SHOE PRODUCTION MACHINE AND METHOD OF OPERATION

Description

Description of the industrial invention in the name of AVANTIUM SRL with registered office in Corso Novara 218, 27029 Vigevano (PV) with the title "Processing machine of a shoe and method of operation" ****** The present invention relates to a shoe manufacturing machine. The present invention also relates to a method of operation thereof. In the shoe manufacturing industry there are well-known processing machines that They include a hydraulic circuit which in turn includes hydraulic actuators which move the various parts of the mechanism of the machine that executes the volute processing. For example, there are known assembly machines that perform the various assembly operations on footwear. For example, machines are known generically referred to as “pre-assembly-assembly” which perform the fixing of at least a first part of the upper to the insole. In shoe making machines, an operator inserts into the machine a shape with the part of the shoe to be worked, for example with the upper to be assembled, he positions it and starts the machine. The machine performs the expected operations, by actuating its actuators following preset cycles and at the end the operator removes the last with the worked shoe and inserts a new last with the new one part of the shoe to be processed and then start a new machine cycle. For example, the machine may include a variable number of grippers arranged in semicircle to grasp the edge flap of an upper placed on a suitable shape and pull it downwards to tighten and center the upper on the shape. Subsequently, the pulled flap is folded and glued to the insole, always from the same machine, so as to block the upper in the desired shape. relative position of the clamps with respect to the last on which the upper and the the force with which they pull the material therefore determines the centering and correctness or not of the assembly. The positions of the calipers and their tensile force depend naturally from the particular operation from the specific upper and can also vary during the operation of the machine. The sequence of operations performed by a machining machine footwear, however, necessarily involves rest times, movement times and static force application times of the actuators themselves. Furthermore, in some cases, there they are also intermediate operations in which the operator's intervention is required to operate particular mechanisms of the machine or make adjustments. The pressure requirement in the hydraulic circuit is therefore highly variable in time. Typically a shoe making machine therefore includes a pump hydraulics that feed a circuit fluid accumulator from which the actuators draw the fluid under pressure for their operation. The pressure in the accumulator is kept approximately constant at a maximum value thanks to to a simple maximum pressure valve. There are machines that when the working pressure is reached in the accumulator They automatically drain the oil while the pump continues to run. In some cases, the pump motor shuts off when the machine is in a state of non-operational waiting and as soon as the user starts a machine operation (for example (for example, pressing a pedal or a control lever) the pump restarts. Such cycles The pump can also be switched on and off very quickly intervals, with continuous starts and stops of the electric motor that controls the pump. In addition to a rather annoying background noise, such well-known ways of functioning of the known machines involve high energy consumption of the machine and a wear of its hydraulic circuit. Furthermore, the oil continues to flow uselessly in the hydraulic circuit and heats up unnecessarily. The general purpose of the present invention is to provide a machine for processing energy-saving footwear. Further purposes are to reduce noise machine operation and wear of the hydraulic circuit. In view of these purposes, it was thought to create, according to the invention, a method of pressurized fluid supply to the hydraulic actuators of a machine processing of a shoe, using a hydraulic pump controlled by a electric motor and a pressurized fluid accumulator, characterized by the fact that use an engine control unit that measures, by means of a sensor pressure, the pressure coming out of the accumulator and controls the rotation speed of the electric motor as a function of the pressure detected by the sensor. Always according to the principles of the invention, it was also thought to create a shoe-making machine comprising a group of processing and mechanisms operated by hydraulic actuators, characterized by the fact that comprising a power supply unit for supplying a fluid under pressure for hydraulic actuators comprising a hydraulic pump driven by a motor electric, a motor control unit, a pressurized fluid accumulator and a pressure detection sensor at the outlet of the power unit, the power unit motor control by controlling the rotation speed of the electric motor in function of the pressure detected by the sensor. To clarify the explanation of the innovative principles of this The invention and its advantages over the known art will be described below, with with the help of the attached drawings, an exemplary implementation applying these principles. In the drawings: -figure 1 represents a schematic view of a processing machine footwear made according to the invention; -figure 2 represents a graph of a possible trend of the pressure of the machine hydraulic circuit; -Figure 3 represents a block diagram of the control and power supply system of the machine's hydraulic circuit; -figure 4 represents a flow diagram of the system operation control and power supply of the machine's hydraulic circuit. With reference to the figures, figure 1 shows a schematic machine footwear manufacturing carried out according to the invention and generically indicated with 10. As will be clear later, the machine 10 comprises a group of machining 15 and mechanisms operated by hydraulic actuators 17 for operation machine operation for the operations to be performed. The workmanship can be of any type known for footwear and machine It will therefore be able to include a known operational part 11 with mechanical systems and hydraulic actuators for performing desired machining operations of a footwear or part of it and which are easily imaginable by the expert technician. For example, the working part of the machine may be of the type known for the positioning and ironing of an upper on a last for gluing to the insole. The operating mechanisms of such a machine can be easily imagined by the expert technician and will therefore not be shown or described here in detail. The general operational structure of the machine and the processing cycle that it performs are essentially known in themselves and will therefore not be described or shown in detail, being easily imaginable by the expert technician on the basis of this description. In particular, the machine 10 can be adapted and perform the assembly of the upper of a shoe on an insole. For example, it can be of the type of machine called “pre-assembly-assembly”. The machine 10 may comprise a loading and processing area 12 in which the operator positions a last 13 with the shoe or part of the shoe to be worked (for example the upper to be assembled). The loading area includes for this purpose a suitable support 14 on which the shape 13 is mounted. The machine may comprise a known machining group 15, for example of gripping and pulling and, if necessary, fixing the upper. The working group 15 will have mechanisms 16, such as upper gripping and traction clamps, operated by suitable hydraulic actuators, generally shown in dashed lines and indicated with 17. There may also be known systems 18 (e.g. optical) to help the operator in positioning the shoe or part of it to be assembled. Usually the machine includes among the 17 actuators also actuators of relative movement between support 14 and working group 15 to move the shoe being processed from an insertion and extraction position from the machine (shown in solid line in figure 1) to a working position within the machining group 15 (shown in dashed lines in figure 1). In the case of a 15-piece workgroup with gripping and traction clamps, these clamps will be able to be a plurality of gripping clamps advantageously arranged in an arc on opposite sides of the reception area of ​​the shoe to be worked on, so as to grasp and pull a flap of the edge of the upper to fold it over and fix it on the insole. Usually such a plurality of clamps can be arranged around the tip area of ​​the footwear to grasp the edge of the upper that goes from the tip to the beginning of the hollow of the footwear. The clamps can be connected to adjustment means so known for allowing the operator to adjust their action on the upper. The processing group 15 may also include known glue dispensers, not shown, (e.g. heated nozzles for thermoplastic glue dispensing) usually placed between the clamps and the support 12 for the dispensing of glue in order to glue the stretched upper to the insole. Typically, there may also be additional known operational bodies of the machine such as locking devices (not shown and including for example upper pressure pads) and which for example can press the upper against the last to prevent the upper from shrinking or moving during the time between the release of the upper itself by the pliers and the closing of appropriate plates ironing. Known pressure devices (also not shown) can be provided for the pressing the turned edge onto the glue with sufficient pressure. All the mechanisms mentioned can be operated by hydraulic actuators 17 behind control of a control unit 19 known in itself, which will comprise both a control system hydraulic circuits 20 for actuator activation and an electrical circuitry system or electronic 21 (for example with a suitably programmed microprocessor) for command the machine to perform all the movements of the mechanisms of the machine with the times and methods required for the specific job. A control panel control 22 may also be present to allow the operator to send machine controls. Panel 22 may also include known displays (indicator lights, displays, etc.) to signal the operating status of the machine to the operator machine itself. Up to this point, a well-known shoe-making machine has been described. The machine 10 comprises a feed unit 23 for feeding a pressurized fluid for hydraulic actuators. In particular, the hydraulic part 20 of the control unit 19 can receive from the unit of supply 23, for example through a delivery duct 24 the fluid in pressure for the hydraulic circuit controlling the machine's actuators 17. A return line 25 returns the fluid from the hydraulic part 20 to the unit power supply 23. According to the principles of the invention, the power supply unit 23 comprises a hydraulic pump 26 controlled by an electric motor 27 in turn controlled by a motor control unit 28. The pump 26 may advantageously be a gear pump. The electric motor 27 can advantageously be a motor three-phase electric motor. The motor control unit 28 may comprise a known per se electronic circuit, advantageously microprocessor-based (for example a PLC) appropriately programmed. The engine control unit 28 receives signals depending on the pressure present in the delivery duct 24, detected by a pressure sensor 29. Depending on the pressure detection of the pressure sensor 29, the engine control unit 28 controls the speed of the motor 27 and consequently the pump 26, as will be further described below. In the case of a single or three-phase electric motor 27, the motor control unit 28 may include an inverter (or other suitable electronic drive) to provide the motor 27 the suitable power supply to control the rotation speed of the engine, as the technician can easily imagine. Using the inverter involves the advantage of being able to power the motor with different frequencies (for example up to 100Hz with motors with a nominal frequency of 50Hz. This possibility allows in easy way to significantly increase the maximum engine rpm and consequently, it reduces the time required to reach working pressure. Pump 26 supplies pressurized fluid to an accumulator 30 connected to the outlet of the pump 26 and to the delivery line 24 through a distributor circuit hydraulic 31, which may include safety and maximum pressure valves, distributor drawers, etc. The distributor circuit 31 advantageously has a maximum or over-maximum pressure regulation equipped with “non-return”. The use of an overpressure safety valve allows for example in in case of failure (pump failure) to avoid reaching pressures excessive (for example higher than 65 bar) also allows in case of avian flu power supply system 23 to force the hydraulic circuit to operate with “continuous” operation (for example with a pressure of 65 bar) so that the part 11 machine operating mode can continue to operate under the control of its unit of command 19. Preferably, pump 26 receives hydraulic fluid (in particular diathermic oil) from a source 32 and the hydraulic system is drained through a drain 33 (which allows the recirculation of the fluid from the inlet 32 ​​according to a system known). The engine control unit 28 preferably includes a memory 34 in the which at least one maximum pressure value Pmax and one value of minimum or recharge pressure Pmin. The pressure Pmax is generally the recharge pressure maximum work required by the machine. The pressure Pmin is generally the pressure minimum still acceptable to still have the machine working correctly. Such Pressure values ​​can also be dynamically varied depending on the phases of work addressed by the machine, as will be clear from what follows. Advantageously, during operation of the machine 10, the control unit engine 28 reads the pressure value supplied by sensor 29 at the input, establishes whether the pressure detected by the sensor is close to or below the minimum pressure or recharge Pmin and if this is established, then the engine control unit 28 starts the pump 26 controlling the motor 27 in speed according to a pre-established law up to to approach or reach the maximum pressure Pmax, always detected by the sensor 29. Once the Pmax value is reached, the engine control unit 28 stops the engine 27 and the part hydraulics 20 which controls the hydraulic actuators of the machine is powered solely from the pressurized fluid contained in the accumulator 30. As will become clear later, the engine control unit 28 between a value of minimum pressure and a maximum pressure value preferably controls the engine to follow a predetermined speed profile and slow down the engine at least as the maximum pressure approaches. The activations of the various hydraulic drives 17 for normal operations processing performed by the machine will gradually reduce the pressure of power supply coming from the power supply unit 23. When the power supply unit engine control 28 detects through sensor 29 that the supply pressure on output 24 has dropped below the minimum or recharge pressure Pmin, then the unit of motor control 28 activates motor 27 again, controlling its speed according to the pre-established law to recharge the accumulator 30 and reach again the Pmax value at the power output 24. The velocity profile, i.e. the pre-established law of variation of the velocity V of the pump between the pressure value Pmin and the pressure value Pmax, can be varied to gradually reach the Pmax value. For example, as will be clarified below, the speed profile may include between the minimum pressure value and the maximum pressure value at least one step further close to the maximum pressure in which the speed is a function or proportional to the difference between maximum pressure and minimum pressure, or also in which the speed is function or proportional to the difference between maximum pressure and detected pressure from the sensor. For example, the pre-established law of variation of the speed V of the pump in the the transition from the pressure Pmin to the pressure Pmax could be V=f(Pmax-Psens), that is, a function of the difference between the pressure Pmax to be reached and the actual pressure Psens continuously detected by sensor 29 until it is reached of the pressure Pmax. This will ensure that the pressure in the circuit approaches the Pmax pressure. gradually, with the pump slowing down until it stops when the pressure Pmax. During the various operating cycles of the machine, the pressure trend of the fluid in the accumulator 30 and which is sent through the outlet 24 to the actuators It will therefore be similar to what is shown as an example in the graph in figure 2. In essence, when engine control unit 28 is activated (e.g. when the machine is turned on, it starts reading the pressure sensor 29 of the hydraulic circuit, determines the deviation between the set Pmax pressure (which is essentially the pressure considered standard for the operation of the machine) and the actual circuit pressure, decides whether it is under the charging pressure Pmin and in this case it controls the motor (for example via an inverter or other system known required by the type of electric motor used) with variable speeds depending on of the pressure difference between Pmax and the pressure read (minimum revolutions, gains of the ring, etc.), so as to gradually reach the pressure Pmax. When the hydraulic circuit has reached the desired working pressure Pmax the engine stops completely. From that moment on, even if some hydraulic actuators of the machine is activated to make some movement, the engine does not start turn until you reach a “recharge” point, that is, the pressure Pmin. As soon as the pressure drops below the Pmin pressure the engine restarts with the number of variable speed as described above to reach the working pressure Pmax and then it turns off again. By using a suitably fast motor (and therefore a pump), the system allows for rapid recovery of Pmax pressure even in the event of sudden drops of pressure towards the Pmin level. For example with an electric motor controlled by an inverter that allows the motor to be powered at a high frequency, when there is are sudden drops in pressure the fact that the engine can run at a higher frequency high (for example up to 100Hz instead of 50Hz) allows you to recover the pressure more quickly. As an example, a three-phase motor powered at 50 Hz can be used It rotates at 1400 / 1500 rpm, while when powered at 60 Hz the engine rotates at 1700 / 1800 rpm However, it is possible to use motors with higher rpm, for example an engine that can go from 0 to 3000 rpm. Pump 26 can also have an operating range in which it must be preferably contained the variation in engine speed. For example, the pump It can have an operating range from 200 rpm to 4000 rpm. The law of variation of speed as a function of pressure in the circuit can be a simple proportional law. The coefficient of proportionality can depend on the specific application of the machine, as now easily imaginable by the technician. It is also possible to create a speed profile that includes between the value of minimum pressure and the maximum pressure value a section closer to the minimum pressure at which the velocity is constant at a fixed value (for example of maximum speed). After reaching a preset pressure value measured by the sensor, the speed profile can then decrease in speed according to a preset function towards the maximum pressure Pmax. In particular, one can have a velocity profile that initially has a step of operating at maximum speed and then decreasing (for example in a proportional) after the difference (Pmax-Psens) has dropped below a value pre-set, so as to optimize the charging speed but also to still get close in a “gentle” way to Pmax and avoid, for example, overpressures. For example, as long as the difference (Pmax-Psens) is above a certain value X the engine speed is Vmax, then becomes proportional straight line with slope equal to the difference between Pmax and Pmin when the difference (Pmax-Psens) is below the X value. For example, you could set Pmax (working pressure) = 55bar, Pmin=40bar and X=10 bar as the delta above which the velocity is 100%. The system of the invention below 40 bar could therefore activate the engine to recharge the accumulator with the engine speed equal to 100%. The 100% speed will be used up to 45 bar (i.e. 55-10), after which it can be directly proportional to the pressure difference between 45 bar and 55 bar, until reaching Pmax. So as the pressure approaches 55 bar the engine will slow down. As the valves are operated, the pressure drops. As soon as the pressure drops below the charging pressure, the system starts and the engine rotate until the working pressure is reached (also called operating pressure) exercise) via a variable rotation command proportional to the difference between working pressure and circuit pressure. The accumulator will be able to supply oil in pressure even when the engine is off for a sufficiently long time avoiding continuous or very frequently occurring operations of known systems. A data connection 35 may also be provided between the control unit 19 which controls the machine operations and the engine control unit 28 to exchange data and information between the two units. In particular, the control unit 19 can be connected to the command unit motor 28 to control changes in the rotation speed setting of the electric motor 27 as a function of the pressure detected by the sensor 29. For example, the engine control unit 28 can receive signals from the control unit 19. commands to modify the values ​​of Pmax and / or Pmin or even the variation law of the engine speed depending on the specific operating needs of the machine, such as particular processing phases that require more or less pressure in the hydraulic circuit. If necessary, the engine control unit 28 can also observe some specifications engine operating conditions 27. For example, it may include a parameter that determines the minimum engine speed when activated. With this parameter the engine rpm will not drop below the predetermined rpm when the pressure detected by the sensor will approach the Pmax pressure, but will continue to turn at this minimum speed until the pressure Pmax is reached and then will turn off. This can be useful for example when the engine has a cooling system with self-ventilation effective only up to a preset engine speed. in particular, this may be the case when a classic three-phase motor is used, which therefore also needs a minimum number of revolutions to be able to exploit its “self-ventilation” and cool down automatically. Furthermore, the 26 pump can also have a minimum number of revolutions to ensure the thrust of the oil, although it is usually lower than the number of revolutions for the auto- engine ventilation. Figure 3 shows an example of a possible block diagram of the system. according to the invention. The power supply unit 23 performs the process control (block 40) by means of the engine control unit 28 which receives from the sensor 29 (block 41) the pressure value in the hydraulic supply circuit. The control of process controls the motor (for example via an inverter, block 42) by emitting the appropriate commands. A measuring block can also be provided of the energy consumed (block 43), information emission blocks (ad example an information display - block 44) and a log file creation system (block 45). The process control block 40 may also preferably exchange data with the machine control unit 19 (I / O blocks 46 and 47 data). Figure 4 shows a flowchart of a possible operation. operating system according to the invention. For example, the operation represented in this diagram can be realized as a software program of the engine control unit 28. The various blocks of the diagram are self-explanatory of the various operational steps. At this point it is clear how the intended goals were achieved. The system according to the invention allows to save energy significantly, avoids to turn oil unnecessarily and reduces the heating of the oil itself because the oil it is no longer continuously discharged. In the operating cycle of the shoe manufacturing machine there are for example moments of pause, moments when the oil in the accumulator is sufficient to move some parts of the machine through the corresponding hydraulic actuators, moments where the actuators remain stationary under pressure (for example when the shoe is pressed) and no further oil is required. Even during a processing cycle There may be times when the operator stops the machine to operate manually on the shoe in it. Furthermore, between one processing cycle and the there may be a variable time during which the machine is stationary with the operator who changes the shoe to be worked on or manually takes care of some details of footwear. These are all times when the pump motor can shut down and remain worn out. It has been seen that with the system according to the invention it is possible to obtain savings in the order of 10% or even more compared to a machine without the unit power supply operating according to the invention. Furthermore, the fact that the engine stops completely for periods of time, even quite long long significantly reduces background noise compared to known machines. The use of a motor that can quickly vary the number of revolutions per minute in a wide range allows to further reduce consumption and increases further the dynamic response of the system. Of course, the above description is of an embodiment applying the principles innovative principles of the present invention are reported as an example of such principles innovative and therefore should not be taken as a limitation of the scope of the patent here claimed. For example, the shoe manufacturing machine may be of type different from the one described and provide other or different devices for the assembly of footwear, also by virtue of the type of footwear and the system of chosen fixing (glue, thermoplastic, nailing, etc.). The system described here may also include further elements, either as part machine operation as well as part of the power supply unit control. for example, a flow transducer combined with the transducer can be used pressure, so as to also have an indication of how much oil the machine is requiring machine. The power supply unit according to the invention can be integrated as part of the processing machine or even be foreseen as an additional unit to a machine of known technique to replace its normal fluid supply in pressure. The Mandatory Eng. Marco Lampis Della Dragotti & Associates Srl (Registration 564)

Claims

CLAIMS 1. Method of supplying pressurized fluid to the hydraulic actuators (17) of a shoemaking machine (10), using a hydraulic pump (26) controlled by an electric motor (27) and a pressurized fluid accumulator (30), characterized by the use of a motor control unit (28) which measures, by means of a pressure sensor (29), the pressure output from the accumulator (30) and controls the rotation speed of the electric motor (27) as a function of the pressure detected by the sensor (29).

2. Method according to claim 1, characterised by defining a maximum pressure value and a minimum pressure value and the motor control unit (28) is set to activate the electric motor (27) when the pressure value detected by the sensor (29) drops to or below the minimum pressure value and to switch off the electric motor (27) when the pressure value detected by the sensor (29) reaches the maximum pressure value.

3. Method according to claim 2, characterised in that the motor control unit (28) is set to control the motor, between the minimum pressure value and the maximum pressure value, so as to follow a pre-established speed profile and slow down the motor at least when approaching the maximum pressure.

4. Method according to claim 3, characterized in that the velocity profile includes between the minimum pressure value and the maximum pressure value at least a section close to the maximum pressure in which the velocity is a function or proportional to the difference between maximum pressure and minimum pressure.

5. Method according to claim 3, characterized in that the speed profile Ref.: 24ST28I includes between the minimum pressure value and the maximum pressure value at least a section close to the maximum pressure in which the speed is a function or proportional to the difference between maximum pressure and the pressure detected by the sensor.

6. Method according to claim 3, characterised in that the velocity profile includes between the minimum pressure value and the maximum pressure value a section close to the minimum pressure in which the velocity is constant at a predetermined value, preferably a maximum velocity value.

7. Method according to claim 6, characterized in that after reaching a predetermined value of pressure measured by the sensor, the velocity profile decreases from the predetermined value according to a predetermined function.

8. A shoe making machine comprising a working unit (15) and mechanisms operated by hydraulic actuators (17), characterised in that it comprises a power supply unit (23) for supplying a pressurised fluid to the hydraulic actuators (17) comprising a hydraulic pump (26) operated by an electric motor (27), a motor control unit (28), a pressurised fluid accumulator (30) and a sensor (29) for detecting the pressure output from the power supply unit, the motor control unit (28) controlling the rotation speed of the electric motor (27) as a function of the pressure detected by the sensor (29).

9. Machine according to claim 8, characterised in that the motor control unit (28) comprises a memory (34) containing a maximum pressure value and a minimum pressure value and the motor control unit (28) activates the electric motor (27) when the pressure value detected by the sensor (29) drops to or below the minimum pressure value and switches off the Ref.: 24ST28I electric motor (27) when the pressure value detected by the sensor (29) reaches the maximum pressure value.

10. Machine according to claim 9, characterised in that the motor control unit (28) controls the motor to follow a pre-established speed profile between the minimum pressure value and the maximum pressure value and slows down the motor at least when approaching the maximum pressure.

11. Machine according to any of the preceding claims 8 to 10, characterised in that it comprises a control unit (19) connected to control the hydraulic actuators (17) and connected to the supply unit (23) to receive from the latter the hydraulic fluid for controlling the hydraulic actuators (17).

12. Machine according to claim 11, characterised in that the control unit (19) is connected to the motor control unit (28) to control variations in the rotation speed setting of the electric motor (27) as a function of the pressure detected by the sensor (29).

13. Machine according to any of the preceding claims 8 to 12, characterised in that the mechanisms operated by hydraulic actuators (17) comprise mechanisms with grippers (16) for gripping and pulling the edges of an upper.