Modular welding equipment

Welding equipment that includes a tooling cart for transferring interchangeable tooling modules to a welding machine. A latch is mounted to the welding machine for latching the tooling cart to the welding machine, and a latch is provided for latching the tooling modules onto the tooling cart. A two-piece tooling cart includes a removable upper section for securing tooling modules thereto and a reusable lower section for use with other tooling modules. A welding method permits operation of a welding machine using a user interface that permits modular programming of at least one operational sequence of welding machine valves and weld operations for a variety of different tooling modules. An operator inputs a new sequence of operations using the user interface rather than having to rewrite ladder logic just to switch over the welding machine to use with a different tooling module.

FIELD OF THE INVENTION

This invention relates to welding equipment of the type used in manufacturing plants for production of welded parts. More particularly, it relates to electric welding machines, such as resistance welders and metal-inert gas (MIG) welders, and related equipment.

BACKGROUND OF THE INVENTION

It has been a common practice in the welding machine industry to build welding machines with custom tooling as an integral part of the welding machine. In this practice, especially in connection with resistance and MIG welding machines, each machine is dedicated to the manufacture of a particular part and is not usable for manufacture of other parts. The working area of such a dedicated machine includes an attached assembly of fixtures and tools specifically made, located and adjusted to produce the parts to which the machine is dedicated. The entire machine, from heavy frame to built-in precision fixtures is treated as capital equipment on the financial books of the purchaser. When the parts produced by the dedicated machine are no longer needed, the entire machine is generally scrapped.

Previously, there had been a longstanding need in the industry to overcome the disadvantages which accompany the practice of using dedicated welding machines such as the economic loss from scrapping the entire machine when the tools and fixtures are no longer usable because of wear and tear or because of termination of production of the part to which the machine is dedicated. A general solution to this problem is disclosed in U.S. Pat. No. 6,512,195 which discloses an electric welding machine that has a base operating machine which can accept different tooling modules so that only the tooling module and not the entire welding machine can be replaced when switching between different welding programs or operations.

In the welding machine of the U.S. Pat. No. 6,512,195 patent, the tooling module can be transferred to and from the base operating machine from a module transfer cart, or tooling cart, that is useful in transporting and storing the tooling module when not in use. To connect a particular tooling module to the base operating machine for use in welding parts, the tooling cart containing the tooling module is wheeled up to the base operating machine. A pair of alignment pins on the tooling cart engage and insert into corresponding alignment sockets on the base operating machine. This helps insure proper alignment of the cart and base operating machine so that the tooling module can be slid off the cart and onto the base operating machine. Although this arrangement provides vertical and lateral alignment of the tooling cart and base operating machine, it still allows for relative movement of the tooling cart toward and away from the base operating machine during tooling module transfer. Additionally, this arrangement does not provide any means for positively latching the tooling module to the tooling cart to maintain the tooling module in place and prevent the tooling module from shifting on the cart as the tooling cart is moved. When a particular tooling module is not in use on a base operating machine, it is typically stored on a tooling cart until needed. This enables easy transportation and storage of the tooling module without requiring heavy lifting equipment. However, this arrangement does require a dedicated cart for each tooling module.

When switching between tooling modules, new control programming is typically required for the welding machine. As is known, welding machines typically include a programmable logic controller (PLC) that is programmed to carry out one or more specific welding sequences in which the PLC controls operation of both the welding controller and the various solenoid valves used to drive pneumatic cylinders or other actuators that load, manipulate, weld, and unload a part. Programming of the PLC has typically been done using ladder logic, with a separate set of ladder logic being written and loaded into the PLC for each different tooling module used.

It is a general object of this invention to improve upon some of the features of the modular welding machines discussed above.

SUMMARY OF THE INVENTION

In accordance with one aspect of this invention, there is provided modular welding equipment that comprises (i) a welding machine having a base operating machine and a tooling module supported by the base operating machine, (ii) a tooling cart engageable with the welding machine, and (iii) a tooling cart latch that includes a first latch member on the base operating machine and a second latch member on the tooling cart. The tooling cart can be used to transport one of a number of different tooling modules to and from the base operating machine. During loading and unloading of a tooling module on and off the base operating machine, the tooling cart can be latched to the base operating machine by engagement of the latch members. In this way, relative movement between the tooling cart and base operating machine is inhibited during loading and unloading of the tooling module.

In accordance with another aspect of the invention, there is provided a tooling cart for use with a tooling module, wherein a tooling module latch is provided to secure the tooling module on the cart during transportation and storage of the tooling module. The tooling module latch preferably is designed so that the tooling module can only be unlatched when the tooling cart is connected in position to the base operating machine.

According to another aspect of the present invention, a welding tooling cart is provided which includes a reusable lower section having a base and wheels along with a separate, upper section that includes a frame for supporting the tooling module. The lower section includes a plurality of locators and the upper section aligns with and fits over the locators. Then, when a particular tooling module is not currently in use, it can be stored on the upper section of the cart which is removed from the wheeled base so that the lower section can be re-used with another upper section and tooling module.

According to yet another aspect of this invention, there is provided a method of operating a welding machine using a user interface that permits modular programming of one or more operational sequences of welding machine valves and weld operations for a variety of different tooling modules. The method facilitates switching over to a different tooling module wherein an operator inputs a new sequence of operations using the user interface rather than rewriting ladder logic.

A complete understanding of this invention may be obtained from the detailed description that follows taken with the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The description that follows will set forth the best mode for carrying out the invention by describing illustrative embodiments of the inventive modular welding machine as presently contemplated. This invention is especially adapted for use with electric welding machines of all types, but can be used in conjunction with other types of welders. This disclosure relates to various improvements to the modular welding machine disclosed in U.S. Pat. No. 6,512,195, which is assigned to the assignee hereof and which is incorporated by reference herein in its entirety. It will be appreciated as the description proceeds that the invention is useful in a wide variety of applications and may be realized in many different embodiments.

Referring now toFIGS. 1 and 2, an exemplary embodiment of modular welding equipment according to this invention includes a welding machine10, which is a resistance welder of the spot welding type. The welding machine10comprises, in general, a base operating machine12and a tooling module14shown in its installed location in the base operating machine12. The base operating machine12comprises, in general, a machine frame16, and at least one welding transformer17. The tooling module14comprises a module frame15which supports the tooling components required for a particular welding job or product which is to be run on the machine12.

The tooling module14is installed in the machine12as a unit and is removable as a unit as needed for maintenance, repair or for replacement by another tooling module. The tooling module14is adapted for a specific job only and several different tooling modules may be kept in standby condition which are tooled for particular production jobs which may be needed in the future. The base operating machine12and the tooling module14will be described in greater detail below.

The machine frame16comprises a table structure that includes a tooling module station at an upper location on the machine frame16. The tooling module station receives the tooling module14and, for this purpose, includes a module support guide or rack19that enables the tooling module to be rolled into and out of the tooling module station. The table structure includes front legs22with shoe plates22′, rear legs24, cross beams26, front to rear longitudinal beams28and upper longitudinal beams32. A table plate34is supported on the upper longitudinal beams32. A pair of oppositely disposed rear posts38extend upwardly from bolt plates38′ mounted on the longitudinal beams32. A support beam42extends transversely of the frame16between posts38.

The base operating machine12includes the support rack19for supporting the tooling module14, wherein the support rack19comprises the table plate34and guide means or a roller guide66. The guide means66comprises a pair of rails68which extend parallel with each other in the front to rear direction of the machine frame16. Each rail68includes a flange plate72mounted on the inner side of the rail68and each rail68also includes a plurality of rollers or roller bearings74having a stationary shaft extending through the flange plate72and rail68and secured thereto. The rails68are spaced apart laterally so that a bottom plate76of the module14is supported on the two sets of rollers74and retained in a centered position between the flange plates72. The rails68facilitate the removal and installation of the tooling module14in the base operating machine12.

The tooling module14comprises the module frame15which includes the bottom plate76with a pair of vertical posts84supported thereon in laterally spaced arrangement. Lower triangular brackets85support the vertical posts84on the bottom plate76. The posts84together with triangular brackets86support a top plate88which is located above the bottom plate76. The upper tooling is mounted to the top plate88and comprises a pair of weld guns92. The lower tooling of the module14comprises a pair of electrodes98, which are supported on the bottom plate76.

In order to facilitate the installation and removal of the tooling module14from the base operating machine12, a tooling cart or module transfer cart202is provided as shown in an unlatched location inFIG. 1. The cart202is part of the welding equipment described herein and comprises a rectangular frame204which is mounted on a set of casters206. For supporting the tooling module14on the cart202, a guide means or roller guide266, which comprises rails268, side plates and roller bearings274mounted on the top of the frame204in the same manner as described with reference to the guide means66in the support rack19of the welding machine10. The forward end of the cart202is provided with a pair of alignment pins208which extend forwardly from the front of the cart frame204. A pair of alignment sockets212are disposed on the machine frame16which are aligned for coaction with the pins208when the cart202is positioned so that the guide rails268on the cart202are in alignment with the guide rails68on the support rack19. When the cart202is positioned so that the pins208are fully inserted into the sockets212, the tooling module14is manually pushed off the cart202from its uninstalled location, onto the support rack19on the base operating machine12to its installed position or location.

A tooling cart latch is used to secure the tooling cart202in a latched location with respect to the base operating machine12. In the illustrated embodiment, two latches are used, each of which includes a latch plate210that is mounted on the vertical front frame members of the cart202and a latch110that is attached to the base operating machine12at one of the two tubular frame members or front legs22. Thus, when the cart202is wheeled up to the machine12to transfer a tooling module14to or from the cart202, the cart202will move into engagement with the latches110to lock the cart202in proper positioning against the base operating machine12in its latched location. As will be described in further detail below, the latches110each include a spring loaded first latch member that engages its associated latch plate210to secure the cart in place. However, it is also contemplated that the latches110could also cooperate directly with a different portion of the tooling cart202such as the frame thereof or some other feature besides the latch plates210.

The two latches110can be identical, the only difference being that one is inverted when being bolted to the base operating machine12, as indicated inFIG. 2. Accordingly, only one latch110will be described and it will be appreciated that the description applies equally to both latches110.

FIGS. 3 through 7depict top views of the latch110as it would be oriented when mounted on the base operating machine12andFIGS. 8 and 9provide perspective and front views, respectively, of the latch110. The latch110is attached via its mounting plate112that includes two or more clearance holes114through which bolts (not shown) are placed to fasten it to the framework of the base operating machine frame16. Any other suitable means could be used to attach the latch110to the machine frame16. Extending generally perpendicularly from the mounting plate112is a bracket116in the form of a flat plate having an end section118that is bent or angled out of the plane of the remainder of the bracket116. This provides a guide surface120to center the cart202as it approaches the base operating machine12from its unlatched location so that the cart202need not be in perfect alignment as it is brought into contact with the machine12into its latched location. This can also help achieve alignment of the pins208of the cart202with the sockets212or can eliminate the need for the alignment pins208and sockets212altogether.

The bracket116includes an aperture or hole122at a central location near the bend in the bracket116that defines the angled end section118. On the side of the bracket116opposite the guide surface120side is a spring housing124that is welded, threaded, press-fit, or otherwise rigidly attached to the bracket116about the hole122(i.e. substantially concentric with the hole122). The spring housing124is basically a hollow component that has a cylindrical shape with a back wall126that serves to retain a spring128within the housing124. The spring128is a helical compression spring mounted on a shaft130that extends through the housing124. The shaft130is connected at one end to a handle132or knob and at the other end to a cylindrical end piece or head134located within the hole122in the bracket116. It is contemplated that the shaft130and head134could be one integral component instead of being separately attached and such arrangements are equivalent. The head134has a back surface or shoulder136against which the spring128presses to force the shaft130and head134outwardly through the hole122in the bracket116. The head134also includes an angled bearing surface138at its exposed or free end. Extending perpendicularly through the shaft130near the knob132, and between the spring housing124and the knob132, is a pin140that extends transversely through a portion of the shaft130and engages a cam surface142at the free end of the spring housing124. The spring128operates to bias the head134and shaft130outwardly of the spring housing124in an inboard direction so that the angled bearing surface138is positioned beyond or inboard of the hole122in the bracket116at an exposed location. The extent of movement of the head134and shaft130in this biased direction is limited by engagement of the pin140with a detent144in the cam surface142. Thus, the head134and shaft130are spring loaded, with these components being movable against the spring bias by pulling on the knob132.

As shown inFIGS. 4 and 5, in use, when the cart202is moved up to the base operating machine12from its unlatched location to its latched location, the latch plates210mounted on the cart202engage the angled bearing surfaces138of the heads134of the latches110as the cart202is advanced toward and eventually into contact with the machine10. This causes the head134and shaft130to retract against the bias of the spring128, as shown inFIG. 4. Once the cart202has been moved fully into engagement with the machine12, the latch plate210moves past the head134, allowing it to spring back to its original position, and thereby latching the cart202in place against the machine, as shown inFIG. 5. The tooling module14can then be transferred between the cart202and machine16.

Referring now toFIG. 6, when the operator is ready to remove the cart202from the machine10, the latch110is released by pulling the knob132and turning it 180° so that the angled bearing surface138now faces the opposite direction. As the cart202is pulled away from the machine10, the latch plate210again engages the angled bearing surface138, forcing the head134and shaft130to move outwardly while the cart202is removed. This is shown inFIG. 7. The knob132can then be rotated back to its original position so that it will be properly positioned for whenever the cart202is again used for transferring another tooling module. As will be appreciated, the V-shaped profiled cam surface142and detent144shown in these figures allows the angled bearing surface138to be maintained in either of the two 180° orientations.

Referring now toFIGS. 10 and 11, there is shown another embodiment302of the tooling cart in which it includes a safety tooling module latch150to prevent the tooling module (14ofFIG. 1) from being moved off a tooling cart302unless and until the tooling cart302is properly positioned at the base operating machine12. The tooling cart302can be similar to the tooling cart202ofFIG. 1, except as described below. When the tooling module (not shown) is situated on top of the cart302, a module latch member such as a locating pin or shot pin152is used to latch it to the cart302to prevent the tooling module14from rolling off of the cart302. The shot pin152is dropped down through a hole (not shown) in the tooling module base plate or frame (not shown), and this shot pin152extends longitudinally in a vertical direction into a vertically extending passage of a shot pin block154on the cart302where it is latched. Until this pin152is unlatched, it cannot be removed and the tooling module cannot therefore be rolled off the cart302. The shot pin152is latched using a cart latch member of the tooling module latch150such as a probing rod156, which extends forward of the cart302and is spring loaded into the position shown inFIG. 10in a transversely extending passage of the block154.

The probing rod156is mounted on a frame member such as a rectangular upper fork lift tube304of the cart302. In its biased position as shown, the rod156extends through a mounting block158and into the shot pin block154wherein the rod156selectively engages an engagement recess such as a reduced diameter groove160of the shot pin152which is shown inFIG. 11. With the probing rod156transversely extending with respect to and engaging the shot pin152in this groove160, the shot pin152cannot then be removed due to the interference or engagement between the probing rod156and end portion of the shot pin152.

With reference toFIG. 11, when the cart202is brought into engagement with the welding machine (10inFIG. 1), the probing rod156engages a portion of the machine10, such as the machine frame16, and is pushed backwards against the bias force of a spring162. The probe rod156continues moving backwards through the shot pin block154until the cart302is properly in its latched position at the machine10(e.g., using the tooling cart latch discussed in connection withFIGS. 1-9). At this point, a disengagement recess164in the probing rod156will be substantially adjacent and aligned with the vertical passage and shot pin152in the shot pin block154so that there is no longer any interference or interengagement of the probing rod156with the shot pin152, and the shot pin152can therefore be removed to thereby unlatch the tooling module. As shown inFIG. 11, the probing rod156may be an assembly of two separate rods166,168coupled together with a coupling nut170and jam nuts172on either end thereof to provide a shoulder against which the spring162locates. Alternatively, however, it is contemplated that a single rod could be used with an integral annular flange or a circlip fastener or the like to provide a shoulder for cooperating with the spring162.

Typically, tooling modules are stored on their associated cart302when not in use. Rather than storing them on an entire cart, such that one full cart (including casters and all) is needed for each tooling module, the cart302can be made in two sections, as shown inFIG. 10. An upper portion or section has a framework including laterally opposed forklift tubes304for supporting roller guide366including its guide rails368and rollers374. The upper section also includes a laterally extending cross-member306, which connects rear ends of the fork tubes304, and downwardly extending tubular legs308at each of the four corners of the cart302. A lower portion or section of the cart302includes a cart base312or truck, which has its own framework including laterally opposed and longitudinally extending forklift tubes314and longitudinally opposed and laterally extending cross-members316. The base312also includes fixed casters318, swivel casters320, and levelers322, as well as locators324at each of the four corners. The locators324are preferably semi-spherical in shape and are aligned with and easily mate with the open ends of the tubular legs308of the upper section so that the upper section normally sits on the cart base312and stays in place due to its weight, but can be lifted up off the cart base312. As such, open ends of the tubular legs308act as female locators for cooperating with the base locators324which fit partially up into the tubular legs308. This arrangement permits the tooling module to be left on the upper cart section so that it can be stored in this manner on the upper section, while the cart base312is then available for use with other tooling modules and upper cart sections (not shown).

Those of ordinary skill in the art of welding machine technology recognize that the operation of welding machines is often controlled using a programmable logic controller (PLC). Each tooling module operates under program control provided by the programmable logic controller (PLC), wherein a stored computer program is provided in the PLC corresponding to each different tooling module. When a module is installed in the base operating machine, the program for running the module may be manually selected by the operator by a program selector in a control cabinet of the machine (not shown). In the past, programming of the PLC has typically been done using ladder logic, with the PLC controlling operation of both the welding controller and the various solenoid valves used to drive pneumatic cylinders or other actuators that load, manipulate, weld, and unload a part. For each different tooling module used, a separate set of ladder logic is written and loaded into the PLC. However, for the welding machine10of the disclosed embodiment, an improved operator interface is provided which presents the operator with a simplified user interface that permits programming of the necessary sequencing of valves and weld operations to accomplish the required task for any particular tooling module. Thus, when switching over to a different tooling module, new ladder logic need not be specifically written for the new tooling module, but rather, just a new sequence of operations using the interface.

As described with respect to the welding machine of the incorporated U.S. Pat. No. 6,512,195 patent, the PLC can be a Nematron™ PTC5800 and the HMI can be a Nematron™ 5.7 inch touchscreen, both of which are available from Nematron Corporation of Ann Arbor, Mich., USA (www.nematron.com). The HMI touchscreen is used by the machine operator to input the sequencing of operations for a particular tooling module. An exemplary touchscreen input display is shown inFIG. 12. It is through this user interface that the operator can define the proper sequencing of valve and welding operations for the tooling unit without having to write direct ladder logic for the PLC.

Any given overall welding cycle (or Auto Cycle) consists of a number of sequences that can be entered by the operator through the touchscreen user interface. For example, the welding machine might permit up to eight sequences for a single welding cycle in which case eight of these sequence definition screens would be filled out by the operator. The sequence number (1-8) may be displayed at the top, center of the touchscreen, and on either side of this are previous and next buttons to allow the operator to move forward or backward through the sequences. For each sequence, there are eleven possible command and data entries, with a twelfth entry at the bottom used to specify whether there are more sequences to enter or whether the operator is done with the welding cycle definition. The programming of each of these twelve entries is as follows in accordance with an exemplary method of the present invention:

Step one: Select “Valve On” command (range: 0-7); each number corresponds to a solenoid valve on the base machine. This valve could control a pneumatic cylinder on the tooling module such as a weld cylinder, weld cylinder slide, clamp cylinder, locate cylinder, unload part cylinder. Enter 0 if no command is used. The master PLC program will check that all machine inputs and outputs are okay to start and continue machine cycle.

Step Two: Select “Delay Timer” command (range: 0.0 to 3.00 sec.); this timer is the delay between the “Valve On” above this command and the “Valve On” below this command. Enter 0 if no delay is used.

Step Three: Select “Valve On” command (range: 0-7); each number corresponds to a solenoid valve on the base machine. This valve could control a pneumatic cylinder on the tooling module such as a weld cylinder, weld cylinder slide, clamp cylinder, locate cylinder, unload part cylinder. Enter 0 if no command is used.

Step Four: Select “Delay Timer” command (range: 0.0 to 3.00 sec.); this timer is the delay between the “Valve On” above this command and the “Valve On” below this command. Enter 0 if no delay is used.

Step Five: Select “Input On” and enter input (range: 0-16) that is required to be “on” at this point in the sequence. The master PLC program will check for this input to go on and off each auto cycle. Enter 0 if input check is not desired at this point in Auto Cycle.

Step Six: Select “Input On” and enter input (range: 0-16) that is required to be “on” at this point in the sequence. The master PLC program will check for this input to go on and off each auto cycle. Enter 0 if input check is not desired at this point in Auto Cycle.

Step Seven: Select “Weld Such.” and enter the weld schedule number (range: 0-63) that is required for this weld. The master PLC program will turn on the binary select, weld enable, and initiate weld outputs that interface with the weld controller. It will also confirm the weld complete signal from the weld controller. Enter 0 if no weld is desired at this point in Auto Cycle.

Step Eight: Select “Valve Off” command (range: 0-7); each number corresponds to a solenoid valve on the base machine. This valve could control a pneumatic cylinder on the tooling module such as a weld cylinder, weld cylinder slide, clamp cylinder, locate cylinder, unload part cylinder. Enter 0 if no command is used.

Step Nine: Select “Delay Timer” command (range: 0.0 to 3.00 sec.); this timer is the delay between the “Valve Off” above this command and the “Valve Off” below this command. Enter 0 if no delay is used.

Step Ten: Select “Valve Off” command (range: 0-7); each number corresponds to a solenoid valve on the base machine. This valve could control a pneumatic cylinder on the tooling module such as a weld cylinder, weld cylinder slide, clamp cylinder, locate cylinder, unload part cylinder. Enter 0 if no command is used.

Step Eleven: Select “Delay Timer” command (range: 0.0 to 3.00 sec.); this timer is the delay between the “Valve Off” above this command and the “Valve Off” below this command. Enter 0 if no delay is used.

Step Twelve: Select “More=1, Done=0”; Enter 1 to choose to have this sequence linked to the next sequence to follow. Enter 0 to choose to “End” the Auto Sequence. The master PLC program will complete the auto cycle, counters will display completed part in batch counter, tip counters, and master counter. Selecting a “Save Seq.” button saves changes to the master PLC program memory for each sequence.

The programming of the HMI and PLC needed to provide these display screens and receive the input and use it to control the welding machine in the desired manner is routine and all within the level of skill in the art.

It will thus be apparent that there has been provided in accordance with this invention welding equipment and a welding method that achieve the aims and advantages specified herein. It will, of course, be understood that the forgoing description is of preferred exemplary embodiments of the invention and that the invention is not limited to the specific embodiments shown. Various changes and modifications will become apparent to those skilled in the art. All such changes and modifications are intended to be within the scope of this invention.