CA1111508A - Apparatus and method for making electrical resistance welds in a storage battery - Google Patents
Apparatus and method for making electrical resistance welds in a storage batteryInfo
- Publication number
- CA1111508A CA1111508A CA305,400A CA305400A CA1111508A CA 1111508 A CA1111508 A CA 1111508A CA 305400 A CA305400 A CA 305400A CA 1111508 A CA1111508 A CA 1111508A
- Authority
- CA
- Canada
- Prior art keywords
- lugs
- current
- welding
- battery
- resistance
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K11/00—Resistance welding; Severing by resistance heating
- B23K11/24—Electric supply or control circuits therefor
- B23K11/25—Monitoring devices
- B23K11/252—Monitoring devices using digital means
- B23K11/256—Monitoring devices using digital means the measured parameter being the inter-electrode electrical resistance
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Connection Of Batteries Or Terminals (AREA)
Abstract
Abstract of the Disclosure An apparatus and method for making reliable and repeatable welds between lead battery lugs disposed on either side of a plastic partition. An instrument measures the resistance of the welding jaws, electrode tips and contact of the tips with the battery lugs and sends this information to an interface controller where the amount of current required to generate the heat to make a reliable weld is determined from the resistance measurement. Information is then sent to a transformer controller which energizes a transformer to provide the correct amount of current to the welding jaws. While the welding is in progress, an instrument measures the current flowing through the electrode tips and lugs and this infor-mation is sent to the interface controller for comparison with the determined value. After the weld is complete, the resistance is again measured and, if the weld is found to be inadequate, the battery is marked as a reject and a reject mechanism discards the battery from further process-ing in the assembly line.
Description
5~)8 Background of the Invention Conventional electrical resistance welders for use with lead storage batteries can be thought of as com-prising an electrode means for contacting the lugs as parts to be welded together and for conducting current thereto, and power means for supplying a fixed amount of current to the electrode means. The electrode means ~k ~' comprises at least two welding jaws, each having an electrode tip portion. The welding jaws move together to press the lugs together with the electrode tip portions making contact with the lugs. These conventional electrical resistance welders ignore some of the variables present during the welding process that effect the making of constant and repeatable welds. For example, when the electrode tips move with the welding jaws to contact the lugs, the exact electrical res;stance of the combination of welding jaws, electrode tips and the contacts that the tips make with the lugs is unknown. Also, surface oxidation, lug composi-tion, and the pressure of the jaws on the parts are all impor-tant factors in determining the resistance. In addition, a certain amount of heat is dissipated into the atmosphere from the lugs and parts of the welding apparatus. Hence, if current is applied to the electrode tips without factoring in the variation of resistance from weld to weld, then constant repeat-able welds become more difficult if not impossible to attain.
Apparatuses and methods for making intercell connections within batteries through the use of electrical resistance welding are disclosed in U. S. Patent Nos. 3,313!658; 3,388,005;
3,589,948; 3,687,734; 3,723,699; 3,793,086; 3,798,Q71; and 3,869,316. Methods for making battery terminals are described in U. S. Patent Nos. 3,303,056i 3,457,118; 3,849,203; and 3,874,933. None of these references disclose provisions or methods for measuring the resistance between the weldi~ng means and the lugs for each weld which is to take place, and usin~
this measurement to control the amount of current which is to be delivered to the lug contact surfaces where the weld will take place.
~2 y Summary of the Invention According to one aspect of the invention there is provided an electrical resistance welding apparatus for making repeatable welds in lead storage batteries between battery lugs disposed on opposite sides of plastic partitions and pressed together to contact one another therethrough, comprising: (a) welding means for welding together a plurality of battery lugs, comprising: (i~
electrode means for contacting said lugs and conducting current thereto; and (ii) power means electrically con-nected to said electrode means for supplying a fixed amount of current to said electrode means for conduction to said lugs; (b) electrical resistance measuring means electrically connected across said power means for meas-uring the electrical resistance of said electrode means in contact with said lugs; and (c) an interface controller electrically connected to said resistance measuring means and to said welding means for determining said fixed amount of current and the time over which said current is to flow in response to said measurement of electrical resistance, and for communicating the same to said welding means, According to another aspect of the invention there is provided a method of making repeatable welds in lead storage batteries between battery lugs disposed on oppo-site sides of plastic partitions and pressed together to make contact therethrough, comprising the steps of: (a) providing welding means for applying current to said lugs;
~b) moving said welding means to contact said lugs; (c) measuring the electrical resistance of the lugs through a portion of said welding means in contact with said lugs; (d) determining the amount and time of current flow required to form said welds in response to said resist-ance measurement (e) controlling the amount and time of current flow delivered by said welding means to said lugs in response to said determination; and (f) withdrawing said welding means from said lugs.
Applicant's invention is based on the following equation:
H = (I ) (R) (T) (K) where H equals the heat needed for a weld; I2 equals the current squared; R equals the resistance of the parts involved in making the weld; T equals the time needed over which the current is applied to make the weld; and K
equals a proportionality factor relating H to the other factors, K relating to the heat dissipated into the atmosphere from the parts involved in making the weld.
A good weld can not be made without the proper amount of current being delivered within the right amount of time. If a certain amount of power is not present, then the heat can not be generated to melt the lead and create a fusion zone at the point where contact is made between the lugs. In order to be sure that the proper amount of current is delivered, the resistance of the electrode means in contact with the parts or lugs to be welded together must be known. This resistance can be made of several factors, for example, the resistance of the welding jaws to the electrodes tips; the resistance of the electrode tips to the welding surface on the lugs;
surface oxidation of the lead lugs; the composition of the various parts; the amount of antimony present; the pressure exerted on the lugs to squeeze them together, etc.
The only factors whlch are undecided once the heat H
D
and the factor K are either analytically or empirically determined are the factors I2, ~, and T. Applicant's system measures R and leaves only I2,T to be determined.
I ,T can be regulated by controlling the transformer output over a period of time. R is determined by the proper measurement of the resistance of the electrode means in contact with the lugs or parts to be welded together.
In the preferred embodiment, the measured resistance values are sent to an interface controller which uses this information to determine the correct amount of current and the time over which the current is to flow. This infor-mation is sent to the transformer controller which then applies a voltage to a transformer primary and a current begins to flow through the parts to be welded together.
In one embodiment of the invention, as the current is flowing during the making of the weld, it is measured by a current analyzer and the current value compared with the current value predicted by the interface controller.
If the measured current is different from the current determined by the interface controller, the control of the transformer through the transformer controller is adjusted by a command by the interface controller.
In the preferred embodiment, after the weld is com-plete, the resistance is remeasured if it is too high, the entire process is repeated. If after the second attempt at welding, the resistance is still too high, an indica-tion is made on the battery by a marking means, such as an inking system. This marking is sensed by a reject mechanism which~ in turn, rejects the battery from further processing.
~1115Q8 It is an advantage of the present invention, at least in preferred forms, that it can provide an electrical resistance welding apparatus for making repeatable welds in lead storage batteries between battery lugs disposed on opposite sides of plastic partitions by measuring the electrical resistance between the lugs that are to be welded together and by controlling the current which flows to make the weld in accordance with the resistance measurement.
It is another advantage of the present invention, at least in preferred forms, that it can provide an electrical resistance welding apparatus which marks those batteries with defective welds determined by the electrical resist-ance measurement.
It is another advantage of the present invention, at least in preferred forms, that it can provide an electrical resistance welding apparatus which automatically rejects batteries with defective welds.
Another advantage of the present invention, at least in preferred forms, is that it can provide an electrical resistance welding apparatus which measures the current flowing between the lugs to be welded together and which has a means of controlling the current delivered to the lugs to ~e welded together in accordance with the current measurement.
It is another advantage of the present invention, at least in preferred forms, that it can provide a method of making repeatable welds in lead storage battery lugs dis-posed on spposite sides of plastic partitions.
It is another advantage of the present invention, at least in preferred forms, that it can provide a method of - 5a -.~
)8 locating batteries with defective welds and rejecting said batteries.
This and other advantages of my invention will become apparent in the following description with reference to the accompanying drawings.
- 5b -. ~ .
Brief Description of the Drawings Fig. 1 is a schematic view of the electrical resistance welder of applicant's invention;
Fig. 2 is a cross-sectional view of the electrodes pressing together the lugc to be welded through a plastic partition, the lines contacting the electrodes representing the electrical connection of an electrical resistance measur ng means to the electrode means.
Detailed Description of the Drawings Although specific forms of the invention have been selected for illustration in the drawings, and the following description is drawn in specific terms for the purpose of describing these forms of the invention, this description is not intended to limit the scope of the invention which is defined in the appended claims.
Referring to the figures, in Fig. 1 a pair of welding jaws 10 and 12, shown in the standby position, are ready to move in the directions of arrows A and A' respectively to engage the battery lugs 14 and 16. The actual portions of the jaws 10 and 12 which engage the lugs are specially-designed protrusions or welding tips 18 and 20. When the welding tips 18 and 20 contact the lugs 14 and 16 and press them together, portions of the lugs are extruded into the opening 22 in the battery partition 24 which is shown disposed between the lugs 14 and 16. In the preferred embodiment shown in Fig. 1, the plastic partition 24 is an internal partition separating the cells o~
a battery; the lugs 14 and 16 are lead lugs y attached to the lead straps 26 and 28 which connect the individual terminal lugs of each of the battery plates within the adjacent cells. As in most modern batteries, the battery case and the partitions are made of a plastic material such as polypropylene. It will be noted that even though the preferred embodiment shows the weld being made between two internal battery lugs disposed on either side of a plastic cell partition, the same apparatus and method could be used to weld an external terminal throush a battery case wall to an internal lug within the battery.
Together, the welding jaws 10 and 12 with the electrode tip portions 18 and 20 comprise the electrode means desig-nated generally 13 which contact the lugs to be welded together and conduct current to the lugs to create the weld. The current is supplied to the electrode means from a power means designated generally 29 and together with the electrode means 13 they form the welding means portion of applicant's welder.
The preferred embodiment power means 29 comprises a current source for providing current to the electrode means such as the transformer designated generally 30 in Fig. 1, and a power control means such as transformer controller 31 in Fig. 1 for controlling the amount of current supplied to the electrode means. The schematic representation of the transformer in Fig. 1 shows that the preferred embodiment transformer is a magnetic core transformer with a primary 32 and secondary 34 shown with a rectified output by the diodes 36 and 38 connected to the ends of the secondary winding 34 and connected together at point 40. Point 40 is shown connected to welding jaw 12 by line 42, and line 44 is connected to welding jaw 10 and center tapped to secondary winding 34.
11115~8 This circuit provides a DC current source to the electrode means.
After the jaws 10 and 12 have contacted the lugs 14 and 16 respectively and extruded portions of the lugs into the aperture 22 to contact one another, but before power is delivered to the lugs for welding, an electrical resist-ance measuring means 46 in Fig. l measures the electrical resistance of the lugs through a portion of the electrode means in contact with the lugs. In Fig. 1, the resistance measuring means 46 is shown receiving inputs from line and arrow 48, and line and arrow 50 connected to points 52 and 54 on lines 42 and 44 respectively. This connection of the resistance measuring means at these points is schematic in nature since the choice of where the resistance is to be measured is critical in determining the actual resistance of the parts to be fused. For example, in Fig. 2, the welding jaws 10 and 12 are shown pressing against the lugs 14 and 16 to cause an extrusion in the aperture 22 and a contact between the lug extruded portions. The line and arrow 48 and the line and arrow 50 of Fig. l are shown as 48' and 50' in Fig. 2 and they are shown contacting the welding jaws at the electrode tip portions 18 and 20.
Hence, in Fig 1, the resistance to be measured will be made up of the following factors: the connection of the welding jaw bodies 10 and 12 to the electrode tip por-tions 18 and 20; the connection between the welding tips 18 and 20 to the lugs 14 and 16; and the contact between the lugs. Fig. 2 shows more clearly how the lugs are ex-truded into aperture 22 where the extruded portions 56 and 58 are shown contacting one another. In an alternate embodiment of applicant's invention where the secondary output of the transformer is S~)~
not rectified, an alternating current is delivered to the lugs and the resistance of the electrode means in contact with the lugs can be made through the transformer.
Referring now to Fig. 1, once the resistance has been measured, it is transmitted by the measuring means to the interface controller 60 by the line and arrow 62. The inter-face controller takes this resistance information and from it determines the amount of current and time over which the current is to flow as determined by the aforementioned equation H = (I2) ~R) (T) (K). This can be accomplished, for example, by having the interface controller 60 obtain the proper current and time from a look-up table which is a memory or storage of different relationships between the resistance that is measured and the proper c.urrent and time that is required to provide a given heat as pre-determined and stored in the interface controller 60. Alternatively, the interface controller could be a microprocessor which is capable of analytically determining the current from the measured resistance and use of the heat e~uation above. The interface controller 60 then sends this information by way of a signal in line and arrow 64 to the welding means such as the transformer controller 31 of the power means which in turn activates the transformer of the power means to deliver a fixed amount of current during a fixed time period to said electrode means. The information sent from the transformer controller 31 to the transformer 30 is sent by line and arrow 66. At the same time, the trans-former controller 31 transmits the information back to the interface controller on line and arrow 68 so th~t it can be compared for accuracy.
~1~1508 Hence, applicant's preferred embodiment measures the resistance of the contact between the lugs contacting one another through the plastic partition wall and, from this information, determines the proper amount of current and duration over which this current should flow in order to provide a thorough and repeatable weld. The method by which this is accomplished is as follows: the battery with the lug surrounding the plastic partition is brought into place between the welding jaws; the welding jaws are then moved in the direction shown by arrow A and A' in Fig. 1 until they contact the lug surfaces upon which pressure is applied and portions of the lug surfaces are extruded into the aperture 22 to contact one another; the resistance of the lugs is then measured through a portion of the welding means in contact with said lugs by the re-sistance measuring means and that information is then sent to the interface controller; the interface controller uses the resistance measurement to determine the proper amount of current and the time which that current is to flow, and sends this information to the transformer controller; the transformer controller controls the amount of current out-put from the transformer and the period of time of the output; the transformer receives the command from the transformer controller and outputs the proper amount of current over a given amount of time; and this current then flows through the electrode means, that is, through the welding jaws, electrode tips and the lug contacts heating the lugs and fusing the lead in the aperture 22. The welding means or welding jaws are then withdrawn to free 3~ the battery. The current delivered to the lugs can ~e either direct or alternating.
In order to insure that the weld is a proper one, f~
~1115Q8 applicant's invention provides for a second measurement of the resistance after the welding process is complete. If a good fusion has taken place, the resistance of the lug connection will be much lower than that of the pre-weld contact, e.g., less than 5 micro-ohms. If the resistance is not within a desirable range, the new value of the resistance can be used to begin the process over again.
If for some reason a good weld cannot be attained as determined by the resistance measurement, then applicant has provided a means in the apparatus for marking and rejecting defective weld batteries. Referring to Fig. 1, marking means 7~ marks those batteries where weld resist-ance values are too high. For example, when the resistance measuring means is told by the interface controller 60 via line and arrow 72 that the final resistance measurement of the attempted weld is too high, then the marking means such as ink system 70 in response to command from the measuring means 46 via line and arrow 75 deposits a few drops of ink in the defective battery in a prominent location on the battery. Of course, any marking means which could designate a battery with a bad weld could be used and the applicant is showing here the preferred embodiment ink system 70. The battery then proceeds down the assembly line where the reject mechanism 77 having been notified in advance of the faulty weld by the resistance measuring means 46 via line and arrow 74 rejects the battery ~rom the conveying system or assembly line so that further processing on that battery would not take place. In this way, batteries that had welds which were not repeatable and up to a certain quality level, for example, less than 5 micro-ohms, would not proceed further and find their way into the marketplace.
B
~11S08 Should the interface controller receive a resistance measurement at any time which did not fall within the look-up table or other means for determining the amount of current and time required to create a proper weld, the interface controller 60 is equipped to signal the resistance measuring means 46 to make another measure-ment. This is indicated by the line and arrow 72.
~ ence, a method is disclosed by applicant whereby batteries with defective welds are detected through resistance measurements, marked as defective and thereby rejected upon detecting the marking.
It may be desirable in the apparatus and method to have a means of correcting the current flowing to the lugs during the actual welding process. Current analyzer 76 in Fig. 1 measures the current flowing through the lugs during the welding process. It is shown electrically connected in series with welding jaw lO at points 54 and 78 connected by a shunt 44 and the information is received via line and arrow 80 and line and arrow 82. When the current has been measured by the current analyzer 76, the information is sent via line and arrow 100 to the interface controller 60 where the measured value of the current is compared with the value of the current determined by the interface controller 60 to be the optimum for creating the weld from 'he value of the resistance as measured by the resistance measuring means 46. The interface controller 60 has the ability to control the transformer controller 31 so that a real time change in the current flowing through the weld can be made by the interface controller 60 of the current, as measured by the current analyzer 76, does not match the current as deter-mined by the interface controller 60. This leads to an even finer control of the process of making the weld.
- 12 - t 1:1115~8 The interface controller receives information from various sources such as the resistance measuring means 46, the transformer controller 31 and the current analyzer 76. It uses the information that it receives to control the welding opera-tion of the entire welding apparatus. For example, upon receipt of information from the resistance measuring instrument 46 as to the resistance of the preweld lug contact, the interface controller selects the appropriate current that must be deliver-ed in a given period of time in order to create enough heat to fuse the lead together in the aperture 22. This information is sent to the transformer controller in such a way as to allow the transformer controller to energize the transformer which ulti-mately provides the current to the lug region. If there is something wrong with the initial or subsequent resistance measurements such that they are not within an acceptable range of resistance measurements, the interface controller can through line and arrow 72, signify the resistance measurement to recycle or to reject. Similarly, after the transformer controller has signaled the transformer to energize, it can tell the inter-face controller via line and arrow 68, what information it provided to the transformer which the interface controller then compares with its own information to determine whether or not the transformer controller is acting correctly. If it is not, it can recycle the process. Also, should the current analyzer 76 provide current information to the interface controller which does not agree with the information determined by the interface controller based on a resistance measurement, the interface controller can e;ther signal the transformer to increase or decrease the power from the transformer in order to bring it in agreement with the value being measured by the current analyzer, or it can ~lllS~)8 stop and recycle the process. Finally, the interface con-troller is capable of providing a signal to the resistance measuring means via line 72 that the final resistance mea-surement in the process was inadequate and that a battery with a defective weld existed. The interface controller signals the resistance measuring means 46 to trigger the ink system 70 to so mark the battery and at the same time it would tell the resistance measuring means to signal the reject mechanism to ~e ready to sense a battery with a defective weld marking so as to reject that battery from further processing. Hence, the interface controller acts as a control for the entire welding apparatus in its func-tion of interfacing with the various instruments and control mechanisms in the apparatus. This fine control of the welding operation provides a means of insuring repeatable welds and high quality control.
It will be understood that various changes in the details, materials and arrangement of parts which have been herein described and illustrated in order to explain the nature of this invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the following claims.
B
Apparatuses and methods for making intercell connections within batteries through the use of electrical resistance welding are disclosed in U. S. Patent Nos. 3,313!658; 3,388,005;
3,589,948; 3,687,734; 3,723,699; 3,793,086; 3,798,Q71; and 3,869,316. Methods for making battery terminals are described in U. S. Patent Nos. 3,303,056i 3,457,118; 3,849,203; and 3,874,933. None of these references disclose provisions or methods for measuring the resistance between the weldi~ng means and the lugs for each weld which is to take place, and usin~
this measurement to control the amount of current which is to be delivered to the lug contact surfaces where the weld will take place.
~2 y Summary of the Invention According to one aspect of the invention there is provided an electrical resistance welding apparatus for making repeatable welds in lead storage batteries between battery lugs disposed on opposite sides of plastic partitions and pressed together to contact one another therethrough, comprising: (a) welding means for welding together a plurality of battery lugs, comprising: (i~
electrode means for contacting said lugs and conducting current thereto; and (ii) power means electrically con-nected to said electrode means for supplying a fixed amount of current to said electrode means for conduction to said lugs; (b) electrical resistance measuring means electrically connected across said power means for meas-uring the electrical resistance of said electrode means in contact with said lugs; and (c) an interface controller electrically connected to said resistance measuring means and to said welding means for determining said fixed amount of current and the time over which said current is to flow in response to said measurement of electrical resistance, and for communicating the same to said welding means, According to another aspect of the invention there is provided a method of making repeatable welds in lead storage batteries between battery lugs disposed on oppo-site sides of plastic partitions and pressed together to make contact therethrough, comprising the steps of: (a) providing welding means for applying current to said lugs;
~b) moving said welding means to contact said lugs; (c) measuring the electrical resistance of the lugs through a portion of said welding means in contact with said lugs; (d) determining the amount and time of current flow required to form said welds in response to said resist-ance measurement (e) controlling the amount and time of current flow delivered by said welding means to said lugs in response to said determination; and (f) withdrawing said welding means from said lugs.
Applicant's invention is based on the following equation:
H = (I ) (R) (T) (K) where H equals the heat needed for a weld; I2 equals the current squared; R equals the resistance of the parts involved in making the weld; T equals the time needed over which the current is applied to make the weld; and K
equals a proportionality factor relating H to the other factors, K relating to the heat dissipated into the atmosphere from the parts involved in making the weld.
A good weld can not be made without the proper amount of current being delivered within the right amount of time. If a certain amount of power is not present, then the heat can not be generated to melt the lead and create a fusion zone at the point where contact is made between the lugs. In order to be sure that the proper amount of current is delivered, the resistance of the electrode means in contact with the parts or lugs to be welded together must be known. This resistance can be made of several factors, for example, the resistance of the welding jaws to the electrodes tips; the resistance of the electrode tips to the welding surface on the lugs;
surface oxidation of the lead lugs; the composition of the various parts; the amount of antimony present; the pressure exerted on the lugs to squeeze them together, etc.
The only factors whlch are undecided once the heat H
D
and the factor K are either analytically or empirically determined are the factors I2, ~, and T. Applicant's system measures R and leaves only I2,T to be determined.
I ,T can be regulated by controlling the transformer output over a period of time. R is determined by the proper measurement of the resistance of the electrode means in contact with the lugs or parts to be welded together.
In the preferred embodiment, the measured resistance values are sent to an interface controller which uses this information to determine the correct amount of current and the time over which the current is to flow. This infor-mation is sent to the transformer controller which then applies a voltage to a transformer primary and a current begins to flow through the parts to be welded together.
In one embodiment of the invention, as the current is flowing during the making of the weld, it is measured by a current analyzer and the current value compared with the current value predicted by the interface controller.
If the measured current is different from the current determined by the interface controller, the control of the transformer through the transformer controller is adjusted by a command by the interface controller.
In the preferred embodiment, after the weld is com-plete, the resistance is remeasured if it is too high, the entire process is repeated. If after the second attempt at welding, the resistance is still too high, an indica-tion is made on the battery by a marking means, such as an inking system. This marking is sensed by a reject mechanism which~ in turn, rejects the battery from further processing.
~1115Q8 It is an advantage of the present invention, at least in preferred forms, that it can provide an electrical resistance welding apparatus for making repeatable welds in lead storage batteries between battery lugs disposed on opposite sides of plastic partitions by measuring the electrical resistance between the lugs that are to be welded together and by controlling the current which flows to make the weld in accordance with the resistance measurement.
It is another advantage of the present invention, at least in preferred forms, that it can provide an electrical resistance welding apparatus which marks those batteries with defective welds determined by the electrical resist-ance measurement.
It is another advantage of the present invention, at least in preferred forms, that it can provide an electrical resistance welding apparatus which automatically rejects batteries with defective welds.
Another advantage of the present invention, at least in preferred forms, is that it can provide an electrical resistance welding apparatus which measures the current flowing between the lugs to be welded together and which has a means of controlling the current delivered to the lugs to ~e welded together in accordance with the current measurement.
It is another advantage of the present invention, at least in preferred forms, that it can provide a method of making repeatable welds in lead storage battery lugs dis-posed on spposite sides of plastic partitions.
It is another advantage of the present invention, at least in preferred forms, that it can provide a method of - 5a -.~
)8 locating batteries with defective welds and rejecting said batteries.
This and other advantages of my invention will become apparent in the following description with reference to the accompanying drawings.
- 5b -. ~ .
Brief Description of the Drawings Fig. 1 is a schematic view of the electrical resistance welder of applicant's invention;
Fig. 2 is a cross-sectional view of the electrodes pressing together the lugc to be welded through a plastic partition, the lines contacting the electrodes representing the electrical connection of an electrical resistance measur ng means to the electrode means.
Detailed Description of the Drawings Although specific forms of the invention have been selected for illustration in the drawings, and the following description is drawn in specific terms for the purpose of describing these forms of the invention, this description is not intended to limit the scope of the invention which is defined in the appended claims.
Referring to the figures, in Fig. 1 a pair of welding jaws 10 and 12, shown in the standby position, are ready to move in the directions of arrows A and A' respectively to engage the battery lugs 14 and 16. The actual portions of the jaws 10 and 12 which engage the lugs are specially-designed protrusions or welding tips 18 and 20. When the welding tips 18 and 20 contact the lugs 14 and 16 and press them together, portions of the lugs are extruded into the opening 22 in the battery partition 24 which is shown disposed between the lugs 14 and 16. In the preferred embodiment shown in Fig. 1, the plastic partition 24 is an internal partition separating the cells o~
a battery; the lugs 14 and 16 are lead lugs y attached to the lead straps 26 and 28 which connect the individual terminal lugs of each of the battery plates within the adjacent cells. As in most modern batteries, the battery case and the partitions are made of a plastic material such as polypropylene. It will be noted that even though the preferred embodiment shows the weld being made between two internal battery lugs disposed on either side of a plastic cell partition, the same apparatus and method could be used to weld an external terminal throush a battery case wall to an internal lug within the battery.
Together, the welding jaws 10 and 12 with the electrode tip portions 18 and 20 comprise the electrode means desig-nated generally 13 which contact the lugs to be welded together and conduct current to the lugs to create the weld. The current is supplied to the electrode means from a power means designated generally 29 and together with the electrode means 13 they form the welding means portion of applicant's welder.
The preferred embodiment power means 29 comprises a current source for providing current to the electrode means such as the transformer designated generally 30 in Fig. 1, and a power control means such as transformer controller 31 in Fig. 1 for controlling the amount of current supplied to the electrode means. The schematic representation of the transformer in Fig. 1 shows that the preferred embodiment transformer is a magnetic core transformer with a primary 32 and secondary 34 shown with a rectified output by the diodes 36 and 38 connected to the ends of the secondary winding 34 and connected together at point 40. Point 40 is shown connected to welding jaw 12 by line 42, and line 44 is connected to welding jaw 10 and center tapped to secondary winding 34.
11115~8 This circuit provides a DC current source to the electrode means.
After the jaws 10 and 12 have contacted the lugs 14 and 16 respectively and extruded portions of the lugs into the aperture 22 to contact one another, but before power is delivered to the lugs for welding, an electrical resist-ance measuring means 46 in Fig. l measures the electrical resistance of the lugs through a portion of the electrode means in contact with the lugs. In Fig. 1, the resistance measuring means 46 is shown receiving inputs from line and arrow 48, and line and arrow 50 connected to points 52 and 54 on lines 42 and 44 respectively. This connection of the resistance measuring means at these points is schematic in nature since the choice of where the resistance is to be measured is critical in determining the actual resistance of the parts to be fused. For example, in Fig. 2, the welding jaws 10 and 12 are shown pressing against the lugs 14 and 16 to cause an extrusion in the aperture 22 and a contact between the lug extruded portions. The line and arrow 48 and the line and arrow 50 of Fig. l are shown as 48' and 50' in Fig. 2 and they are shown contacting the welding jaws at the electrode tip portions 18 and 20.
Hence, in Fig 1, the resistance to be measured will be made up of the following factors: the connection of the welding jaw bodies 10 and 12 to the electrode tip por-tions 18 and 20; the connection between the welding tips 18 and 20 to the lugs 14 and 16; and the contact between the lugs. Fig. 2 shows more clearly how the lugs are ex-truded into aperture 22 where the extruded portions 56 and 58 are shown contacting one another. In an alternate embodiment of applicant's invention where the secondary output of the transformer is S~)~
not rectified, an alternating current is delivered to the lugs and the resistance of the electrode means in contact with the lugs can be made through the transformer.
Referring now to Fig. 1, once the resistance has been measured, it is transmitted by the measuring means to the interface controller 60 by the line and arrow 62. The inter-face controller takes this resistance information and from it determines the amount of current and time over which the current is to flow as determined by the aforementioned equation H = (I2) ~R) (T) (K). This can be accomplished, for example, by having the interface controller 60 obtain the proper current and time from a look-up table which is a memory or storage of different relationships between the resistance that is measured and the proper c.urrent and time that is required to provide a given heat as pre-determined and stored in the interface controller 60. Alternatively, the interface controller could be a microprocessor which is capable of analytically determining the current from the measured resistance and use of the heat e~uation above. The interface controller 60 then sends this information by way of a signal in line and arrow 64 to the welding means such as the transformer controller 31 of the power means which in turn activates the transformer of the power means to deliver a fixed amount of current during a fixed time period to said electrode means. The information sent from the transformer controller 31 to the transformer 30 is sent by line and arrow 66. At the same time, the trans-former controller 31 transmits the information back to the interface controller on line and arrow 68 so th~t it can be compared for accuracy.
~1~1508 Hence, applicant's preferred embodiment measures the resistance of the contact between the lugs contacting one another through the plastic partition wall and, from this information, determines the proper amount of current and duration over which this current should flow in order to provide a thorough and repeatable weld. The method by which this is accomplished is as follows: the battery with the lug surrounding the plastic partition is brought into place between the welding jaws; the welding jaws are then moved in the direction shown by arrow A and A' in Fig. 1 until they contact the lug surfaces upon which pressure is applied and portions of the lug surfaces are extruded into the aperture 22 to contact one another; the resistance of the lugs is then measured through a portion of the welding means in contact with said lugs by the re-sistance measuring means and that information is then sent to the interface controller; the interface controller uses the resistance measurement to determine the proper amount of current and the time which that current is to flow, and sends this information to the transformer controller; the transformer controller controls the amount of current out-put from the transformer and the period of time of the output; the transformer receives the command from the transformer controller and outputs the proper amount of current over a given amount of time; and this current then flows through the electrode means, that is, through the welding jaws, electrode tips and the lug contacts heating the lugs and fusing the lead in the aperture 22. The welding means or welding jaws are then withdrawn to free 3~ the battery. The current delivered to the lugs can ~e either direct or alternating.
In order to insure that the weld is a proper one, f~
~1115Q8 applicant's invention provides for a second measurement of the resistance after the welding process is complete. If a good fusion has taken place, the resistance of the lug connection will be much lower than that of the pre-weld contact, e.g., less than 5 micro-ohms. If the resistance is not within a desirable range, the new value of the resistance can be used to begin the process over again.
If for some reason a good weld cannot be attained as determined by the resistance measurement, then applicant has provided a means in the apparatus for marking and rejecting defective weld batteries. Referring to Fig. 1, marking means 7~ marks those batteries where weld resist-ance values are too high. For example, when the resistance measuring means is told by the interface controller 60 via line and arrow 72 that the final resistance measurement of the attempted weld is too high, then the marking means such as ink system 70 in response to command from the measuring means 46 via line and arrow 75 deposits a few drops of ink in the defective battery in a prominent location on the battery. Of course, any marking means which could designate a battery with a bad weld could be used and the applicant is showing here the preferred embodiment ink system 70. The battery then proceeds down the assembly line where the reject mechanism 77 having been notified in advance of the faulty weld by the resistance measuring means 46 via line and arrow 74 rejects the battery ~rom the conveying system or assembly line so that further processing on that battery would not take place. In this way, batteries that had welds which were not repeatable and up to a certain quality level, for example, less than 5 micro-ohms, would not proceed further and find their way into the marketplace.
B
~11S08 Should the interface controller receive a resistance measurement at any time which did not fall within the look-up table or other means for determining the amount of current and time required to create a proper weld, the interface controller 60 is equipped to signal the resistance measuring means 46 to make another measure-ment. This is indicated by the line and arrow 72.
~ ence, a method is disclosed by applicant whereby batteries with defective welds are detected through resistance measurements, marked as defective and thereby rejected upon detecting the marking.
It may be desirable in the apparatus and method to have a means of correcting the current flowing to the lugs during the actual welding process. Current analyzer 76 in Fig. 1 measures the current flowing through the lugs during the welding process. It is shown electrically connected in series with welding jaw lO at points 54 and 78 connected by a shunt 44 and the information is received via line and arrow 80 and line and arrow 82. When the current has been measured by the current analyzer 76, the information is sent via line and arrow 100 to the interface controller 60 where the measured value of the current is compared with the value of the current determined by the interface controller 60 to be the optimum for creating the weld from 'he value of the resistance as measured by the resistance measuring means 46. The interface controller 60 has the ability to control the transformer controller 31 so that a real time change in the current flowing through the weld can be made by the interface controller 60 of the current, as measured by the current analyzer 76, does not match the current as deter-mined by the interface controller 60. This leads to an even finer control of the process of making the weld.
- 12 - t 1:1115~8 The interface controller receives information from various sources such as the resistance measuring means 46, the transformer controller 31 and the current analyzer 76. It uses the information that it receives to control the welding opera-tion of the entire welding apparatus. For example, upon receipt of information from the resistance measuring instrument 46 as to the resistance of the preweld lug contact, the interface controller selects the appropriate current that must be deliver-ed in a given period of time in order to create enough heat to fuse the lead together in the aperture 22. This information is sent to the transformer controller in such a way as to allow the transformer controller to energize the transformer which ulti-mately provides the current to the lug region. If there is something wrong with the initial or subsequent resistance measurements such that they are not within an acceptable range of resistance measurements, the interface controller can through line and arrow 72, signify the resistance measurement to recycle or to reject. Similarly, after the transformer controller has signaled the transformer to energize, it can tell the inter-face controller via line and arrow 68, what information it provided to the transformer which the interface controller then compares with its own information to determine whether or not the transformer controller is acting correctly. If it is not, it can recycle the process. Also, should the current analyzer 76 provide current information to the interface controller which does not agree with the information determined by the interface controller based on a resistance measurement, the interface controller can e;ther signal the transformer to increase or decrease the power from the transformer in order to bring it in agreement with the value being measured by the current analyzer, or it can ~lllS~)8 stop and recycle the process. Finally, the interface con-troller is capable of providing a signal to the resistance measuring means via line 72 that the final resistance mea-surement in the process was inadequate and that a battery with a defective weld existed. The interface controller signals the resistance measuring means 46 to trigger the ink system 70 to so mark the battery and at the same time it would tell the resistance measuring means to signal the reject mechanism to ~e ready to sense a battery with a defective weld marking so as to reject that battery from further processing. Hence, the interface controller acts as a control for the entire welding apparatus in its func-tion of interfacing with the various instruments and control mechanisms in the apparatus. This fine control of the welding operation provides a means of insuring repeatable welds and high quality control.
It will be understood that various changes in the details, materials and arrangement of parts which have been herein described and illustrated in order to explain the nature of this invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the following claims.
B
Claims (16)
1. An electrical resistance welding apparatus for making repeatable welds in lead storage batteries between battery lugs disposed on opposite sides of plastic partitions and pressed together to contact one another therethrough, comprising:
(a) welding means for welding together a plurality of battery lugs, comprising:
(i) electrode means for contacting said lugs and conducting current thereto; and (ii) power means electrically connected to said electrode means for supplying a fixed amount of current to said electrode means for conduction to said lugs;
(b) electrical resistance measuring means electrically connected across said power means for measuring the electrical resistance of said electrode means in contact with said lugs; and (c) an interface controller electrically connected to said resistance measuring means and to said welding means for determining said fixed amount of current and the time over which said current is to flow in response to said measurement of electrical resistance, and for commun-icating the same to said welding means.
(a) welding means for welding together a plurality of battery lugs, comprising:
(i) electrode means for contacting said lugs and conducting current thereto; and (ii) power means electrically connected to said electrode means for supplying a fixed amount of current to said electrode means for conduction to said lugs;
(b) electrical resistance measuring means electrically connected across said power means for measuring the electrical resistance of said electrode means in contact with said lugs; and (c) an interface controller electrically connected to said resistance measuring means and to said welding means for determining said fixed amount of current and the time over which said current is to flow in response to said measurement of electrical resistance, and for commun-icating the same to said welding means.
2. The invention of Claim 1 wherein said power means comprises a current source electrically connected to said electrode means; and a power control means electrically connected to said current source for controlling the amount of current supplied to said electrode means from said current source in response to said communication from said interface controller.
3. The invention of Claim 2 wherein said current source is a transformer for supplying alternating current to said electrode means.
4. The invention of Claim 2 wherein said current source is a transformer having a rectified secondary output for supplying direct current to said electrode means.
5. The invention of Claim 4 wherein said electrode means comprises at least two welding jaws, each jaw having an electrode tip portion, said tip portion contacting said lugs, said electrical resistance measuring means making electrical contact with said electrode means at said electrode tip portions.
6. The invention of Claim 1 wherein said apparatus fur-ther comprises a marking means for marking batteries with defective welds upon command from said resistance measuring means, said marking means electrically connected to said resistance measuring means.
7. The invention of Claim 6 wherein said apparatus comprises a reject mechanism for sensing said markings, said reject mechanism discarding said battery with defective welds from further processing in response to said sensing, said reject mechanism electrically connected to said resistance measuring means.
8. The invention of Claim 7 wherein said marking means is an ink dispenser for depositing ink on said batteries with defective welds.
9. An electrical resistance welding apparatus for making repeatable welds in lead storage batteries between battery lugs disposed on opposite sides of plastic partitions, comprising:
(a) welding means for welding together a plurality of battery lugs, comprising:
(i) electrode means for contacting said lugs and conducting current thereto; and (ii) power means for supplying a fixed amount of current to said electrode means for conduction to said lugs, said power means electrically connected to said electrode means;
(b) electrical resistance measuring means electrically connected across said power means for measuring the electrical resistance of said electrode means in contact with said lugs;
(c) current measuring means electrically connected between said power means and said electrode means for measuring the flow of current through said electrode means and said lugs; and (d) an interface controller electrically connected to said welding means, said resistance measuring means and said current measuring means, for determining said fixed amount of current and the time over which said current is to flow in response to said measurement of said electrical resistance and communicating the same to said welding means, and for comparing said determination with the measurement of said flow of current.
(a) welding means for welding together a plurality of battery lugs, comprising:
(i) electrode means for contacting said lugs and conducting current thereto; and (ii) power means for supplying a fixed amount of current to said electrode means for conduction to said lugs, said power means electrically connected to said electrode means;
(b) electrical resistance measuring means electrically connected across said power means for measuring the electrical resistance of said electrode means in contact with said lugs;
(c) current measuring means electrically connected between said power means and said electrode means for measuring the flow of current through said electrode means and said lugs; and (d) an interface controller electrically connected to said welding means, said resistance measuring means and said current measuring means, for determining said fixed amount of current and the time over which said current is to flow in response to said measurement of said electrical resistance and communicating the same to said welding means, and for comparing said determination with the measurement of said flow of current.
10. A method of making repeatable welds in lead storage batteries between battery lugs disposed on opposite sides of plastic partitions and pressed together to make contact therethrough, comprising the steps of:
(a) providing welding means for applying current to said lugs;
(b) moving said welding means to contact said lugs;
(c) measuring the electrical resistance of the lugs through a portion of said welding means in contact with said lugs;
(d) determining the amount and time of current flow required to form said welds in response to said resistance measurement;
(e) controlling the amount and time of current flow deliv-ered by said welding means to said lugs in response to said determination; and (f) withdrawing said welding means from said lugs.
(a) providing welding means for applying current to said lugs;
(b) moving said welding means to contact said lugs;
(c) measuring the electrical resistance of the lugs through a portion of said welding means in contact with said lugs;
(d) determining the amount and time of current flow required to form said welds in response to said resistance measurement;
(e) controlling the amount and time of current flow deliv-ered by said welding means to said lugs in response to said determination; and (f) withdrawing said welding means from said lugs.
11. A method of Claim 10 wherein the step (c) is accom-plished using alternating current.
12. A method of Claim 10 wherein the step (c) is repeated between steps (e) and (f).
13. A method of Claim 12 wherein steps (d) and (e) are repeated before step (f) when the electrical resistance of said welds as determined by the repetition of step (c) is greater than a preselected value.
14. A method of Claim 13 wherein said preselected value is 5 micro-ohms.
15. A method of Claim 12 wherein the following steps are added after step (f):
(g) marking said battery for rejection when said electrical resistance is greater than a preselected value; and (h) rejecting said battery marked by step (g).
(g) marking said battery for rejection when said electrical resistance is greater than a preselected value; and (h) rejecting said battery marked by step (g).
16. A method of making repeatable welds in lead storage batteries between battery lugs disposed on opposite sides of plastic partitions and pressed together to make contact therethrough, comprising the steps of:
(a) providing welding means for applying current to said lugs;
(b) moving said welding means to contact said lugs;
(c) measuring the electrical resistance of the lugs through a portion of said welding means in contact with said lugs;
(d) determining the amount and time of current flow required to form said welds in response to said resistance measurement;
(e) providing said current flow to said lugs in response to said determination of step (d);
(f) measuring the amount of current flowing through said lugs during the welding process;
(g) comparing the measurement of step (f) with the deter-mination of the amount of current from step (d);
(h) varying the amount and time of current flow through said lugs to minimize any differences detected in step (g);
and (i) withdrawing said welding means from said lugs.
(a) providing welding means for applying current to said lugs;
(b) moving said welding means to contact said lugs;
(c) measuring the electrical resistance of the lugs through a portion of said welding means in contact with said lugs;
(d) determining the amount and time of current flow required to form said welds in response to said resistance measurement;
(e) providing said current flow to said lugs in response to said determination of step (d);
(f) measuring the amount of current flowing through said lugs during the welding process;
(g) comparing the measurement of step (f) with the deter-mination of the amount of current from step (d);
(h) varying the amount and time of current flow through said lugs to minimize any differences detected in step (g);
and (i) withdrawing said welding means from said lugs.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US81043477A | 1977-06-27 | 1977-06-27 | |
| US810,434 | 1977-06-27 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1111508A true CA1111508A (en) | 1981-10-27 |
Family
ID=25203847
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA305,400A Expired CA1111508A (en) | 1977-06-27 | 1978-06-14 | Apparatus and method for making electrical resistance welds in a storage battery |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA1111508A (en) |
| GB (1) | GB1600319A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3504159A1 (en) * | 1985-02-07 | 1986-08-07 | Accumulatorenfabrik Sonnenschein GmbH, 6470 Büdingen | CONTROL CIRCUIT FOR THE POWER OF A WELDING TRANSFORMER |
| US4672167A (en) * | 1985-06-17 | 1987-06-09 | General Battery Corporation | Method and apparatus for welding metallic parts |
-
1978
- 1978-05-30 GB GB2409778A patent/GB1600319A/en not_active Expired
- 1978-06-14 CA CA305,400A patent/CA1111508A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB1600319A (en) | 1981-10-14 |
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