boost pressure PD is generated in the cylinder chamber. In addition, any oil that has accumulated in the cylinder chamber 52 may exit through the flow-through tube 78. In the following compression action, the outflowing oil is blown out by the air displaced into the feed pressure chamber 58 and flows out in an oil separation outlet 88 formed on the bottom 86 of the feed pressure chamber. A connector 90 for compressed air is provided on a side wall 92 of the propulsion pressure chamber to prevent further back flow of oil.

Fig. 5 and 6 show on a larger scale a further design variant of the pneumatic return device in the compression action. In this case, fig. 5 also shows the piston 54 at top dead center 66, and fig. 6 shows the piston 54 at bottom dead center 68 in the cylinder 64 after compression of the cylinder chamber 52. The valve 56a is also disposed directly at the lowest point of the cylinder 64. In this case, the cylinder wall functions as a valve housing, and the valve space 94 is defined by the wall of the cylinder 64, the closing portion 74a closing the cylinder 64, and the piston-like valve member 82 a. A stop 71, designed as a ring, is arranged directly in the cylinder 64 of the cylinder/piston assembly and serves as a first valve seat 72a for a piston-like valve part 82 a. The valve member 82a is also pressed against the first valve seat 72a in advance by the spring 84 a. In this case, the spring 84a is supported on a closure part 74a, which closure part 74a closes the cylinder and has an inner sleeve part 96 for guiding the spring 84a, and furthermore, the free end of this inner sleeve part 96 serves as the second valve seat 76a of the valve element 82 a. When the valve member 82a abuts against the second valve seat 76a, the throttle point 80a formed in the valve member 82a does not function. Also in this position, the connector 90a for the compressed air source 60 arranged on the cylinder is blocked by the valve member 82 a. The oil collected in the cylinder chamber 52 can flow out via the oil separation outlet 88a formed on the closing portion 74 a.

In the initial state depicted in fig. 5, the valve member 82a is pre-pressed against the first valve seat 72a by the pre-stressing force of the spring 84a, so that the cylinder chamber 52 is connected to the compressed air source via the throttle point 80a in the valve member 82 a. Under high pressure conditions of the cylinder chamber 52, the valve member 82a moves against the second valve seat 76a and shuts off communication between the cylinder chamber 52 and the compressed air source 60 by blocking the connector 90a provided in the cylinder wall, as shown in fig. 6. In this position, throttle point 80a is not active.

At the end of the expansion phase, a boost pressure is created in the cylinder chamber 52. Any oil that collects in the cylinder chamber 52 may flow out through the throttle point 80a into the valve space 94. In the next compression action, the outflowing oil is blown out by the air displaced into the valve space 94 and flows out in the oil separation outlet 88a formed on the bottom 98 of the closing portion 74 a. A connector 90a for compressed air is provided on the cylinder wall 100 at a distance from the bottom of the closing part, thereby preventing further backflow of oil.

Fig. 7a, 7b and 7c show the pressure and piston profiles of the return device according to the invention at the lowest speed for two load cycles for a speed of 800 revolutions per minute (fig. 7a), a partial load at 1000 revolutions per minute (fig. 7b) and a full load at 4000 revolutions per minute (fig. 7 c).

At operating speeds from the lowest speed to, for example, 800 rpm (fig. 7a), continuous pressure compensation takes place via the throttle point of the valve member, so that the cylinder pressure PK does not reach the switching pressure PS necessary to cut off the communication between the cylinder chamber and the compressed air source. Thus, the pressure PK in the cylinder chamber is always in the order of magnitude of the boost pressure PD. The motor load due to the pneumatic drive is thus low and allows the motor to run quietly and, in particular, the drive is switched off and the yarn control device is moved manually for, for example, setting and repair purposes.

At a partial load of 1000 rpm (fig. 7b), the cylinder chamber pressure PK reaches the necessary switching pressure PS in one cycle, whereby the valve cuts off the communication of the compressed air source and the cylinder chamber and starts the compression in the closed cylinder chamber. The compression of the cylinder chamber reaches its maximum at bottom dead center UT. In a subsequent expansion, the cylinder chamber pressure PK falls below the switching pressure PS again. The cylinder chamber is then connected again to the compressed air source and when the piston reaches the top dead center OT, the boost pressure PD is built up again in the cylinder chamber. The compression pressure in the cylinder chamber prevents the roller from disengaging from the eccentric of the positive drive at higher operating speeds.

The necessary switching pressure PS is reached earlier at full load of 4000 revolutions per minute compared to the lower operating speed (fig. 7 c). Thus, compression occurs over a larger stroke and thus the maximum compression pressure reaches a larger value than at lower operating speeds. During the subsequent expansion, the necessary switching pressure PS is reached again, whereby the valve resumes communication of the cylinder chamber and the compressed air source. The maximum compression pressure is a direct function of the machine speed, i.e. the higher the speed, the higher the maximum compression pressure increases. This is beneficial for efficient operation of the machine and proper functioning of the positive drive.

By opening the valve once per working cycle, the lubricating oil that has accumulated in the cylinder chamber is continuously drained. Thus, the apparatus can be operated reliably and continuously without any maintenance cycle of removing lubricating oil from the cylinder chamber. The tasks and requirements of the valves described above are performed independently, that is, without any external actuation. The spring force, the throttling cross-section and the outer diameter of the valve member or the diameter of the valve seat are dimensioned to provide the independent control function of the valve.

The return device for a thread control device described here thus independently meets the maximum deformation requirements and at the same time has the smallest possible cost on a technical level. The return device can thus be produced particularly economically and, owing to its simple construction, is largely maintenance-free and trouble-free during operation.

The thread control device according to the invention can also be used in individual thread controllers of, for example, jacquard machines and, in addition, in weft thread devices for supplying individual weft threads.

List of reference numerals

2 frame 56a valve

4 main drive shaft 58 boost pressure chamber

Compressed air source for 6 weft needle 60

7 reed 64 cylinder

8 top dead center of the fabric winding device 66

10 heald frame device 68 bottom dead center

12 warp beam support 70 housing

14-beam 71 stop

16 warp 72 first valve seat

18-shed 72a first valve seat

20 yarn supply 74 closure

22 spool 74a closure

24 weft yarn 76 second valve seat

26 coil collector wire 76a second valve seat

28 yarn supply device 78 communicating tube

30 heald frame 80 throttle point

31 thread guide part 80a throttle point

32 coupling 82 valve member

34 cam driver 82a valve member

35 positive drive driver 84 spring

36 return 84a spring

38 pivot rod 86 bottom

40 drive point 88 outlet

42 cam 88a outlet

44 camshaft 90 connector

46 output point 90a connector

48 wall of joint 92

50 pivot axis 94 valve space

52 cylinder chamber 96 sleeve portion

54 bottom of piston 98

56 valve 100 wall

Claims (20)

1. A yarn control device for weaving machines, with at least one yarn guiding element (31) which is movable in one direction of movement by means of a drive (35) designed as a positive drive and in the opposite direction of movement by means of a return device (36) designed as a non-positive drive and pneumatically, which return device (36) has a cylinder/piston assembly (64, 54), the cylinder chamber (52) of which is connected to a compressed air source (60) via a valve (56, 56a), characterized in that the valve (56, 56a) has a first valve seat (72, 72a) connected to the cylinder chamber (52) and has a second valve seat (76, 76a), between which a valve element (82, 82a) provided with at least one throttle point (80, 80a) is movable, which in the original position is moved by means of a spring (84), 84a) is pre-pressed against the first valve seat (72, 72a), when the valve member (82, 82a) abuts against the second valve seat (76, 76a), the throttle point (80, 80a) is deactivated and the valve member (82, 82a) shuts off communication with the compressed air source (60).

2. Yarn control device as in claim 1, characterised in that the valve has a housing (70) and that the first valve seat (72) is formed at one end of the housing.

3. Yarn control device according to claim 2, characterised in that the second valve seat (76) is formed on a closing part (74) designed with a flow duct (78).

4. Yarn control device as in claim 2 or 3, characterised in that the housing (70) is designed cylindrically, in which the piston-like valve element (82) is guided and closed off with respect to the housing wall.

5. Yarn control device as in claim 2 or 3, characterised in that the gap between the valve element (82) and the housing wall of the valve (56) serves as a throttle point.

6. Yarn control device according to claim 1 or 2, characterised in that a valve (56, 56a) is arranged in the cylinder chamber (52).

7. Yarn control device according to claim 1 or 2, characterised in that the valve (56, 56a) is arranged at the lowest point of the cylinder (64).

8. Yarn control device according to claim 1 or 2, characterised in that the closing part (74) of the valve (56) is directly connected to the feed pressure chamber (58).

9. Yarn control device as in claim 8, characterised in that the feed pressure chamber (58) has an oil separation outlet (88) for oil from the cylinder chamber (52).

10. Yarn control device according to claim 9, characterised in that an oil separation outlet (88) is provided at the bottom (86) of the feed pressure chamber (58).

11. Yarn control device as in claim 10, characterised in that the connector (90) for compressed air is arranged on a side wall (92) of the feed pressure chamber at a distance from the bottom (86) of the feed pressure chamber (58).

12. Yarn control device as in claim 8, characterised in that the feed pressure chamber (58) of at least one return device (36) serves as feed pressure and oil outflow means.

13. Yarn control device according to claim 1, characterised in that the lower part of the cylinder (64) serves as a valve housing and has a connector (90a) for a compressed air source (60).

14. Yarn control device according to claim 13, characterised in that the annular stop (71) is arranged inside the cylinder (64) and is arranged to be connected to the first valve seat (72a) of the cylinder chamber (52).

15. Yarn control device according to claim 14, characterised in that the cylinder (64) is closed by a closing part (74a), the closing part (74a) having a sleeve part (96), the free end of which serves as the second valve seat (76 a).

16. Yarn control device according to claim 15, characterised in that the oil separation outlet (88a) is provided on the closure (74 a).

17. Yarn control device according to claim 1, characterised in that the switching Pressure (PS) of the valve (56, 56a) is set by varying the prestress force of the spring (84, 84 a).

18. Yarn control device as in claim 17, characterised in that the prestress force of the spring (84, 84a) is set from the outside.

19. Yarn control device as in claim 1, characterised in that the maximum compression Pressure (PK) in the cylinder chamber (52) is set by the flow cross section of the throttle point (80, 80 a).

20. Yarn control device as in claim 1, characterised in that the yarn control device is for an opening device.