ENERGY WELDING DEVICE AND METHOD

Abstract

The present disclosure relates to a novel system and methods enabling welding of thermoplastic parts by computation and measured delivery of heat energy required as opposed to computation of power over time without consideration for heat build-up in the delivery system. One application is in plastic staking.

Claims

1. A computer-controlled welding system for precision energy management, comprising: a power source configured to supply electrical energy; a voltage sensor connected to the power source for measuring voltage supplied to a welding circuit; a current sensor connected in the welding circuit for measuring current flowing through the welding circuit; a relay operatively connected to the power source for controlling the supply of electrical energy; a transformer for adjusting the voltage supplied by the power source to the welding circuit; a heat applicator including leads connected to the welding circuit and a tip for applying heat to materials to be welded; a controller configured to receive inputs from the voltage sensor and the current sensor, and to control the relay based on the received inputs; and a non-transitory computer-readable medium storing instructions that, when executed by the controller, perform operations comprising: calculating an optimal energy output based on the inputs from the voltage and current sensors; adjusting the supply of electrical energy through the relay based on the calculated optimal energy output; and monitoring the welding process to adjust the energy output in real-time for precision welding.

2. The system of claim 1, further comprising: a power sensor operatively connected to the controller, configured to measure the total power consumption of the welding system, wherein the stored instructions further include operations for adjusting the welding process based on the measured total power consumption.

3. A computer-implemented method for precision welding by computation of energy, comprising: placing materials to be welded in a predetermined position using a controller; aligning the heat applicator with the materials to be welded under control of the controller; making contact between the heat applicator tip and the materials to be welded under control of the controller; energizing the welding circuit to apply a calculated amount of energy to the materials based on inputs from voltage and current sensors, as controlled by the controller; retracting the heat applicator from the materials after the application of energy, as controlled by the controller; and removing the welded materials from the predetermined position, as controlled by the controller.

4. The method of claim 3, further comprising: measuring, by the controller, the effectiveness of the weld after the energize step through feedback from at least one of a voltage sensor, a current sensor, and a power sensor; deciding, by the controller, whether the measured effectiveness meets predetermined criteria; directing, by the controller, a return to the energize step for additional energy application if the predetermined criteria are not met, or continuation to the retract step if the criteria are met.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0017] For a fuller understanding of the nature and advantages of the present method and process, reference should be had to the following detailed description taken in connection with the accompanying drawings, in which:

[0018] FIG. 1 depicts the system.

[0019] FIG. 2 shows an open loop method.

[0020] FIG. 3 shows a closed loop method.

[0021] The drawings are described in greater detail below.

DETAILED DESCRIPTION OF THE DRAWINGS

[0022] Consider a first part and a second part, both being thermoplastics, to be joined. For discussion, the first part has additional thermal plastic material manufactured at the place where the parts are to be joined. Alternatively, the second part, or both parts could have such additional, manufactured material. A fixture is used to hold the first and second parts in place as heat is applied.

[0023] It is well known that, in an electrical circuit, that power is generally voltage times current. If the voltage is sinusoidal, then average power is the product of the RMS values for voltage and current. Energy, then, is the mathematical integration of power over time. In a computer-controlled system with appropriate sensors, voltage and current can be regulated over time to deliver a desired amount of energy to a load. Further, as contemplated here, electrical energy is converted to heat energy to accomplish the desired welding task.

[0024] FIG. 1 shows the one embodiment of system 100. comprising a welding circuit. Electrical energy 118 is produced in a power source 106. In this embodiment, the power source 106 would typically be 110 volt or 220 volt (VAC) providing alternating current. Voltage sensor 112 and current sensor 114 are arranged to provide voltage and current information used to compute energy to be delivered. Although FIG. 1 shows current sensor 114 in series, other topologies, such as measuring voltage across a shunt resistor, may be used to provide current information 108. A relay 110, typically a solid state or electromechanical relay, controls current delivered to a transformer 108, primary side. When relay 110 is on, electrical energy 118 is induced through transformer 108 from primary side to its secondary side. Transformer 108 is typically step-down, reducing voltage at its secondary side to 5 VAC. That electrical energy 118 is then delivered through leads 120 to a tip 122. The tip 122 creates a short circuit, which transforms electrical energy 118 to heat energy 119. Controller 102, as instructed by its program 104 and corresponding instructions 502, receives voltage information 506 from voltage sensor 112 and current information 508 from current sensor 144, and computes in real time the flow of electrical energy 118. Controller 102, via relay control 510, directs relay 110 to be on or off, and thus manages the flow of electrical energy through transformer 108. After delivery of the required heat energy 119, relay 510 would be set to off. Controller 102 may also manage the electrical output of power source 106 via waveform control 504. As such, power source 106 waveform may be manipulated increase or decrease effective electrical energy 118. Deep leads 120 and tip 122 comprise a heat applicator 140 which is used to deliver heat energy 119 to parts 130 and 134 to be joined. Bond material 132 is provided on thermoplastic parts 130 or part 134 or both, which when provided with heat energy sufficiently will cause parts 130 and 134 to be joined.

[0025] In other embodiments, waveform control 504 from controller 102 may be directed on the secondary side of transformer 108, as opposed to the primary side as shown in FIG. 1.

[0026] In other embodiments, voltage of power source 106 may be fixed. In such case, voltage sensor 112 may not be required, and other means may be used to control voltage and current waveforms to deliver a desired amount of electric energy 118.

[0027] In an alternative embodiment, energy sensor 142 provides energy information 512 to controller 102 on the amount of energy in the heat applicator 140, so that controller 102 can decide how much energy 119, if any, must still be delivered in order to join parts 130 and 134. Energy sensor 142 may provide temperature and heat information which the controller 102 would use to compute power. Energy 119, of course, is delivered as heat energy.

[0028] FIG. 2 shows an open loop method 200, as directed by controller 102 and its program 104. In placement step 202, the first part 130, with the additional bond material 132, is placed into the fixture and held securely. In alignment step 204, the second part 134 is aligned with the first part 130 as desired. In contact step 206, the heat applicator 140 is applied appropriately to parts 130 and 134 at the place where they are joined relative to bond material 132. A measured amount of heat energy 119 (computed from electrical energy 118) is then applied in the energize step 208, based on the particular properties of the parts 130 and 134, and bond material 132. After the appropriate amount of energy 119 is delivered, the heat applicator 140 is withdrawn in the retract step 210, and the joined parts are taken as one from the fixture in the remove step 212.

[0029] FIG. 3 shows closed loop method 300, as directed by controller 102 and its program 104. As in FIG. 2, in placement step 202, the first part 130, with bond material 132, is placed into the fixture and held securely. In the alignment step 204, the second part 134 is aligned with the first part 130 as desired. In the contact step 206, the heat applicator 140 is applied appropriately to the parts 130 and 134 and bond material 132 at the place where they are joined. Here, though, in measure step 308, energy in the heat applicator 140 is measured via energy sensor 142 to determine incremental amount of heat energy needed to accomplish the weld based on the particular properties of the parts 130 and 134, and the bond material 132. From that, incremental amounts of electrical energy 118 needed to produce heat energy 119 are determined. The incremental measured amounts of heat energy are then applied a loop comprising in the energize step 308 and the decision step 309, until all required energy has been delivered. In an alternative embodiment, heat energy already in heat applicator 140 will be considered in the determination of how much additional energy is needed in step 308. After the appropriate amount of energy is delivered, the heat applicator 140 is withdrawn in the retract 210 step, and the joined parts are taken as one from the fixture in the remove 212 step.

[0030] While the apparatus, system, and method have been described with reference to various embodiments, those skilled in the art will understand that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope and essence of the disclosure. In addition, many modifications may be made to adapt a particular situation or material in accordance with the teachings of the disclosure without departing from the essential scope thereof. Therefore, it is intended that the disclosure not be limited to the particular embodiments disclosed, but that the disclosure will include all embodiments falling within the scope of the appended claims. Also, any and all citations referred to herein are expressly incorporated herein by reference.