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(11) | EP 1 264 924 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Hydraulic control circuit for a fabric treatment jigger |
| (57) Hydraulic control circuit for a Jigger type fabric treatment machine (10) where a
roll (20) of fabric (18) is unwound by an uncoiler reel (14 or 16) and where the fabric
itself (18) is guided into a tank (12) containing a treatment bath, before being rewound
on a coiler reel (16 or 14) to form a roll (21) of treated fabric (18) and vice versa,
the reels (14, 16) being operated by hydraulic motors (24, 26) connected via branches
(34, 36; 34', 36') of the hydraulic circuit to a pump (28), where the hydraulic circuit
is of the closed type, a brake valve (40) being also provided which exerts a variable
back pressure on the motor during braking (24 or 26). |
[0001] The present invention concerns a hydraulic control circuit for a Jigger type fabric treatment machine.
[0002] In the textile sector, Jigger type machines are used, for example, to dye or bleach fabric in a roll in natural or artificial fibre.
[0003] A machine of this type consists basically of a tank designed to contain a treatment bath above which an uncoiler reel and a coiler reel are positioned.
[0004] The fabric, which is wound to form a cylindrical roll, is loaded onto the uncoiler reel of the machine by means of a trolley. As the beginning of the fabric unwinds from the trolley, it is conveyed along a fixed course defined by rollers and rockers into the treatment bath, which is empty at this stage, and wound onto the coiler reel.
[0005] After this first operation, the tank is filled with the treatment bath consisting of various chemical products dissolved in a liquid.
[0006] Once the tank has been filled, the treatment phase can begin consisting in unwinding the fabric from the uncoiler reel and winding it onto the coiler reel. The strip of fabric becomes impregnated with the substances present in the bath as it passes through.
[0007] Shortly before the fabric on the uncoiler reel comes to an end, it is possible to stop the machine and invert the rotation direction of the two reels. In this way the fabric is fed through the bath a second time. At the end of the second run, the rotation direction can be inverted again to perform a third run and so on, performing the number of runs appropriate for the type of fabric being treated in the machine.
[0008] The bath is then emptied from the tank and the roll is unwound, normally re-winding it on the trolley used for the loading operation.
[0010] Firstly, the linear speed of the fabric into the bath must be as constant as possible, in order to obtain uniform intensity of treatment.
[0011] The tension of the fabric must also be kept constant in order not to damage or even tear the fabric and to permit passage of the fabric along the path defined by the rollers and rockers.
[0012] It is also important to control the inertia, associated with the diameter of the rolls, during starting, stopping and variation of the linear speed of the fabric.
[0013] The reels of a Jigger type fabric treatment machine are driven by electric or hydraulic motors, mounted on and coupled to their shafts, and their speed is calculated via rotation transducers or encoders.
[0014] In particular, in the case of hydraulic motors, open hydraulic circuits are provided comprising fixed delivery pumps.
[0015] The aim of the present invention is to produce a hydraulic control circuit, for a Jigger type fabric treatment machine, that permits energy saving with respect to the current solutions.
[0016] A further aim of the present invention is to produce a hydraulic circuit, for a Jigger type fabric treatment machine, that permits easy control not only of the fabric speed and tension, but also of the inertia associated with the machine operating conditions.
[0017] A further aim of the present invention is to produce a particularly simple and functional hydraulic control circuit at limited cost.
[0018] These aims according to the present invention are achieved by producing a hydraulic control circuit, for a Jigger type fabric treatment machine, as illustrated in claim 1.
[0020] The characteristics and advantages of a hydraulic circuit for a Jigger type fabric treatment machine, according to the present invention, will become clearer from the following description, intended as a non-restrictive example, referring to the attached schematic drawings in which:
figure 1 is a side elevation section of a Jigger type fabric treatment machine;
figure 2 shows a diagram of a hydraulic control circuit of the machine of figure 1 produced according to the invention.
[0021] Figure 1 shows a Jigger type fabric treatment machine 10. Said machine 10 comprises, on the internal bottom of a closed chamber 11, a tank 12 designed to contain a treatment bath, positioned below an uncoiler reel 14 and a coiler reel 16.
[0022] A continuous strip of fabric 18, wound in a roll 20 loaded on the uncoiler reel 14, is guided, according to a direction 25, into the tank 12 along a path defined by rollers 22. Said fabric 18, after passing through the tank 12, is then wound onto the coiler reel 16 to form a roll 21.
[0023] Figure 2 shows how the two reels 16 and 14 are provided respectively with a hydraulic motor 26 and a hydraulic motor 24 that rotate in the same direction. These two motors 26 and 24 operate alternatively, driving or braking the fabric depending on whether the machine 10 is working in direction 25 or in the opposite direction 25'.
[0024] The two hydraulic motors 24 and 26 are controlled by a variable displacement pump 28, operated by a motor 44. The pump 28 can pump in two opposite directions to obtain alternatively the two machine 10 operating directions 25 and 25'; this is achieved by an electrical switching device, schematised in 45, applied to the pump 28 itself, and controlled by an electronic processor 50. When the pump 28 operates in direction 25, it has its delivery at 29 and intake at 30.
[0025] The connection between the pump 28 and hydraulic motors 24 and 26 respectively is provided, when the machine 10 is working in direction 25, by two branches 34 and 36 of a hydraulic circuit, intercepted by opening three valves 51, 52 and 53 and by closing three valves 51', 52' and 53'. In this phase, the branch 34 connects the motor 24, via points 39 and 37, to a brake valve 40, provided with a vent 42.
[0026] To obtain operation of the machine 10 according to the direction 25', the pump 28 is connected to motors 26 and 24 respectively via two branches 34' and 36' of a hydraulic circuit, intercepted by opening the three valves 51', 52' and 53' and closing the three valves 51, 52 and 53. In this phase, the branch 34' connects the motor 26, via points 39' and 37, to the brake valve 40.
[0027] In detail, the branch 36 consists of a closed circuit: it starts from delivery of the pump 28 at 29 and reaches point 39' via opening of the two valves 51 and 52. When the valve 53' is closed, the branch 36 leads to the motor 26. The branch 36 returns to the output of the motor 26 via closing of the valve 51', thus excluding a section of branch 36' between the valves 51' and 52' from intake of the pump 28 at 30.
[0028] Branch 34 starts from delivery of the pump 28 at 29. After reaching the motor 24, the branch 34 leads to its output via point 39. When valve 52' is closed and valve 53 is opened, branch 34 leads to point 37. When valve 53' is closed, branch 34 leads to the brake valve 40.
[0029] Branch 36' is symmetrical to branch 36. This branch 36' is also in a closed circuit: it starts from delivery of the pump 28 at 30 and reaches point 39 via opening of the two valves 51' and 52'. When valve 53 is closed, branch 36' leads to the motor 24. The branch 36' returns to the output of the motor 24 via closing of the valve 51, thus excluding a section of branch 36 between the valves 51 and 52 from intake of the pump 28 at 29.
[0030] Branch 34' starts from delivery of the pump 28 at 30. After reaching the motor 26, the branch 34' leads to its output via point 39'. When valve 52 is closed and valve 53' is opened, branch 34' leads to point 37. When valve 53 is closed, branch 34' leads to the brake valve 40.
[0031] The electronic processor 50 controls the pumping direction of the pump 28, identified by the switching device 45, and consequent opening or closing of the valves 51, 52, 53, 51', 52' and 53'. The processor 50 also controls the parameters of the pump 28 and brake valve 40.
[0032] In particular a first operating phase will now be described in which the fabric 18 is treated according to direction 25; for the opposite direction, the same considerations apply in reverse since branches 36 and 34, as seen, are symmetrical to branches 36' and 34'. In practice, branches 36' and 34' are a duplicate of branches 36 and 34, and are designed to permit operation of the machine 10 in the two directions 25 and 25'.
[0033] In this phase, the hydraulic motor 26 connected to the reel 16 drives the fabric 18 while the hydraulic motor 24, connected to the reel 14, brakes the fabric 18.
[0034] The constant linear speed of the fabric 18 is obtained by continuously comparing readings of impulses generated by the rotation of two rotation encoder transducers (not shown) mounted on and coupled to the hydraulic motors 24 and 26.
[0035] The following relation derives from the linear speed conditions of the fabric 18 which is the same at the outlet of roll 20 from the uncoiler reel 14 and at the inlet of roll 21 onto the coiler reel 16:
where ω1 and ω2 are the numbers of impulses of the encoders of motors 24 and 26 respectively, and where d1 and d2 are the instantaneous external diameters of the rolls of fabric 18 wound on the uncoiler reel 14 and coiler reel 16.
[0036] Via this relation, since d1 and d2 are known, the electronic processor 50 of the machine 10 is able to send correction signals to the pump 28 and to the valve 40 in order to obtain a constant linear speed.
[0038] The relation according to which the working torque is obtained by a pressure that acts on the displacement of the hydraulic motor is known. The motors 24 and 26, since they are both connected to the delivery of the pump 28 at 29, are powered by the same working pressure. In the phase in which the fabric 18 runs from reel 14 to reel 16, the diameter of the roll 21 wound on the reel 16, and therefore the lever arm, is less than the diameter of the roll 20 wound on the reel 14. In this way, the motor 26 delivers a drive torque sufficient to move the motor 24 across the fabric 18. In addition to this, the working pressure helps rotation of the motor 24 which therefore tends to rotate without generating tension on the fabric 18.
[0039] For this reason the brake valve 40 is used which generates a back pressure opposing the working pressure and therefore creates, as a final effect, a tension that can be calibrated on the fabric 18. This tension is linked to the pressure difference value between the working pressure and the back pressure generated by the valve 40.
[0040] As the fabric 18 is gradually wound on the reel 16, diameter variations are generated between rolls 20 and 21. When the diameter of the roll 21 increases, the operating pressure on the motor 26 must also increase proportionally, but the increase in the operating pressure also generates a greater rotation torque on the motor 24. Furthermore, since the diameter of the roll 20 has been reduced in the meantime, the motor 24 requires less torque. The relation between operating pressure and braking torque, given by the back pressure of the valve 40, must therefore be constant.
[0041] The reels 14 and 16 are subject to considerable load variations, depending on the diameter of the rolls 20 and 21; the inertia generated during the start, stop and speed correction phases must therefore be controlled.
[0042] As can be seen from the diagram of figure 2, the flow sent to 29 by delivery of pump 28 returns, via branch 36, to 30, i.e. to the pump 28 intake, thus generating a braking effect. Furthermore, if pressure peaks caused by excess inertia are created during movement, pump 28 is able to discharge said peaks via its own internal safety valve.
[0043] Counting of the length of the fabric 18 to be treated, which must be accurate enough to perform the inversions without the fabric sliding out of the reels 14 and 16, is also necessary. This count is controlled by the electronic processor of the machine 10 via the encoders mounted on and coupled to the hydraulic motors 24 and 26, the same as those that permit control of the linear speed.
[0044] During loading of the roll 20 onto the reel 14, the encoder connected to the motor 24 records the total number of impulses transmitted in the form of an incremental value. At the end of loading, after the beginning of the fabric 18 has been conveyed to the coiler reel 16 and it begins to wind the fabric 18, the count re-starts in decreasing mode until a minimum value is reached. This value corresponds to the stop reference value before the subsequent inversion.
[0045] All the functions governing the machine 10 are controlled by the electronic processor 50 which dialogues with peripheral cards, actuating the machine functions described above.
[0046] In the description, provided as a non-restrictive example, electrical control two-way valves are indicated whereas to simplify the system, three-way electrical valves and hydraulically operated valves controlled by the circuit pressure are used.
[0047] The hydraulic control circuit, for a Jigger type fabric treatment machine, subject of the present invention, has the advantage of permitting considerable energy saving. In fact, the variable displacement pump, controlled by the electronic processor governing the machine, delivers only the flow rate and pressure necessary for operation of the machine, following the work parameters set by the operator.
[0048] A further advantage of the hydraulic control circuit, subject of the present invention, is that it permits balancing of the machine inertia almost automatically, exploiting the principle of the closed circuit pump.
[0049] The hydraulic control circuit for a Jigger type fabric treatment machine, conceived as above, is subject to modifications and variations, all falling within the scope of the invention; furthermore all the details can be replaced by technically equivalent elements. In practice, any materials and dimensions can be used according to technical requirements.
1. Hydraulic control circuit for a Jigger type fabric treatment machine (10) where a
roll (20) of fabric (18) is unwound by an uncoiler reel (14 or 16) and where the fabric
itself (18) is guided into a tank (12) containing a treatment bath, before being rewound
on a coiler reel (16 or 14) to form a roll (21) of treated fabric (18) and vice versa,
the reels (14, 16) being operated by hydraulic motors (24, 26) connected via branches
(34, 36; 34', 36') of the hydraulic circuit to a pump (28), characterised in that said hydraulic circuit is of the closed type, a brake valve (40) being provided which
exerts a variable back pressure on the motor during braking (24 or 26).
2. Hydraulic control circuit according to claim 1, characterised in that each of the two branches (34, 36; 34', 36') features a closed circuit section (36,
36') which starts (at 29 or 30) from a delivery of the pump (28), powers at least
one motor (26 or 24) and returns (at 30 or 29) to an intake of the pump (28), where
the pressure of said pump (28) is modified as the diameter of the roll (21 or 20)
wound on the coiler reel (16 or 14) increases.
3. Hydraulic control circuit according to claim 1, characterised in that in each of the two branches (34, 36; 34', 36') a further branch (34 or 34') is provided
comprising a closed section that starts (at 29 or 30) from the delivery of the pump
(28), powers at least one motor (24 or 26) and connects it to said brake valve (40)
which exerts a variable back pressure on it, switching said motor (24 or 26) to braking
mode with braking torque regulated by said back pressure.
4. Hydraulic control circuit according to claim 1, characterised in that said pump (28) is a variable displacement pump.
5. Hydraulic control circuit according to claim 1, characterised in that said pump (28) is provided with a safety valve to discharge pressure peaks.
6. Hydraulic control circuit according to claim 1, characterised in that said motors (24, 26) are provided with rotation transducers, where said transducers
supply information to an electronic processor of the machine (10) which controls the
parameters of the pump (28) to obtain the speed of the fabric (18) prescribed by an
operator and/or to obtain the tension of the fabric (18) prescribed by an operator,
where this is achieved by maintaining constant the relation between pressure of the
pump (28) and braking torque on the motor (24 or 26), generated by the back pressure
of the valve (40).
7. Hydraulic control circuit according to claim 1, characterised in that said machine (10) features reversible operation, providing valves (51, 52, 53, 51',
52', 53') in said branches (36, 34; 34', 36').