JPH03154670A - Heat sealing system for thermosetting material - Google Patents

Abstract

PURPOSE: To eliminate the internal temp. difference in a material and to completely heat the entire volume by providing a material heater with a hollow enclosure, coiled tube, electric heater, thermosensitive device and electronic controller. CONSTITUTION: This welding system is provided with a device for supplying a flowable thermosetting material, such as epoxy, under pressure, a device 32 for heating the material to a higher temp. than the ambient, a device for welding the material to a base material at a high temp. and conduits 30, 34 for supplying the material from the supplying device to the device 32 and further to the welding device. The device 32 is provided with the hollow enclosure 40 having an inner volume part, the spiral coiled conduit 54 having first and second tube terminal parts 58, 60 which are suspended in the enclosure 40 and are connected to the conduits 30, 34, the electric heater 66 disposed within the enclosure 40 for heating the volume part, the thermosensitive device 72 far sending an electronic signal as a function of temp. and the electronic controller 78 having the device responding with the electric signal so as to add electric power by a selection system on the electric heater 66 for holding the temp. in the volume at the elevated temp.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a system for adding or welding thermosetting materials such as structural epoxies, and more particularly, to systems for adding or welding thermosetting materials such as structural epoxies, and in particular for bringing the materials to a predetermined temperature above or below room temperature prior to welding the materials. The present invention relates to a device for controlling heating or cooling.

SUMMARY OF THE INVENTION It is an overall object of the present invention to include a material heating and cooling device with enhanced control of material temperature, with features that completely heat the entire volume without internal temperature differences in the material. It is an object of the present invention to provide a welding system for materials having the following properties.

Another object of the invention is to be small enough to be mounted on the robot arm adjacent to the welding nozzle and to provide control of the temperature at the dosing nozzle without disadvantages such as heat loss or heat input during passage of the material through the intermediate conduit. It is an object of the present invention to provide a material heating device that can be used in a system that can be used.

Yet another object of the present invention is to provide a material heating device that is inexpensive to assemble, has a long working life, and is highly reliable.

[Means to solve the problem]

Other features and advantages of the invention will be detailed below with reference to the accompanying drawings.

The system 10 shown in FIG. 1 is for welding beads 12 of structural epoxy to the interior surfaces of a number of door panels 14 that are sequentially passed along a conveyor 16. The robot arm 18 is in a material welding position adjacent to the conveyor 16 and is movable with a wide range of degrees of freedom by controlling the robot controller 20. As far as I have described above, the first
Line 10 is shown only as an example of an environment in which a system embodying the present invention may be used.

According to a preferred embodiment of the invention, the material to be deposited as bead 12 is deposited by an air-driven positive displacement, high volume, high pressure, double acting, suction assisted, double elevated, low shear stress piston pump 22; The pump introduces material from each drum 24. Valves 26 and 28 are provided to allow replacement of one material drum while continuing operation on the other. The material is pressurized via conduit 30 from pump 22 to material conditioner 32 to heat the material to a high temperature so as to weld it to panel 14, and then via conduit or hose 34 to extrusion nozzle 36. Nozzle 36 is carried on the distal end of robot arm 18 and, in accordance with a major feature of the invention, material conditioner 32 is small in size to reduce heat during material transfer from conditioner 32 to nozzle 36 via conduit 34. It can be carried on the robot arm 18 in a position adjacent to the extrusion nozzle 36 to minimize losses. The material conditioner 32 is
It is connected to a control package 38 having an electronic control device, described below with reference to FIG. 2, and other devices suitable for selectively controlling the temperature of the material passing through the conditioner 32.

The material conditioner 32 shown in FIGS. 2 and 3 includes a generally cylindrical hollow enclosure 40 having side walls 42 and a pair of axially opposing end walls 44,46. A pair of alignment brackets are welded or secured to axially spaced locations on the enclosure sidewall 42 and a strap 50 for attaching the material conditioner 32 to the robot arm 18 is adjustably connected to each bracket 48. . A helically coiled tube 54 made of stainless steel tube stock has a uniform
It consists of a number of diameter and pitch coils 56 disposed within the interior 52 of the enclosure 40 generally in the direction of the moving axis.

The tube 54 has axially opposed coil inlet and outlet ends 58.
60 and is suspended within the enclosure 40 . A suitable attachment is that parts 62, 64 are carried by end walls 44, 46 and connect tube ends 58, 60, respectively, to conduit 30, 34 (FIGS. 1 and 2). The electric heater 66 includes a base 68 mounted approximately centrally in the enclosure end wall 46 and a heating element 7 extending therefrom into the enclosure interior 52 approximately centrally of the coil 56.
has 0. Temperature sensing device 72 has a base 74 mounted approximately centrally in enclosure end wall 44 and a temperature probe 76 extending into enclosure volume 52 approximately in the center of tubing coil 56 . The electric heater 66 and the temperature sensing device 72 are connected to an electronic control device 78.

The inlet fitting 80 and outlet fitting 82 are attached to the end wall 44.46.
are respectively provided to circulate a heat transfer fluid through the hollow interior 52 of the enclosure 40. The outlet fittings 82 include a cooler 84, a pump 86, a solenoid valve 88 and a flow indicator 9.
0 to the inlet fitting 80 by a closed loop suitable fluid conduit. Cooler 84 includes a compressor and a suitable refrigerant for cooling the heat transfer fluid passing therethrough. Cooler 84 , pump 86 , and solenoid valve 8 each receive control inputs from electronic controller 78 . Similarly, the electronic controller 78 receives input from the temperature adjustment mechanism 92 to bring the temperature within the enclosure 40 to a value selected by the operator for increasing the temperature of the epoxy passing through the coiled tube 54, and also to a predetermined temperature. The output is connected to a suitable alarm 94 for indicating temperatures above a value, below a predetermined value, and other necessary alarm conditions. The heat transfer fluid is preferably a mixture of glycol and water, but may be other types of media as required by operating temperature parameters.

In operation, the welding temperature at bead 12 (FIG. 1) is typically specified by a process engineer based on technical data regarding the particular materials used, the actual design used, operating experience, and other factors. The temperature of the material within conditioner 32 is typically set at a somewhat slightly elevated temperature by temperature adjustment mechanism 92 to accommodate heat losses in tube 34 and extrusion nozzle 36. For example, if a welding temperature of approximately 37°C (10°F) is desired at bead 12,
The temperature adjustment mechanism 92 initially adjusts the temperature to approximately 41°C (15”F).
) and then readjust it above or below that temperature based on actual measurements, process experience, etc.

With the temperature thus set, a thermoset material, such as a structural epoxy, is forced through the conditioner 32 under pressure from the pump 22. As the material flows through the coil 56, the electric heater 66 is actuated by the electronic controller 78 to heat the heat transfer fluid within the enclosure 40, causing the heat transfer fluid to transfer thermal energy to the coil 56 and then Transfer to epoxy material. Temperature sensing device 72 sends an electronic signal representative of the temperature of the heat transfer fluid to electronic control unit 78.

An electronic controller 78, preferably having a microprosensor-based controller, includes a cooler 84, a pump 86,
A solenoid valve 88 and appropriate programming for electric heater 66 are provided to maintain the heat transfer fluid within enclosure 40 surrounding coiled tube 54 at the desired operating temperature.

According to a significant advantage of the present invention, the coiled tube 54 automatically mixes the epoxy material as it passes through it, thereby imparting a shear center force on the material that activates the thixotropic properties of the material. This greatly facilitates heat distribution throughout the material.

This uniform distribution of heat without shearing is important to obtaining and maintaining the desired properties of the epoxy material. The length of coiled tube 54 within enclosure 40 is such that the material remains in conditioner 32 for a sufficient period of time to maintain uniform heating, temperature rise, and a predetermined flow rate of material preset by the process engineer. selected. What has been determined through experiments in developing the present invention is:
The optimum time for the material to reside in the conditioner 32 is approximately 3.2 times the material flow rate per hour.

For example, if the flow rate is set at about 410 cubic centimeters (25 cubic inches) per hour, the length and inner diameter of coiled tube 54 are selected to hold about 1311 cubic centimeters (80 cubic inches) of epoxy. The coil pitch is selected to balance the fluid back pressure resulting from the pitch reduction with the increased axial length of the enclosure 40 required by the pitch increase.

[Brief explanation of the drawing]

1 is a partial perspective view of a system for welding thermosetting materials in an automated production process in accordance with a preferred embodiment of the present invention; FIG. 2 is a partial schematic cross-sectional view of the material heating apparatus of FIG. 1; and FIG. 2 is an end view of the material heating device shown in FIGS. 1 and 2. FIG. 10... Welding system, 12... Epoxy bead,
DESCRIPTION OF SYMBOLS 14... Panel, 16... Conveyor, 18... Robot arm, 20... Control device, 22... Piston pump, 24... Drum, 26.28... Valve, 3
0, 34... Conduit, 32... Conditioner, 36
... Nozzle, 4° ... Hollow surrounding body, 48 ... Bracket, 54 ... Coil winding tube, 56 ... Coil, 6
6 River electric heater, 72... Temperature sensing device, 76... Temperature probe, 78... Electronic control device, 84... Cooler, 8
6...Pump, 88...Solenoid valve, 90...
Flow rate indicator, 94 river alarm.

Claims (25)

[Claims] (1) A device for supplying a fluid thermosetting material under pressure, a device for heating the material to a higher temperature than the surroundings, a device for welding the material to a base material at the high temperature, and a device for welding the material to a base material at the high temperature; a conduit device for delivering the material to the heating device and further to the welding device, the material heating device comprising: a hollow enclosure having an interior volume; and a conduit device suspended within the enclosure; a helically coiled tube having interlocking first and second tube ends; an electric heater disposed within the enclosure and responsive to applied power for heating the volume; and for transmitting an electronic signal as a function of temperature. an electronic controller having a temperature sensing device disposed in the volume and a device responsive to the electrical signal to selectively apply power to the electric heater to maintain the temperature within the volume at the elevated temperature; A system for welding a flowable thermosetting material to a substrate, the system comprising: (2) A patent in which the volume of the surrounding body is substantially cylindrical, and the helically coiled tube has axially opposed ends that suspend the tube within the volume and is connected to the conduit device. The system according to claim 1. (3) The coiled tube is suspended approximately in the center of the volume, and the electric heater and the temperature sensing device are located within the coiled tube at approximately the center of the volume and the tube. The system described in Scope No. 2. 4. The system of claim 3, wherein said electric heater comprises an elongated heating element extending from one end of said enclosure approximately in the center of said coiled tube. 5. The system of claim 4, wherein the coiled tube is a coil of uniform diameter and pitch. (6) In a system for welding the material at a predetermined constant flow rate, the supply device has a pump for supplying the material at the predetermined constant flow rate, and the coiled tube is placed in the heating device at a predetermined rate. 6. The system of claim 5, having a diameter and length selected to retain the material for a predetermined amount of time at a flow rate. (7) The system of claim 6, wherein the residence time is approximately 3.2 hours. 8. The system of claim 7, wherein the electronic control device further includes a device for selectively adjusting the temperature within the volume. 9. The system of claim 5, wherein the heating device further includes a heat transfer fluid within the volume to enhance heat transfer from the heating device to the coiled tube. 10. The system of claim 9, wherein the heating device further includes a device for lubricating the heat transfer fluid on the outside of the enclosure. (11) The system of claim 10, wherein the heat transfer fluid is a mixture of glycol and water. 12. The system of claim 10, wherein the circulation device defines a fluid inlet and a fluid outlet at opposite ends of the volume. (13) Claim 10, wherein the circulation device is coupled to the electronic control device for selectively cooling the heat transfer fluid.
System described in section. (14) The electronic controller includes a microprocessor-based controller having a device responsive to electronic signals to select and operate a heating device and a cooling device to maintain the heat transfer fluid at a predetermined temperature. 14. The system according to claim 13, wherein: 15. The system of claim 1, wherein the heating device further includes a heat transfer fluid within the volume to enhance heat transfer from the heating device to the coiled tube. 16. The system of claim 15, wherein the heating device further includes a device for circulating the heat transfer fluid outside the enclosure. 17. The system of claim 16, wherein the circulation device includes a device forming a fluid inlet and a fluid outlet at opposite ends of the volume. 18. The system of claim 17, wherein the circulation device includes a device coupled to the electronic control device for selectively cooling the heat transfer fluid. (19) A patent in which the electronic control device is a microprocessor-based control device having a device responsive to the electronic signal to selectively operate a heating device and a cooling device to maintain the heat transfer fluid at a predetermined temperature. A system according to claim 18. (20) Claim 1, wherein the electronic control device further includes a device for selectively adjusting the temperature within the volume.
System described in section. (21) the supply device includes a pump for dispensing material at a predetermined constant flow rate, and the coiled tube has a diameter and length selected such that the material remains within the heating device for a predetermined time at a predetermined flow rate; 2. A system according to claim 1, wherein the system has a welding method for welding materials at a predetermined constant flow rate. (22) The system according to claim 21, wherein the pump is a piston pump. (23) The system according to claim 21, wherein the residence time is approximately 3.2 hours. (24) The system of claim 1, wherein the supply device includes a piston pump. (25) The system according to claim 1, wherein the material welding device includes an extrusion nozzle.