Patent ID: 12260990

DETAILED DESCRIPTION

Various methods, apparatuses, devices, and systems are described herein which relate to drawn arc fastener welding. More specifically, the embodiments described herein relate to portable drawn arc fastener welding systems. The apparatuses, devices, and systems disclosed herein can deliver full strength stud welds for structural applications and have a form factor that allows a single user/operator to easily use and move.

Energy storage based, drawn arc stud welders have historically been powered from AC power outlets, typically 120 VAC/60 Hz in the United States, or 220 VAC/50 Hz in Europe. Because energy storage based, drawn-arc welders require substantial charging current to charge the capacitor bank rapidly between welds, traditional welders typically require 10-20 amp capacity from a 120 VAC line, or 5-10 amp capacity from a 220 VAC line. This requirement is generally met by having a high capacity line cord for power, usually a 16 AWG to 14 AWG, 3-conductor cord. This cord, when extended to allow the welding tool to be used at a distance from the power outlet, adds substantial weight, restricted movement, safety concerns (shock/tripping/arc flash) and limited portability. The portable systems described herein eliminates the need for the line cord, while also preserving the benefit of being very light weight. Additionally, the energy storage devices of the present disclosure allow the devices and systems to display significantly improve capabilities over those devices and systems of the prior art. In particular, the energy density is significantly higher (i.e., about 40× that of traditional capacitors).

The singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.

As used in the specification and in the claims, the term “comprising” may include the embodiments “consisting of” and “consisting essentially of.” The terms “comprise(s),” “include(s)”, “having,” “has,” “can,” “contain(s),” and variants thereof as used herein, are intended to be open-ended transitional phrases, terms, or words that require the presence of the named components and permit the presence of others.

Numerical values in the specification and claims of this application should be understood to include numerical values which are the same when reduced to the same number of significant figures and numerical values which differ from the stated value by less than the experimental error of conventional measurement techniques.

All ranges disclosed herein are inclusive of the recited endpoint and independently combinable (for example, the range “from 2 to 10” is inclusive of the endpoints, 2 and 10, and all the intermediate values).

The term “about” can be used to include any numerical value that can vary without changing the basic function of that value. When used with a range, “about” also discloses the range defined by the absolute values of the two endpoints, e.g., “about 2 to about 4” also discloses the range “from 2 to 4”. The term “about” may refer to plus or minus 10% of the indicated number.

As used herein, the term “drawn arc stud welding operation” refers to and means the process of welding a single stud fastener to a parent metal using a drawn arc welding process, which generally includes the steps of energizing a pilot arc current, lifting the weld stud off a workpiece and drawing the pilot arc, energizing a weld using a welding current for a specified amount of time, and plunging the weld stud into the workpiece.

As used herein, the terms “operatively connected” and “electrically connected” refer to and mean a component is connected to another component in such a manner so as to facilitate the transmission of electrical signals and/or electrical current.

Referring now to the drawings,FIG.1illustrates a block diagram of a drawn arc fastener welding system100in accordance with one aspect of the present disclosure. The system includes at least a charging circuit105, an energy storage device110, and a discharge circuit115. In further embodiments, the system100can also include an external power supply120, a drawn arc stud welding tool125, and/or a control system130.

The charging circuit105can be operatively (e.g., electrically) connected to the energy storage device110and an external power supply120. The energy storage device110can be operatively (e.g., electrically) connected to the charging circuit105and the discharge circuit115. The discharge circuit can be operatively (e.g., electrically) connected to the energy storage device110and the welding tool125. In particular embodiments, the control system130is operatively connected to one or more of: the charging circuit105; the energy storage device110; the discharge circuit115; the power supply120; and/or the welding tool125.

The external power supply120can supply power to the system100by, for example, supplying a current i1135to at least the charging circuit105. The charging circuit105may be configured to receive the current i1135and generate a charging circuit i2140, which is communicated to the energy storage device110. In other words, the charging circuit105regulates the charging of the energy storage device110by generating and providing a controlled current i2140to the energy storage device110.

The energy storage device110can be configured to receive the charging current i2140and store at least a first amount of energy. The energy stored by the energy storage device110can be used to support one or more drawn arc stud welding operations, including a plurality of drawn arc stud welding operations.

The discharge circuit115can be configured to receive an output current i3145from the energy storage device110and generate a discharge current i4150. When operatively connected to a welding tool125, such as a stud fastener welding tool, the discharge circuit115communicates/delivers the discharge current i4150to the welding tool125for a first time duration. That is, the discharge circuit115delivers a discharge current i4150to the welding tool125for the requisite amount of time in order to: (i) generate an arc155between the fastener (not shown) and the parent metal160; and (ii) complete a welding operation.

As mentioned above, the system100can include a control system130operatively connected to one or more of: the charging circuit105; the energy storage device110; the discharge circuit115; the power supply120; and/or the welding tool125.

In particular embodiments, the control system130includes at least one processor; a memory configured to store instructions to be executed by the at least one processor; and a user interface configured to enable multiple user-selectable modes of operation for the drawn arc fastener welding system100. For example, the control system130may be configured to: (i) monitor voltages in the energy storage device110; (ii) protect the energy storage device110from overvoltage by controlling the charging circuit105; (iii) control and coordinate all power supplies as the welding operation requires; (iv) monitor temperature within the charging circuit105; and/or (v) monitor the health of the external power supply120.

The memory of the control system130may represent any type of non-transitory computer readable medium such as random access memory (RAM), read only memory (ROM), magnetic disk or tape, optical disk, flash memory, or holographic memory. In one embodiment, the memory comprises a combination of random access memory and read only memory. In some embodiments, the processor and memory may be combined in a single chip. The memory of the control system130stores instructions for performing at least the steps described above, as well as the processed data, as necessary, such as any user-defined settings.

The digital processor of the control system130can be variously embodied, such as by a single-core processor, a dual-core processor (or more generally by a multiple-core processor), a digital processor and cooperating math coprocessor, a digital controller, or the like.

The term “instructions” as used herein is intended to encompass any collection or set of instructions executable by a computer or other digital system so as to configure the computer or other digital system to perform the task that is the intent of the software. Such instructions can be stored in storage medium such as RAM, a hard disk, optical disk, or so forth, and is also intended to encompass so-called “firmware” that is software stored on a ROM or so forth. Such software may be organized in various ways, and may include software components organized as libraries, Internet-based programs stored on a remote server or so forth, source code, interpretive code, object code, directly executable code, and so forth. It is contemplated that the software may invoke system-level code or calls to other software residing on a server or other location to perform certain functions.

The software instructions of the control system130may include various components for implementing parts of the method. For example, the instructions of the control system130include components configured to: (i) monitor voltages in the energy storage device110; (ii) protect the energy storage device110from overvoltage by controlling the charging circuit105; (iii) control and coordinate all power supplies as the welding operation requires; (iv) monitor temperature within the charging circuit105; (v) monitor the health of the external power supply120; and/or (vi) control a variable speed cooling device (e.g., cooling device890shown inFIG.8).

With reference toFIG.2andFIG.8, schematics of a drawn arc stud welding system200,800are illustrated in accordance with a second and third embodiment of the present disclosure. Here, the drawn arc stud welding system200,800includes: (i) a charging circuit205,805; (ii) an energy storage device210,810; (iii) a discharge circuit215; (iv) a pilot arc circuit265; (v) a constant current supply circuit270; and (vi) an internal discharge circuit275. As illustrated, the system200can also include an external power supply220, such as a battery pack, a control system230, and/or a cooling apparatus, such as a variable speed fan890. The system200may further include a welding tool225, such as a stud gun, having a positive terminal280and a negative terminal285.

As seen inFIGS.2and8, the charging circuit205,805can be operatively connected to the external power supply220and the energy storage device210,810; the energy storage device210can be operatively connected to the charging circuit205,805and the discharge circuit215; and the discharge circuit215can be operatively connected to the energy storage device210,810and the drawn arc stud welding tool225, for example, via the negative terminal285. Further, the pilot arc circuit265can be operatively connected to the charging circuit205,805. The constant current supply circuit270can be operatively connected to the energy storage device210,810and the weld tool225(e.g., via terminal285). And the internal discharge circuit275can be operatively connected to the energy storage device210,810and the weld tool225(e.g., via terminal285).

In particular embodiments, the system200can include a control system230, which may be operatively connected to one or more of: the charging circuit205; the energy storage device210; the discharge circuit215; the power supply220; the pilot arc circuit265; the constant current supply circuit270; the weld tool225; and/or a variable speed cooling device (e.g., cooling device890shown inFIG.8).

The discharge circuit215can be, for example, a chopper constant-current discharge circuit configured to deliver up to about 2000 ADC for a period of time (i.e., during a welding operation). The discharge circuit215can include at least a transistor to regulate a constant discharge current, which may be operatively connected to the control system230.

In certain embodiments, the power supply220may be a battery pack (i.e., a plurality of cells), such as a lithium-ion battery pack. In some embodiments, the power supply220may be a lithium nickel manganese cobalt oxide (LiNiMnCoO2) battery pack. The power supply220may have a voltage of at least 50V, or about 52V. The power supply220may have a bus voltage of about 48 VDC. In specific embodiments, the power supply220should be capable of provided the energy storage device210with between about 20 and about 30 amps between weld operations. In specific embodiments, the power supply220is a 20-30 A at 52V power supply. In further specific embodiments, the power supply220is not a LiFePO4power supply.

The charging circuit205,805may be a synchronous constant-current constant-voltage buck switching supply configured to regulate the charging of the energy storage device210,810. In some embodiments, the charging circuit205,805has a switching frequency of at least 150 kHz, or about 150 kHz. As shown inFIG.3, the charging circuit205can comprise a transistor302, two rectifier diodes304,306, and an inductor308. In further embodiments, such as those illustrated inFIG.9, the charging circuit805can comprise two transistors902,904, a rectifier diode906, a thermal sensor909, and an inductor908.

In particular embodiments, one or more temperature sensors309of the charging circuit205are operatively connected to the control system230. These temperature sensors909can be used by the control system230to monitor the temperature of the charging circuit805and control the variable speed fans890.

Turning toFIGS.4and10, the energy storage device210,810may comprise a plurality of capacitors402, including at least about 10 capacitors402, or between about 10 and about 20 capacitors, or about 16 capacitors402. Each of the capacitors402may be operatively connected in series. In certain embodiments, the capacitors402may be polarized capacitors402and/or low equivalent series resistance (“ESR”) capacitors402. In further embodiments, each of these capacitors402may be an ultracapacitor, such as a 3.0V ultracapacitor cell. As described above, these capacitors402may be configured to store sufficient energy to support at least one drawn arc stud welding operation. For example, the energy storage device210,810may store at least about 100 KJ of energy, or at least about 200 kJ, or between about 100 kJ to about 300 KJ, or about 200 kJ, or about 215 kJ. Accordingly, the energy storage devices210,810of the present disclosure are capable of providing a high-power pulse needed for a stud weld operation.

In some embodiments, the energy storage device210may further comprise one or more temperature sensors404operatively connected to the control system230, as shown inFIG.4. These temperature sensors404may be used by the control system230to monitor the temperature of ultracapacitor cells402. In further embodiments, each ultracapacitor402may include a voltage limiter circuit1003as shown inFIG.10. These voltage limit circuits1003can be used to monitor and limit voltage by draining energy as required.

Turning toFIG.5, the pilot arc circuit265may be a chopper constant-current switching supply configured to deliver a pilot arc via the weld tool225,285. In some embodiments, the pilot arc circuit265has a switching frequency of at least 150 kHz, or about 150 KHz. As seen inFIG.5, the pilot arc circuit265may include a transistor502, one or more rectifier diodes504,506, and an inductor508. Further, the pilot arc circuit265may be operatively connected to the weld tool225, for example, via the negative terminal285of the weld tool225.

In certain embodiments, the system200,800includes an internal discharge circuit275, which can be configured to dissipate energy from the ultracapacitors when service of the system200,800is required.

As shown inFIG.6, the system200,800can include an internal discharge circuit275configured to reduce the energy stored in the energy storage device210,810to zero or about zero. The internal discharge circuit275may include a push-button switch602, one or more resistors604,606, and a rectifier diode608. In particular embodiments, the rectifier608can be a silicon-controlled rectifier (“SCR”), which blocks until the “gate” is fired, after which it will conduct current in the forward direction like a standard diode until current reaches a low threshold value, after which it will block again.

Turning toFIG.7, the system200,800can include a separate constant current supply circuit270. The constant current supply circuit270may be configured to separately provide energy to the weld tool225. For example, in particular embodiments, the constant current supply circuit270may be configured to drive the operation of a solenoid (not shown) of the weld tool225. The solenoid of the weld tool225is used to control the position of the stud/fastener that is to be welded to the parent metal. In some embodiments, the constant current supply circuit270may be a buck-boost supply configured to charge a separate capacitor to about 100 VDC for driving the weld tool solenoid. As illustrated inFIG.7, the constant current supply circuit270can include a transistor702, a rectifier diode704, a capacitor706, and an inductor708.

It will be appreciated that variants of the above-disclosed and other features and functions, or alternatives thereof, may be combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.

To aid the Patent Office and any readers of this application and any resulting patent in interpreting the claims appended hereto, applicants do not intend any of the appended claims or claim elements to invoke 35 U.S.C. 112(f) unless the words “means for” or “step for” are explicitly used in the particular claim.