Portable thermo-plastic welding machine and method

A machine and method for welding thermo-plastic rain gutters or other work pieces together. The machine includes a frame assembly and a protective shroud. Handles or a wheeled carriage are provided for transporting the machine to a work site. A stationary plate and a moveable plate are each secured to the frame assembly. Work piece holders and corresponding clamps specially configured for clamping rain gutters or other work pieces are disposed on the stationary and moveable plates together with a spacer plate for positioning and holding the ends of two work pieces in a position for welding the ends together. A heater is provided for heating the ends of the work pieces to a desired welding temperature and a press is provided for pressing and holding the molten ends of the work pieces together for welding.

FIELD OF THE INVENTION

The present invention is directed to machines and methods for welding plastic articles together and in particular to portable machines and methods for welding rain gutters and other non-cylindrical multi-faceted thermo plastic building products together at a work site.

BACKGROUND OF THE INVENTION

Many products used in the construction industry that were traditionally formed of metal or other materials can be replaced with products that are formed of plastic. Rain gutters for instance were traditionally made from metal and are now available in plastic.

Metal rain gutters are produced using roll forming technology, which unwinds coils of flat metal stock and then drives the metal through a series of rollers and forming dies in order to bend it into the desired shape of the gutter profile. The metal gutter can be manufactured on large industrial grade equipment in a factory setting or by portable roll formers that can easily be transported to the job site for use by installers. The portable roll former allows the installers to field measure the length of gutter sections required and then fabricate the gutter to the specified length.

Plastic rain gutters are produced by an extrusion process in a large industrial setting, supported by ancillary equipment to provide the energy and means to heat the plastic to a molten state, transfer the material through forming dies and then cool the plastic to the desired profile. Based on the nature of this extrusion production process, plastic rain gutters can only be manufactured, in an economic manner, in a factory setting and then cut to predetermined lengths. The overall length of the manufactured plastic gutter sections is physically limited to lengths that can be practically stored in retail locations and then transported to job sites for installation. Lengths of 10-16 ft are most common. Plastic fittings are then used to adjoin adjacent straight sections of gutter when the system is installed on a building requiring longer lengths

Plastic rain gutters offer improved durability to that of metal rain gutters because they are dent, crack and peel resistant during installation or long term use. These gutters tend to be easier to install and are favored by “Do it Yourself” installers because they do not have sharp edges like the metal systems that can cut fingers and hands. In addition, unlike metal systems that require caulking compounds to seal adjoining gutter sections, most plastic systems use fittings with a self contained gasket system that make the installations easier.

Despite the product benefits offered by the plastic systems, trade professionals and installers generally prefer the convenience and flexibility offered by the portable metal roll forming fabrication process. As a result, most trade professionals invest in portable roll forming equipment to manufacture metal gutter to custom lengths on site. Installers are assured that once installed, the gutter will not leak along the length of the gutter. In addition, the continuous length of gutter is preferred from an aesthetic perspective offering clean, smooth visual lines along the face of a building as compared to the non-continuous appearance that results when a number of fittings are used to adjoin plastic gutter sections.

There is a need for a device that allows the trade professional to offer the product benefits of plastic rain gutters to a client while offering the installation convenience and flexibility traditionally associated with on site metal rain gutters fabricators. This need can similarly be found for other forms of plastic building products including architectural moldings and trim, wall siding and door and window frames. There is also a need for a device that is safe and simple to operate so that it may be used by non-professionals as well.

SUMMARY OF THE INVENTION

In one aspect the invention provides a machine for welding the ends of two thermo-plastic rain gutters together, the machine comprising:

a frame assembly;

a first holder disposed on said frame assembly for supporting the first rain gutter, said first holder having a cross sectional profile corresponding to the cross sectional profile of the first rain gutter;

a second holder disposed on said frame assembly for supporting the second rain gutter, said second holder having a cross sectional profile corresponding to the cross sectional profile of the second rain gutter;

a first clamp assembly disposed on said frame assembly for clamping the first rain gutter against the first holder;

a second clamp assembly disposed on said frame assembly for clamping the second rain gutter against the second holder;

a heater disposed on said frame assembly for heating the ends of the first and second rain gutters a sufficient amount to permit the ends of the rain gutters to be welded together; and

a press disposed on said frame assembly for pressing and holding the molten ends of the first and second rain gutters together so that the molten ends become welded together.

In another aspect the invention provides a machine for welding the ends of two thermo-plastic non-cylindrical work pieces together, the machine comprising:

a frame assembly;

a first holder disposed on said frame assembly for supporting the first work piece, said first mantle having a cross sectional profile corresponding to the cross sectional profile of the first work piece;

a second holder disposed on said frame assembly for supporting the second work piece, said second mantle having a cross sectional profile corresponding to the cross sectional profile of the second work piece;

a first clamp assembly disposed on said frame assembly for clamping the first work piece against the first holder;

a second clamp assembly disposed on said frame assembly for clamping the second work piece against the second holder;

a heater disposed on said frame assembly for heating the ends of the first and second work pieces a sufficient amount to permit the work pieces to be welded together; and

a press disposed on said frame assembly for pressing and holding the molten ends of the first and second work pieces together so that the molten ends become welded together.

In another aspect the invention provides a portable machine for welding the ends of two thermo-plastic rain gutters together, the portable machine comprising:

a first assembly for securing the first rain gutter and a second assembly for securing the second rain gutter;

a heater for heating the ends of at least one of the first and second rain gutters a sufficient amount to permit the ends of the first and second rain gutters to be welded together, said heater defining at least one groove that is configured to receive the end of one of said first and second rain gutters; and

a press for pressing and holding the ends of the first and second rain gutters together so that the ends may become welded together.

In another aspect the invention provides a portable machine for welding the ends of two thermo-plastic work pieces together, the portable machine comprising:

a first assembly for securing the first rain gutter and a second assembly for securing the second rain gutter;

a heater for heating the ends of at least one of the first and second rain gutters a sufficient amount to permit the ends of the first and second rain gutters to be welded together;

a press for pressing and holding the ends of the first and second rain gutters together so that the ends may become welded together; and

a flashing tool having an inclined leading edge for engaging the flashing and facilitating removal of a flashing formed when said first and second rain gutters are pressed together.

In another aspect the invention provides a method for installing thermo-plastic rain gutters on a building, the method comprising the steps of:(a) measuring the length of rain gutter required;(b) selecting two or more rain gutter sections for forming said desired length of rain gutter;(c) welding said rain gutter sections together end to end; and(d) securing said length of welded rain gutter to said building.

DETAILED DESCRIPTION OF THE INVENTION

A portable thermo-plastic welding machine in accordance with the present invention is shown generally at20in the Figures. The machine20is adapted for welding together thermo-plastic work pieces22such as rain gutters (as shown in the Figures), architectural moldings and trim, door frames, window frames or wall siding. The rain gutters most preferred for use with the present machine have a thermo-plastic cellular double wall construction that provides for a relatively lightweight and strong product while presenting a larger surface area for welding.

The machine20includes a frame assembly having a base24and a shroud26. The base24has front and rear side members28and30that are rigidly connected to end members32. The base24further includes cross members34that extend between the inside surfaces of side members28,30and end members32to reinforce the base24without adding substantially to its weight. The shroud26is preferably made of a shatterproof translucent or transparent material such as plexiglas that surrounds the working components of the machine20so that the machine may be operated safely. The shroud26includes openings36for inserting the respective work pieces22and removing the welded end product. The shroud26may be connected with hinges (not shown) to rear side member30to allow the shroud26to be opened to access the machine20and the work pieces22. A control panel38is located on the front side member28or any other location on the machine that is convenient for access by the operator.

The frame assembly includes handles50that are securely connected to end members34to facilitate carriage of the machine. The machine is sized so that it may be lifted by two persons and carried on the back of a pick-up truck or trailer to a work site. The machine may also be supported on its own wheeled base so that it may be towed by a vehicle (seeFIG. 12).

The machine includes a stationary plate52secured with brackets54to side members28,30. A moveable plate56is secured to runners58that ride along rails60secured to side members28,30. A plate actuator62is connected with head63to the moveable plate56and with corresponding cylinder66and piston67is secured with a clevis68to a bracket70secured to end member34. Plate actuator62acts to move the moveable plate56along runners58to one of several desired positions to press, hold and release work pieces as described further below. The preferred embodiment is provided with only one moveable plate56to simplify the overall construction of the machine however it will be understood that the stationary plate52may be replaced with a second moveable plate that is disposed on runners and that is controlled by a second plate actuator.

The machine includes first and second work piece holders80and82secured respectively to the stationary plate52and moving plate56. The work piece holders80are each configured to match the surface profile of the work piece22that is being welded. The work piece holders80,82as shown in the Figures are configured to match the profile of a rain gutter. In this configuration each work piece holder has first and second plates82and84disposed at right angles to one another and a third plate86extending at a downward and outward incline from the second plate84. The first, second and third plates are all secured to a base plate88to the respective stationary and moveable plates52,56.

First and second work piece clamp assemblies90and92are secured respectively to the stationary plate52and the moveable plate56. Each of the work piece clamp assemblies has a piston94and corresponding cylinder96supported generally at a right angle above the upper surfaces of the work piece holders80. Clamp plates98are located at the end of pistons94and arranged generally parallel to the corresponding holder plates84,86for clamping the work piece to the respective holders80. In the case of a rain gutter work piece as depicted in the Figures, the clamp plates include an upper plate100, for clamping an upper surface102of the rain gutter to the respective holder80, and a backing plate104, for clamping a back surface106of the rain gutter to the respective holder80. Backing plate includes a shoulder108for clamping a corresponding lip110extending from the rain gutter.

First and second site clamp assemblies120and122are secured respectively to stationary and moveable plates52,56. Each of the site clamp assemblies has a piston124and corresponding cylinder126supported generally at a right angle to the front side surfaces of the work piece holders80. A clamp plate128is located at the end of each piston124and arranged generally parallel to the corresponding plate of the work piece holder80for clamping the work piece to the respective holder80. In the case of a rain gutter work piece as depicted in the Figures, the clamp plate includes a side engaging plate, for clamping a side surface of the rain gutter to the respective holders.

The work piece clamp assemblies90,92and the site clamp assemblies120,122thus act together to clamp the work piece22sufficiently securely against the work piece holders80so that the subsequent welding operations can be accurately performed. It will be understood that different shapes and arrangements of clamp assemblies and work piece holders may be provided according to the particular shape characteristics of the work piece being supported (such as a moulding or wall siding).

The machine includes a spacer assembly130for providing an abutment to position the ends of the respective work pieces22in the desired location for the subsequent welding operation to be accurately performed. Spacer assembly130includes a spacer bar132that is pivotally secured at one end to side member with clevis134. A spacer bar actuating assembly136has a piston138that is secured at one end to spacer bar132using a rod clevis140and a corresponding cylinder142that is secured to the front side member. Spacer bar actuating assembly136thus acts to move the spacer bar132from an abutment position to a non-abutment position relative to the ends of the work pieces22.

The machine includes a heat plate assembly150for heating the respective ends of the work pieces22. Heat plate assembly150includes a double sided heat plate152that is secured to a bracket154and is spring biased to allow movement of the assembly150toward the stationary plate during the heating process and can accommodate imperfections in the profile cuts of work pieces22. Bracket154has runners156for guiding bracket154along a rail158. A heat plate actuating assembly160is provided for moving heat plate152between a heating position located between the two work pieces22and a non-heating position away from the two work pieces22. The heat plate actuating assembly160includes a piston162that is connected to the bracket154and a corresponding cylinder164that is connected to stationary plate52.

A flashing remover170(seeFIG. 9and description below) is provided for aiding in removal of the flashing that is formed on the welded work pieces during the welding operation. Alternatively, the flashing may be removed manually using snips or a similar removal tool.

A pump180is provided for supplying a pressurized gas or fluid to drive the piston and cylinder combinations for the clamp assemblies and the actuating assemblies. The assemblies are preferably pneumatically driven however they may instead be hydraulically, electrically or manually driven, or any combination of the above as will be understood by persons skilled in the art.

A programmable logic controller182is provided for controlling the operation of the machine. The controller182includes an adjustable thermostat184for the heat plate, an adjustable timer186for controlling the heating and welding cycles and control links188to each of the clamp and actuator assemblies. Referring toFIG. 7, one configuration for the controller circuit is shown.

Referring toFIGS. 8-11, certain portions of a welding machine20′ in accordance with another embodiment of the present invention are shown. For ease of reference, the reference numerals used to describe elements for the embodiment above are also used to identify corresponding elements of the embodiment described below. It should also be understood thatFIG. 8does not depict all of the elements of the machine20′ such as shroud26, second work piece holder82and second work piece clamp assembly92. These elements have been omitted to simplify depiction of other elements of the machine20′.

The machine20′ includes a flashing remover170defined on both the stationary plate and the moveable plate by work piece holders80and82, work piece clamp assemblies90and92and site clamp assemblies120and122. Flashing remover170includes a leading edge172defined respectively on plates82,84and86of the corresponding work piece holders80and82, plates100and104of corresponding work piece clamp assemblies90and92and plate128of site clamp assemblies120and122. The leading edge172preferably has an incline angle A of between 30 degrees and 45 degrees to direct flashing173away from the newly welded interface between work pieces22and thus facilitate removal of flashing173or formation of a weakened edge (not shown) of the corresponding flashing173. The weakened edge allows the flashing to be removed manually following the welding operation either by hand or with the aid of a cutting tool. Flashing remover170further includes a recess174for receiving the flashing during the period when the moveable plate is being moved into close proximity to the stationary plate. As shown inFIG. 10, a pair of opposing flashing removers170come into close proximity to one another to direct flashing173away from the welded interface to facilitate removal or to define a weakened edge on the flashing. Alternatively, a single flashing remover170may be defined on one of the stationery or moveable assemblies with the other forming a backing surface for the flashing173.

Referring toFIG. 11, the heater plate assembly150includes a groove176defined on at least one side of the heater plate. Groove176has a peripheral shape generally corresponding to the peripheral shape of the work piece. The groove176is adapted to receive the work piece in order to facilitate better heat displacement throughout the end of the work piece and to control formation of the weld flashing. The groove176includes inclined edges178that assist in guiding the work piece22into the groove176. It is preferred that the groove176have a depth of approximately 5 to 6 millimeters for the rain gutter work pieces22contemplated by one aspect of the present invention. The currently preferred embodiment provides a groove176on the moveable plate side of the heater plate. This is preferred so that the moveable plate, upon completion of the heating step, may be retracted sufficiently to remove the work piece from the groove176and allow the heater plate to be moved out of position prior to welding. Heater plate is preferably coated with Teflon™ or similar materials that resist adherence of the thermo-plastic material to the heater plate.

Referring toFIG. 12, another embodiment of the machine20′ is shown. The machine20′ includes a carriage having a base190that rides on wheels192. The carriage includes a tow attachment194to facilitate towing behind a vehicle to a work site.

A process of operation for the machine is shown inFIGS. 13A and 13B. The process begins with start-up of the machine by having the machine operator press the Start control200. Upon start-up the controller182positions clamp assemblies at their unclamped positions, spacer bar in its lowered position and moveable plate in its non-abutting position. Controller182also activates heat plate so that it heats to a pre-determined melt temperature that is monitored by thermostat184. The preferred temperature range for the work pieces22contemplated by the present invention is between 200 and 350 degrees Celsius and most preferably between 275 and 300 degrees Celsius for PVC rain gutter work pieces. Sensors (not shown) may be added to sense the outside temperature and to signal controller to alter plate temperature and/or heat cycle time.

Once heat plate reaches its pre-determined temperature as sensed by thermostat184, controller182causes Ready light202to be activated to signal that the machine is ready to begin the welding operation. The operator then inserts one work piece22through the opening in shroud such that it fits over the first work piece holder and its end squarely abuts spacer plate. The operator then presses the Left Clamp204button to cause the first work piece clamp and the first site clamp to each move from an unclamped position to a clamped position so that the work piece22is held firmly against the holder. The operator then inserts another work piece22, of equivalent profile as the first work piece22, through the opening in shroud such that it fits over second work piece holder and its end squarely abuts spacer plate. The operator then presses the Right Clamp206button to cause the second work piece clamp and the second site clamp to each move from an unclamped position to a clamped position so that the work piece is held firmly against the holder. Work pieces22could also be positioned or removed by pivoting open shroud26.

Once both work pieces22are clamped into position the operator presses the Weld button208to initiate the automatic welding process.

Upon sensing that the Weld button has been pressed, controller182causes space bar actuating assembly to move spacer bar away from between the work pieces and heater actuating assembly to move heat plate to a position between the work pieces. Controller182then causes plate actuating assembly to move the moveable plate towards the stationary plate a pre-determined distance so that the ends of work pieces22engage each side of the heat plate. The spring biased heating plate152moves towards work piece22on stationary plate when the work piece22on moveable plate engages heating plate152and overcomes the spring's force. Timer186is simultaneously activated to measure the time for holding the work pieces against the heat plate while plate actuator62is activated. After a pre-determined time, controller182causes plate actuating assembly to move the moveable plate away from the stationary plate so that the molten ends of work pieces22disengage from the heat plate. Instead of using timer186, sensors and/or switches (not shown) for measuring distance moved by moveable plate during the heating process may be used to determine cycle time.

Once the plate actuating assembly moves the work pieces22with the molten ends away from heat plate, controller182causes heater actuating assembly to move the heat plate away from between the ends of the work pieces. Controller182then causes plate actuating assembly to move the moveable plate a pre-determined distance so that the molten ends of each work piece abut one another. The molten ends of each work piece are compressed by plate actuating assembly into one another a pre-distance (preferably in the range of 0.5 to 5 millimeters) that is sufficient to ensure that the two ends are completely welded together and to make up for any imperfections in the square edges of the two work pieces. Concurrently, flashing remover170acts to remove or to define a weakened edge on the flashing173formed by the compressed work pieces22.

The timer186is activated when the plate actuating assembly moves the molten ends of the work pieces into abutment. After a pre-determined cooling period has passed, controller182causes the first and second work piece clamps and site clamps to be moved to an unclamped position in order to release the welded work piece and the plate actuator assembly to move the moveable plate to a position away from the stationary plate so that the machine is ready for the next welding operation. The welded work piece is then ready to be removed from the machine.

At any point during the machine operation, if the operator senses that an unsafe condition has arisen, the operator may press the emergency Stop button210to release the clamps and actuators and stop the welding operation.

In use, a person installing work pieces22, such as rain gutters, at a worksite would first determine the length of continuous work piece required and would select a sufficient number of work piece sections to form the desired length. The work pieces would then be welded together using the portable welding machine described above until the desired length of continuous work piece is obtained (some cutting of the work piece sections before or after welding may be required. The resulting welded work piece (such as a rain gutter) would then be secured to a building in known fashion.

It is to be understood that what has been described is a preferred embodiment to the invention. If the invention nonetheless is susceptible to certain changes and alternative embodiments fully comprehended by the spirit of the invention as described above, and the scope of the claims set out below.