Apparatus for butt-welding of plastic parts.

The invention relates to a device for end-face Welding of plastic parts, as in the preamble of Claim 1 is described.

In the publication "Kunststoffe" 76 (1986), 4, pp 318 to 323, are devices for frontal welding described plastic parts of the aforementioned type, which have heating elements for radiant heating.

These known heating elements have a size as un uniform and also temperature-dependent emissivity on what in particular to be welded at difficult Plastic materials is disadvantageous.

From EP-A1-03 13 731 is a further means the type mentioned famous, which in order to a connecting tubular parts ring-shaped heating having device. Here is a uniform heating to a predetermined temperature of the end faces of the tubular parts is not possible because the heat radiation surfaces of the heating device from the end faces too far are removed and have a different distance.

By DE-GBM-74 25 376 is a device for welding become known from hollow profile moldings, wherein the heater formed as a filament heat radiating generator is designed linearly. different for each union hollow cross section therefore has a specially adapted Heater may be used.

In DE-88 06 839 U1 is a heating element for welding machines for heating of plastic parts by direct contact described, wherein a film coating the plate surface the heating element to protect against sticking. For the Changing soiled sheets, the Schweißeinrich processing a very complex device.

By EP-02 08 913 A1 a device for is stirnsei term welding of molded articles of thermoplastic become known plastic, wherein the melting of the Plastic material by direct contact with a heating plate occurs. Between the heater and cooling plate is a plate made of insulating material, such. as well ceramic, arranged. A disadvantage is that the solidification the molten material, the heating will be switched off must, while still a contamination of the heating surfaces by the molten material can occur.

Furthermore it is known from DE-37 12 128 C2 a Spritzgiesswerk convincing for making lenses, mirrors, etc. Plastic be with an electrically heated mold insert made of ceramic known become, by means of which a high optical top to be achieved surface quality of the lenses.

Such ceramic inserts for an aforementioned Means for frontal Veschweißen unsuitable because of flowing through it with electric current ceramic insert For safety reasons, would not be permitted and the erforder union welding temperatures so would hardly attainable.

Object of the present invention is to provide a Device of the type mentioned, whose Heizvorrich tion to the proper welding also are difficult to welded thermoplastic materials such. B. Perfluralkoxy cop., Ethylene-chlorotrifluoroethylene-Cop., Polyvinylidene fluoride and polyvinyl chloride is suitable and wherein the heater for uniform heating the surfaces to be welded different dimen solutions formed.

According to the invention this object is achieved by the characterizing Features of claim 1 dissolved.

Particularly advantageous embodiments of the invention are in in the dependent claims.

Due to the good thermal conductivity of copper is the heater rapidly heated up, whereby for a swift and uniform heating of the plate, the juxtaposed Cartridge heaters provide.

The ceramic layer guarantees a constant radiation the heat energy to the entire surface where the Heat-radiation intensity - also called emissivity - is increased so that a better efficiency of the heating device is achieved. In addition, due to the construction and the materials a very narrow temperature band on the Surface of the heater respected. The desired Temperature is determined by the arrangement of at least one Thermocouple which is operatively connected with a control device , has been maintained within narrow limits.

The invention is illustrated in the accompanying drawings and described below.

It shows

<b>Fig.</b> 1 means for frontal welding Plastic parts in perspective simplified view,

<b>Fig.</b> 2 a variant of the in <b>Fig.</b> 1 shown means

<b>Fig.</b> 3A to 3D workflow when welding tubular parts with the Einrich tion in accordance <b>Fig.</b> 1 and <b>Fig.</b> 2 in four schematically Working positions shown.

The <b>Fig.</b> 1 shows a device for end-face Ver welding of tubular parts such. as an Art fabric tube <b>1</b> with a molding <b>2</b>,

The device comprises a base frame <b>3</b> to, on which a fixedly arranged fixture <b>4</b> and on a carriage <b>6</b> axially movable chuck <b>5</b> is is classified.

A heater <b>7</b> is attached to a pivotable lever as <b>8th</b> arranged like support part and by means of a handle <b>9</b> between the ends of the clamped rohrför shaped parts <b>1</b>. <b>2</b> pivoted.

The lever <b>8th</b> is on an axis <b>10</b> pivotally and against Pressure of a spring <b>11</b> axially towards the fixed jig <b>4</b> mounted.

The heater <b>7</b> is as an infrared heater formed, the front ends of the rohrför shaped parts <b>1</b>. <b>2</b> contact by means of heat or infra red rays are heated.

The heater <b>7</b> has a radiator <b>12</b> from a a ceramic layer <b>14</b> provided metal plate <b>13</b> in which, for. example, from copper or a steel-made is. In the metal plate<b>13</b> are in several holes electrically heatable heating cartridges <b>15</b> arranged, which has a fairly uniform heating of the metal plate <b>13</b> ge guarantee. At least one, preferably two thermal sensor <b>16</b>, Are in the metal plate <b>13</b> arranged with a control device for the heater <b>7</b> wirkver prevented. The ceramic layer<b>14</b> preferably has a thickness from 0.1 to 0.6 mm, and ensures a uniform Radiation of heat energy to the entire surface. At the radiator <b>12</b> are stop cam <b>17</b> arranged which by axial displacement of the heater <b>7</b> to rest the jigs <b>4</b>. <b>5</b> can be brought. At the frontline side of the base frame <b>3</b> is a round rod <b>18</b> fixed, on which is pivotally and axially movable one stop <b>19</b> and a cutting tool <b>20</b> are arranged.

stop <b>19</b> and cutting tool <b>20</b> are between the jigs <b>4</b>. <b>5</b> pivoted, said cutting Tool <b>20</b> manually by means of a ratchet or mo is toric driven and cutting on both sides to Machining of the front ends of the tubular parts <b>1</b>. <b>2</b> having.

When in the <b>Fig.</b> 2 shown embodiment is the carriage <b>6</b> for the tensioning device <b>5</b> on a guide <b>22</b> arranged, which preferably consists of two round guide Stan gen is.

Between the two clamping devices <b>4</b> and <b>5</b> is on the guide <b>22</b> a movable carriage on this <b>23</b> With a transverse guide <b>24</b> arranged. On this cross guide<b>24</b> is a holding part <b>25</b> for the heater <b>7</b> either manually or mechanically by means of a further not Displacement drive between the two shown Jigs inserted.

The heater <b>7</b> comprises, as to <b>Fig.</b> 1 Already! wrote a radiator <b>12</b> cartridge heaters <b>15</b>. thermocouples <b>16</b> and stop cam <b>17</b> on.

The sled <b>23</b> with the heater <b>7</b> is toward the tubular member axis by displacing the slide <b>6</b> against the pressure of the spring <b>11</b>, how to <b>Fig.</b> 3c describes ver pushed.

On the end faces of the two clamping devices are to beating <b>19</b>a displaceable or pivotably arranged and serve to align the to be clamped, tubular parts <b>1</b> and <b>2</b>,

The cutting tool <b>20</b> is at one of the carriage <b>23</b> attachable bearing part <b>25</b> arranged and radially between jigs <b>4</b>. <b>5</b> insertable.

To move the jig <b>5</b> with the sled <b>6</b> is a lever <b>26</b> arranged.

The execution of the welding operation, as hereinafter described, and in the <b>Fig.</b> 3A, <b>3</b>B, <b>3</b>C and <b>3</b>D shown.

First you have under <b>Fig.</b> 3A the stop <b>19</b> or the two attacks <b>19</b>a (<b>Fig.</b> 2) between the two Spannvorrich tions <b>4</b>. <b>5</b> are pivoted. Then the rohrför can shaped parts <b>1</b>. <b>2</b> are clamped, while before Clamping be axially displaced until it stops. at the in <b>Fig.</b> 1 device shown here has the on the carriage <b>6</b> sliding jig <b>5</b> against the attack <b>19</b> are pressed.

After successfully spans the movable Spannvor direction <b>5</b> cut back and the stop <b>19</b> out swings. In the embodiment of<b>Fig.</b> 2 is only the Pivoting back of the stops <b>19</b>a required.

To modify the end-face ends of the tubular parts <b>1</b>. <b>2</b> the cutting tool <b>20</b> pivoted or radially inserted (see <b>Fig.</b> 3B). The cutting tool<b>20</b> by means of the movable chuck <b>5</b> to the front ends of the parts <b>1</b>. <b>2</b> pressed, wherein simultaneously by turning the cutting tool <b>20</b> by means of a ratchet machining the ends on a Fixed dimension occurs.

The processing is completed when the cutting tool <b>20</b> at the two clamping devices <b>4</b>. <b>5</b> bears.

After the retraction of the slidable clamping device <b>5</b> is the processing tool <b>20</b> pivoted or to back pushed and then the front ends to sow cleanliness and dimensional accuracy can be verified.

The heated in the meantime radiator <b>12</b> becomes by means of the handle <b>9</b> or a drive between the parts to be welded <b>1</b>. <b>2</b> brought. By axially Ver push the carriage <b>6</b> comes the jig <b>5</b> to System to the stop cam <b>17</b> the radiator <b>12</b>, in which the heater <b>7</b> against the pressure of spring <b>11</b> continue will be postponed until the stop cam <b>17</b> on the other Side of the radiator <b>12</b> to the jig <b>4</b> request (Please refer <b>Fig.</b> 3C).

In this position, the two surfaces of the heater <b>12</b> to the front ends of the to ver welded parts <b>1</b>. <b>2</b> one for a rapid heating set at a distance so as not to touch the heating body <b>12</b> with the parts <b>1</b>. <b>2</b> takes place. After a set heating time, the carriage <b>6</b> fast retracted slightly and the heater <b>7</b> from the Welding area returned to its rest position. Then are the parts to be welded by moving the jig <b>5</b> pressed against each other, with stops <b>21</b> on the clamping devices <b>4</b>. <b>5</b> limit the travel (Please refer <b>Fig.</b> 3D). By adjustable stops<b>21</b> and a adjustability of the welding temperature can, depending on ver welded materials, optimum weld be produced, whereby the smallest possible weld bulges occur.

By unillustrated drive for all the movements and program control is car the entire device matisierbar.