DE202007014873U1 - Plastic welder for welding workpieces made of plastic - Google Patents

Abstract

Plastic welding machine for welding workpieces made of thermoplastic material with at least one electric heating device (28, 43) for or melting of thermoplastic material and with a Control means (40, 41) for variable control with the electrical power supply to the at least one heating device (28, 43), characterized in that the control device (40, 43) 41) has a wave packet control.

Description

The The invention relates to a plastic welder for welding workpieces made of thermoplastic Plastic with at least one electric heater for On or melting of thermoplastic material and with a control device for variable control of the electrical Power supply to the heater.

To the Welding workpieces made of thermoplastic Plastic are different according to the type of workpieces Plastic welding equipment known. You can basically divided into two genera, namely those plastic welding machines in which the surfaces to be joined or melted and then be pressed together without any additional welding agent is used, and in those plastic welding equipment, where the workpieces have a weld bead, the melted from in the welding machine thermoplastic Plastic material and is supplied to the weld, get connected. In the latter genus may additionally be provided that while also connecting to each other Surfaces are melted to a good connection of these surfaces to produce with each other and with the welding bead.

All plastic welding devices of these two types have heating devices with which the workpieces themselves or just additional welding agent on or is melted. In the former genus, one can distinguish between those in which the temperature carrier is air, that is, in which heated by the heater air and then directed to the surfaces to be joined, and those in which the temperature carrier is a metal block, for example in the form of a heated blade or a heating wedge is. Hot air welding machines are for example off DE 201 22 527 U1 and DE 297 16 394 U1 , but also from the EP 1 254 759 A2 and the DE 20 2006 014 390 U1 known, the latter welding equipment for the welding of plastic sheets or films are formed. For this purpose, plastic welding equipment with electrically heated heating wedges are known (see. DE 296 20 216 U1 ). For the butt welding of plates plastic welding equipment are known in which the front sides to be welded by means of a heated sword or melted and driven after removal of the heating sword against each other (see. EP 0 595 213 B1 ).

The above second-mentioned type are mainly hand-welding devices in which a plastic wire is supplied to a plasticizing device provided with a heating device and is plasticized there and is ejected from the hand-welding device in this form (cf. DE 28 23 171 A1 . DE 38 35 250 C1 and DE 10 2004 043 376 A1 ). In general, these plastic welding units are additionally provided with a hot air device, brought in the sucked ambient air in a second heater to melting temperature and ejected in the region of the mouth of the plasticizing the plastic welding machine. The hot air ensures the melting of the workpieces in the weld area. Such extruder welding machines are also used in circular welding machines (cf. DE 39 10 099 C2 ), in which the plastic welding device is part of a large device, so it is not performed by hand.

The Heaters of plastic welding equipment are usually connected to a control device, via from the outside the power supply and thus the heating power the heater are adapted to the respective requirements can. In this way you can with the plastic welding equipment different plastics are welded, the divergent Have melting temperatures. Besides, it is occasional required, the heating power to the prevailing ambient tempera ture to adapt to a melting or melting of the plastic material sure.

at takes the well-known plastic welding equipment the adaptation by means of mechanical or electronic relays, the depending on the required power, the power supply to the heater switch on or off. The supplied electrical power then results as an average of the duration of the input and output cycles, the shorter the supplied power should be. The cycles are in of the order of a few seconds but also go into the minute range, if only one low heat output is required.

In order to ensure a possible rapid onset or melting of the plastic material, be it the workpieces themselves or be it the supplied welding agent, the heaters must provide high heat outputs. This is especially true for the above-mentioned manual welders, which have a second heater for additional air heating. In the case of the known relay control, considerable repercussions in the form of voltage drops when switching from an exhaust cycle to a single cycle and vice versa thus arise in the region of the power take-off from the supply network. This in turn has the consequence that parallel-operated power consumers, for example, the electric motors of the hand welding devices for the purpose of promoting the plasticized welding agent, Ge bläsemotoren etc., considerable swan are subjected to the power consumption, which are also acoustically perceptible. This may also affect other devices powered by electrical equipment in the room. This can lead to considerable disruption in the plastic welders themselves, but also in the adjacent operated devices to the point that an inferior quality welding is obtained.

Of the Invention is based on the object plastic welding equipment of the type mentioned above in such a way that the repercussions on the supply network and thus on the operation of other electricity consumers drastically reduced.

These The object is achieved according to the invention the control device has a wave packet control, preferably one that works on the network phase, and above all so that at a power output below 100% only whole waves or wave packets be suppressed. In such a wave packet control according to the requested performance whole voltage waves suppressed, and only to the extent, as necessarily necessary. For example, at 90% power every one Tenth voltage wave suppressed, at a 50% power every second voltage wave. As with the usual network frequency of 50 Hz a voltage wave only 20 msec. lasts, is the power consumption the heater is extremely even, so that parallel electrical consumers, such as belonging to the plastic welding equipment Engines or parallel operated devices in their performance not be affected, as there is hardly any voltage fluctuations comes. Audible effects do not occur.

In the drawing, the invention is based on an embodiment illustrated in more detail. Show it:

1 a longitudinal section through a manual welder for welding plastic workpieces,

2 a cross section through the welder according to 1 and

3 Five voltage waveforms for different power output.

The manual welder shown in the figures 1 consists of two main parts, namely a drill-like drive 2 and a mounted on the output side attachment 3 which of the drive 2 is removable.

The drive 2 has a motor housing 4 in which an electric motor with horizontal output shaft 5 is encapsulated. At the rear end of the motor housing 4 closes below a handle 6 on, on the handling of the hand welder 1 done in the manner of a drill. Over the bottom free end of the handle 6 a not shown here electric cable is introduced, via which the electric motor and the heater described below is supplied with electrical energy. At the handle 6 there is a control switch 7 , via which the speed of the electric motor can be steplessly controlled as a function of its position.

The attachment 3 consists essentially of a conveyor 8th and a plasticizer 9 , The conveyor 8th has a cylindrical housing in its basic form 10 , the drive side with a connection piece 11 is provided over the engine housing 4 slipped over and there with this over a pipe clamp 12 is stuck. Through the conveyor housing 10 extends a conveyor screw 13 , the rotation with the output shaft 5 is connected and outside a screw thread 14 having. Between screw thread 14 and conveyor housing 10 becomes a conveyor channel 15 formed, in the drive-side end of which a not shown, outgoing supply channel for the introduction of a plastic wire opens. A plastic wire inserted into the feed channel becomes a rotary motion of the feed screw 13 in the conveyor channel 15 retracted, wherein the plastic wire the conveying channel 15 happens and at the same time the screw thread 14 feared in the material of the plastic wire. As a result, the plastic wire in the longitudinal direction, ie in the direction of the plasticizing 9 transported.

The plasticizer 9 has a plasticizing tube 16 on, by means of screws 17 . 18 axially against the plastifizierseitige end side of the conveyor housing 10 clamped and in this way with the conveyor housing 10 connected is. Through the plasticizing pipe 16 extends a screw conveyor 19 , rotatably with the conveyor screw 13 and consequently with the output shaft 5 connected is. The screw conveyor 19 has a worm thread on the outside 20 on. Between conveyor screw 19 and plasticizing pipe 16 becomes a plasticizing channel 21 included with the delivery channel 15 of the funding section 8th is connected and forms together with this and the supply channel for the plastic wire, not shown, a through-channel.

Towards the free end, the plasticizing pipe closes 16 a welding shoe 22 on, about screws 23 . 24 against the front end of the plasticizing tube 16 is tense. The welding shoe 22 is at an ejection channel 25 interspersed, the a continuation of the plasticizing channel 21 represents and that in the plasticizing 21 plasticized plastic material is ejected in the form of a plastic bead.

The conveyor housing 10 and the plasticizing pipe 16 consist of an aluminum alloy, namely an AlZn5.5MgCu alloy. The surfaces of the conveyor housing 10 in the area of the conveyor channel 15 and the plasticizing tube 16 in the area of the plasticizing channel 21 are with protective layers 26 . 27 which have been prepared by converting these surfaces by hard anodization into an aluminum oxide layer of the order of 50 μm. Because of these protective layers 26 . 27 the surfaces are extremely resistant to abrasion and therefore withstand the stresses caused by the plastic material conveyed through the through-channel - initially in solid form and then plasticized - for a long time. It is understood that even the inside of the ejection channel 25 may be provided with such a protective layer.

The outside of the plasticizing pipe 16 is from a heater 28 practically completely surrounded. The heater 28 consists of two heating modules 29 . 30 as half shells 31 . 32 are made of solid material (aluminum alloy) and each have two holes in the axial direction, in the heating elements 33 . 34 respectively. 35 . 36 are used. In this case, at least one half shell 31 . 32 a temperature sensor, which is connected to the control device described below. About the controller, a certain temperature can be adjusted. A control circuit ensures the maintenance of this temperature.

The half-shells 31 . 32 lie with their convex inner surfaces flat on the outside of the plasticizing 16 so that a good heat transfer from the half-shells 31 . 32 on the plasticizing pipe 16 is guaranteed. The half-shells 31 . 32 are over a pipe clamp 37 with the plasticizing pipe 16 braced. After removal of the pipe clamp 37 and after separation of the electrical connection, the half shells 31 . 32 easily from the plasticizing pipe 16 If necessary, ie in the event of a defect, replaced by one or two new half-shells.

On the motor housing 4 attached is a control box 38 in which a circuit board 39 is arranged on the electronic components 40 . 41 for the control of the manual welder 1 are arranged. As in particular from 2 can be seen, connects to the control box 38 below a heat exchanger housing 42 at. In the heat exchanger housing 42 a heat exchanger is arranged on the heat generating electronic controls are arranged in the operation. To the heat exchanger housing 42 a hose can be connected that leads to an external fan. The fan delivers fresh air into the heat exchanger housing 42 so that the electronic elements are cooled. Part of the airflow can also be via the electronic components 40 . 41 be directed. Part of the air goes into an air heater 43 where the air is strongly heated and via an adjoining air duct 44 to the welding shoe 22 is directed.

From the control box 38 goes a cable protection tube 45 towards the heater 28 , The cable protection tube 45 contains an electrical cable that provides electrical power to the heating elements via appropriate connections 33 . 34 . 35 . 36 passes, as well as another, going to the temperature sensor cable.

In operation, the hand welder 1 with the welding shoe 22 applied to the weld to be provided. By switching on the electric motor, the feed screw 13 and the screw conveyor 19 set in rotational motion. As a result, the introduced in the feed channel plastic wire in the delivery channel 15 retracted and towards the plasticizer 9 transported. At the same time, the heater 40 supplied with electricity, so that designed as a resistance heating heating rods 33 . 34 . 35 . 36 heat and heat pipe via the plasticizing 16 bring to a temperature which is above the melting temperature of the retracted plastic wire. At the same time, the external fan is put into operation and the air sucked in the air heater 43 heated and over the sweat close to the outlet opening of the air duct 44 directed to the area of plastic plates to be welded. As a result, intended for the weld areas of the workpieces to be welded are softened.

The in the plasticizing pipe 16 entering plastic material is by heating through the heater 40 melted and by the rotational movement of the screw conveyor 19 in the direction of the ejection channel 35 transported. The resulting frictional heat supports the heating of the plastic material. That from the ejection channel 35 exiting, plasticized plastic material then forms the welding agent, which connects to the softened by the hot air surfaces of the workpieces to be welded.

The electrical components 40 . 41 include a wave packet controller for the electrical supply to the heater 28 and the air heater 43 , The wave packet controller has an electronic relay that has a network phase accurate In the "On" state, each half-cycle is ignited in the voltage zero crossing, whereby only complete full-wave, consisting of positive and negative half-wave, is controlled.

In 3 the voltage curves are shown for different power requirements. At only 10% power between two full waves - exemplified with 46 designated - nine full waves suppressed. At 25% power, only every fourth solid shaft becomes 46 let through, while in between three full waves are suppressed. At 50% power every second full wave is suppressed, at 75% power every fourth, while at 90% power after nine full waves 46 a full wave is not allowed through. There are ten full waves equal to 0.2 seconds. With the help of this wave packet control noticeable voltage fluctuations are avoided even at low power, so that parallel electrical consumers are not disturbed, so keep their power.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 20122527 U1 [0003]
• - DE 29716394 U1 [0003]
• - EP 1254759 A2 [0003]
• - DE 202006014390 U1 [0003]
• - DE 29620216 U1 [0003]
• EP 0595213 B1 [0003]
• DE 2823171 A1 [0004]
• - DE 3835250 C1 [0004]
• DE 102004043376 A1 [0004]
• - DE 3910099 C2 [0004]

Claims (4)

Plastic welding device for welding workpieces made of thermoplastic material with at least one electric heating device ( 28 . 43 ) for the melting or melting of thermoplastic material and with a control device ( 40 . 41 ) for variable control with the electrical power supply to the at least one heating device ( 28 . 43 ), characterized in that the control device ( 40 . 41 ) has a wave packet control. Plastic welder according to claim 1, characterized in that the wave packet control network phase accurate is working. Plastic welder according to claim 2, characterized in that the wave packet control such is designed that at a power output below 100% only full waves or full wave packets are suppressed. Plastic welding apparatus according to one of claims 1 to 3, characterized in that the suppressed solid waves ( 46 ) or full wave packets are as small as possible.