FR2709993A1 - Advanced device for welding control. - Google Patents

Abstract

The invention relates to an improved device which makes it possible to control the automatic method of resistance spot welding, comprising an analog data input block (INAL), a block (IODIG) for communication with the outside and memories (ROM) and (RAM), connected via a bus (7) to a processor unit (CPU) in communication with an external terminal for the command and control of a welding machine (MS) and of its relative initiator (IS). A connector means (12) of an external memory (ME) is provided with said bus (7) and the processor block (CPU), while a clock block (BOR) provides directly to said processor block (CPU) time references. real absolute and a control unit of the network supply (PF) ensures the operation of an emergency battery (BT) for the continuity of supply of the unit (BOR) and the memory (RAM) and puts in action the processor unit (CPU) to keep the device operational.

Description

DESCRIPTION

  The present invention relates to an improved device for controlling the weld, that is to say a device which makes it possible to control the automatic process of spot resistance welding. The automatic welding processes of industrial lines, for example the welding of hulls or other metal parts of cars, are carried out by welding machines each of which being controlled by control devices which form the object of the present invention and whose general roles are: - adjusting the welding current; - the timing of the welding process; - processing and timing of accessory operations (eg opening and closing of clamps, synchronization with external devices, control of cooling water and air pressure for controlling pneumatic valves, etc. .); the user interface; - the interface to a network for remote processing of several welding control devices. The welding control devices currently on the market include one or two processor blocks which process the generation of pulses for the initiator of the welding machine, the diagnosis, the input / output (input / output), the serial / parallel doors, the interface with the processing network, etc. In addition, the processor or the processor block, calculates the effective current for each of the welding cycles, determines the angle of initiation for the cycle next and has the

  role of driving the digital converter

  analog for the actuation of a possible proportional electric valve. All these complex functions are nowadays executed by known welding control devices by means of internal programs implemented in firmware (specific programs) (firmware) on EPROM, for the operational internal and cyclic functions, and via a user program set up on the RAM memory for all the functions, parameters and characteristics relating to the particular operational cycle that must be developed. These user programs, which are variable and diversified on a case-by-case basis according to production requirements and typologies, can be set up and modified via the connection which can be removed from a small portable terminal, conventionally called, to

  facilitate the description, "small keyboard", or else

  usually via the logic control and processing network of several welding control devices. Indeed, a welding line normally never provides a single welding machine and its single relative control device, but on the contrary several machines and their corresponding control devices, intended for the same or for various welding operations, all being controlled to a processing network controlled by a remote processing unit whose role is to process and modify one or more user programs in real time, the timing of operational cycles, the continuous diagnosis of each of the control devices and of the network, as well as the storage of cycle data

executed (= history, history).

  The individual control device of known type, if it is not connected in the network, is not able to process a program timer different from that of the user program set up in the RAM through said small keyboard, cannot execute any modifications or specific programs, except through specific manual reprogramming, or modification of programs residing in RAM, and it is also unable to perform a timer comparison, since 'the reference to

  absolute time which is only provided by the network.

  In addition, the individual control device of known type is able to carry out an instant diagnosis in the form of an alarm signal, which requires the direct intervention of the operator, which cannot be corrected automatically, but not a diagnosis. cycle and even less an operational history with progressive time reference exceeding the individual operational cycle (sometimes at the level of individual weld operated). Known control devices, if they are not connected in the network, in the event of a power failure, are not even able to maintain the operational condition since it lacks the buffer supply; this is why, once the network supply has been restored, the device and the relative welding machine must be replaced before going on to a new operational cycle. In such an eventuality a RAM memory with autonomous supply is indeed able to keep the programs, but not

  the data of the current welding cycle.

  All these limits, as in fact in industrial reality there is no installation of a single control device, have been overcome by the processing networks which, via a processing unit distant (even, in the case of simple solutions, a conventional personal computer) which provides for the processing of the most necessary user programs, their timing and their comparison with absolute time, the

diagnosis, history, etc ...

  By the term "diagnostic" is meant a set of information, collected for each weld, which the control device can visualize in codified form on a display (table) of the small keyboard, if it is connected, or memorize and visualize on the distant development unit of the network. For example, certain diagnostic information is: - the result of the weld, positive or negative, with error code; - the effective current measured by the control device; - the duration of the weld;

  - the name of the user program used; etc ...

  By the term "history", or even "alarm history", is meant the memorization of a number, for example fifty, of alarms which have been verified, the programs which produced them and the absolute time during which they are verified, in the "history" can also be included the data of the welds which worked well. In turn, systems in the network have their own limitations and drawbacks. The installation along an industrial line of several welding control devices in the network with a distant processing unit presents obvious technical complexities and costs which are not negligible which make them unsuitable for small production realities that need, for example, only two or three welding machines and their relative control devices. We can indeed consider broadly that for the networks made up of few operational units the cost of the welding control devices alone only influences about 20% - 30% on the cost of

  the complete relative installation in the network.

  There are also industrial realities which include similar welding lines, which can be processed with the same user programs under a single network, which are in fact arranged at great distances from one another, even a few hundred meters, and therefore cannot be slaved to the same network or else must provide for the adoption of very expensive network repeaters; we are thus forced to multiply the networks. Any disturbances to the remote processing unit or to the network include the isolation of the slave control devices which, during the repair time, operate within the limits described above and must exceptionally be replaced and reprogrammed one by one and manually via said small keyboard, in any case remain deprived of diagnosis and operational history as well as

  of the absolute time reference.

  Finally, user programs are difficult, or rather they are not easily and not quickly transferable from one network to another, while individual programs or modifications implemented on the control device via the small keyboard cannot be multiplied or transferred from one device to another. We cannot currently use a bank of user programs to quickly insert and modify, one control device after another in the event of differentiation of operational cycles or production, but it is necessary to reprogram the production unit distant which must be operated by the expert technician and

  not tempted by the worker on the line.

  It goes without saying that all the limitations and drawbacks which have been described, even if they seem to be exceptional, in industrial reality represent enormous problems directly linked to the continuity and proper functioning of automatic lines, and relative quality control

from production.

  The object of the present invention is therefore to provide an improved weld control device capable of fulfilling all the described functions of the known devices controlled in a network, but which is also able to operate separately and which can therefore be connected in the network according to conventional installations, but which can be isolated by eliminating all the limits and all the drawbacks of known devices. The object of the invention is therefore to provide a control device with its autonomous counterpart of the absolute time and of the timing of the programs, an autonomous memory of the user programs which can be quickly set up, modify and multiply, a capacity diagnostic and operational history, as well as keeping the operational condition in case

power failure.

  These objects of the invention and still others are achieved by virtue of the improved welding control device in question, of the type which includes an analog data input block (INAL) of the uses controlled by the control device and the outside world. , a block (IODIG) of communication with means external to the control device, a memory (ROM) and a memory (RAM), connected via a bus to a processor block (CPU), which is at its tower in communication via an interface (IT) with a door for the connection with an external portable terminal of manual programming called small keyboard (T), of processing of the signals in output and enree for command and control , via opto-isolator circuits (OIS) and interfaces (COND), a welding machine (MS) and its relative initiator (IS), which, from a general point of view, characterized by the fact that it comprises a connector means for the a link that can be removed from an external memory (ME) with said bus and with said processor block (CPU), a clock block (BOR) which provides directly to said processor block (CPU) references to absolute real time, for the timing of operational processes, for diagnosis and for operational history, a network supply control block (PF), which is provided with sensors for supplying power itself, and which, in the absence of the latter, makes it possible to operate a buffer battery circuit (BT) for the continuity of the power supply of the block (BOR) and of the memory (RAM) and activates the processor block (CPU) for the conservation of the condition operational of the device; said external memory (ME) transferring in said memory (RAM) the user programs for operational processing of the welding control and receiving in memory the data of the diagnosis and of

  the operational history of the device.

  The invention is explained in more detail below using the attached drawing, which schematically illustrates in a single figure a block diagram of the improved control device according to the invention, according to an exemplary embodiment and an embodiment presented

  only by way of nonlimiting example.

  The following description, for reasons of

  summary and economy of exposure, omits the punctual and detailed explanation of the structure and functions of the known type of control device, given that they are well known to technicians in this sector, and that we must not identify, describe and claim that perfecting the same device that forms

the object of the present invention.

  With reference to the attached figure, a known type of welding control device comprises an INAL analog data input block for uses controlled by the control device and the outside world 1. These analog inputs make it possible to measure the physical quantities necessary for the control of the welding point, in particular the measurement of the amperometric strip for reading the secondary welding current, the measurement of the value of the network voltage of the power unit (of the initiator of the welding machine ), the measurement of the voltage value

  on the electrodes during welding.

  An IODIG block for communication with means external to the control device, by means of a few serial and parallel gates processed directly by a processor block CPU. In particular, the IODIG block includes a serial door 2 for the connection, via a special opto-isolated interface IR, represented by the hatched line in the figure, of the control device to the local welding network 3, a door serial 4 for connection of the device to various devices via its own "general purpose" interface and a parallel door 5 for connection via

  IP interface with a printer 6.

  A ROM memory is provided in the form, for example, of two EPROM memories which carry the internal firmware program for the internal, cyclic and operational functions of the control device. A RAM memory constitutes the working memory and data storage space, produced for example by two CMOS chips (microchips) for a total of 256KByte at 16 bit, is intended to keep and make available a user cycle processing program specific solder to which the device

control is intended.

  Said INAL, IODIG, RAM and ROM memory blocks are connected via a bus 7 to said CPU processor block, so called because it is

  achievable with one or more microprocessors.

  In turn, the processor block CPU is in communication via the IT interface with a door 8 for the connection, momentary and when it is necessary, with an external portable terminal for manual programming by direct digitization, of known type, called small keyboard T. In addition, the processor block CPU directly processes a display with display D which, preferably in the form of a digital indicator, displays, for example, the values of the current recorded during the last welding and

any coded alarms.

  The CPU processor block finally processes signals at output 9 and input 10 for control and

  control, via opto circuits

  respective isolators OIS and COND interfaces, of a welding machine MS and its initiator lo relative IS, schematically represented in the attached figure in the form of blocks in the outside world 1 to the control device. Without going into the details of the known functions, the CPU processor block processes, for example, all the diagnostics of the control device and the slave welding machine, the alarms and the pre-alarms, the input / output of data and signals , serial ports, IR interface of network 3 and IT of the small keyboard T, calculates the effective welding current for each of the operational cycles, produces pulses for the IS initiator, determines the angle of initiation of the electrodes for the next cycle, controls the electric valves of the welding machine, provides for the closing and opening of the electrode clamps, controls the condition of the electrodes and the flow of cooling water, etc ..., which are all necessary functions known per se, established by said internal program on EPROM and by the user program available from network 3 or loaded manually into RAM via the small keyboard T. The control device it naturally comprises a supply circuit, represented diagrammatically in the figure by the block AL, which provides for several supply lines 11 at various voltages for the different blocks and

device circuits.

  In accordance with the present invention, the improved welding control device in question further comprises connector means 12 for the connection which can be removed from an external memory ME with said bus 7 and said processor unit CPU. Said external memory ME has the function of transferring into said RAM memory the user programs for operational processing of the welding control and receives in memory the data of the diagnosis and of the history

operational of the device.

  Advantageously and preferably said external memory ME is constituted by a cartridge with semiconductor memory, with its own processing program in firmware and its own autonomous battery power supply, called commercially and conventionally "memory-card" (memory card) because of its appearance and dimensions comparable to that of a credit card. The connector 12 therefore consists of a standard 68 pin connector. For this purpose we can use such memory cartridges with a capacity of 4MByte at 16 bit, of which only a very small part (about 2KByte) is used by the user program to set up, the rest is available to the processor block CPU for storing diagnostic data and operational history. This remarkable capacity of said external memory ME allows the memorization of more than one user program, and can therefore constitute a small bank of handy programs or, on the contrary, be intended

  to the simple memory of the diagnostic data.

  One can also advantageously adopt, with the consequent adaptations of program, also commercial memory cartridges able to fulfill various functions as provided with means of connection and dialogue external to the device, modem or peripherals, useful, for example , for remote control

  functions performed by the device.

  The improved device in question furthermore includes a BOR clock block which supplies references to absolute real time to said CPU processor block, for the timing of operational processes, for diagnosis or for operational history, achievable by means of a simple chip, as well as a power supply control block PF (Power Failure = power failure), provided with sensor means 13 of the power supply itself, and which, in the absence of the latter, makes it capable of operating a buffer battery circuit BT, for example a lithium battery, for the continuity of supply of the block BOR and of the RAM memory and which activates the processor block CPU for the conservation of the operational condition of the device. In accordance with the invention, it is thus obtained that the improved control device can operate, if it is useful or necessary, isolated from the network 3, because it is possible to provide for the installation of user programs by simple insertion and fast external memory ME which can also serve, as already mentioned, mass memory for diagnostic data and operational history, which can be printed via the printer 6 or kept in archive. The same ME external memory can be used, inserted and de-inserted, to set up the same program on different isolated welding control devices and a user program bank can be created for all requirements and needs, which can even be treated by personnel who are not highly qualified. The forecast of the BOR clock block supplements the supply to the processor block CPU of the necessary time references, which until now were only made available by the remote processing unit of the network 3, finally the buffer battery BT allows the conservation of the operational condition in the event of sudden power supply failures, which avoids the loss, of the data certainly, but also of the user program in the RAM memory (the external memory ME is provided with its own power supply) or the wrong recovery from the program

  when the power returns.

  The improved control device in question naturally retains the IR interface and door 2 to allow its connection in the network 3, as does the IT interface and door 8 for the small keyboard T, always useful in the event of intervention. for contiguous program or local control changes in the event of an alarm

or in other similar cases.

  In accordance with the invention described, it is therefore possible to obtain the greatest installation capacity, capable of producing welding lines even with only one or two welding machines and their relative control devices according to the invention, always connectable in the network. , but operational in "stand alone" condition, that is to say isolated. We thus obtain the possibility of reducing installation costs enormously and we can avoid the structural complexity of the systems in the network, we can plan to quickly replace broken devices by avoiding the long delays of manual reprogramming and by preserving the condition operational and timing at the external memory ME which can be

multiplied and transferred.

  The invention thus conceived is susceptible of numerous modifications and variants, which all fall within the domain of the same inventive concept. In addition, all details may be replaced by technically equivalent elements. For example, the external memory ME is practically also achievable through the use, like the connector 12, of conventional reading means (driver) for floppy disks or for magnetic tapes or for optical disks, always recognizable by the processor block CPU as extension RAM memory, but this solution is not recommended because of the complexity of the mechanical means required and of the relative control programs and because of the fact that the strong magnetic fields present near the welding machines make the use of conventional magnetic supports very little

sure.

  In practice, it is obviously possible to make modifications and / or improvements which, however, all fall within

  claims protection limits

following.

Claims (4)

  1. An improved welding control device, of the type which includes an analog data input block (INAL) for uses controlled by the control device and the outside world, a block (IODIG) for communication with means outside the device control, a memory (ROM) and a memory (RAM), connected via a bus (7) and a processor block (CPU), in turn in communication via an interface (IT ) with a door (8) for connection with an external portable terminal for manual programming called a small keyboard (T), for signal processing at output (9) and at input (10) for command and control, by through their own opto-isolator circuits (OIS) and their own interfaces (COND), a welding machine (MS) and its relative initiator (IS), characterized in that it comprises a connector means ( 12) for the connection that can be removed from an external memory (ME) with said bus (7) and with said processor block (BPU), a clock block (BOR) which provides directly to said processor block (CPU) references to absolute real time, for the timing of operational processes, for diagnosis and history operational, a network supply control block (PF), which is provided with sensor means (13) of the supply itself, and which, in the absence of the latter, makes it capable of operating a battery circuit buffer (BT) for the supply continuity of the block (BOR) and of the memory (RAM) and which activates the processor block (CPU) for the conservation of the operational condition of the device; said external memory (ME) transferring in said memory (RAM) the user programs for operational processing of the weld control and receiving in memory the diagnostic and history data operational of the device.   2. An improved device, according to claim 1, characterized in that said external memory (ME) consists of a cartridge with a semiconductor memory, its own processing program in firmware and its own autonomous power supply.   3. An improved device, according to claim 2, characterized in that said external memory (ME) is provided with means of connection and dialogue outside the   device with distant devices.   4. An improved device, in accordance with   previous claims and in accordance with this   which is described and illustrated with reference to the figures in the attached drawing and for the purposes indicated.