DE8807397U1 - Device for producing a corner joint between two plastic profile strands - Google Patents

Description

Weber & Heim ··'''··' ^! ·· ^: ' ^&igr; ~ ^&igr; '°~* ;* ^&bgr; ° ⁰⁰ Munich71

Hofbrunnstrasse

German Patent Attorneys - 1 - Telephone·. (069)79)6050 European Patent Attorneys Telex: 5-212877

Fax: (0 89)7 9152

H273

Device for producing a corner joint between two plastic profile strands

The invention relates to a device for producing a corner joint connection between two plastic profile strands, for example for window or door seals, with two holders arranged on a base frame for receiving the strands, the holders each having an end face angled at half a corner angle to their longitudinal axis, with a guide device by means of which the two holders can be moved relative to one another between a first position in which the two holders are at a predetermined distance and a second position in which the two holders are in a corner joint, and with an electrically heatable cutting and welding device for separating and melting the profile strands flush with the end faces of the holders, the cutting and welding device being arranged in the first position of the holder between a working position in front of the end faces of the holders and a rest position offset next to the end faces of the holders.

A device of this type is known from DE-PS 30 24 736. Here, the guide device consists of an articulated connection of the two holders. In the open position, the two holders are pivoted apart in such a way that they are in the longitudinal direction and the front sides are arranged at an angle corresponding to the corner angle. The cutting and welding device consists of a guide device which is arranged in accordance with the angle between

the front sides formed welding blade, which is also provided with a cutting edge.

However, with many profile extruded materials, particularly if they contain a large amount of plasticizer, the problem can arise that the material scorches and residues stick to the cutting surface or to the welding blade, so that neither a perfect cutting process nor a clean melting of the cutting surfaces is possible. Since the welding blade has to be very thin due to its dual function, a large part of the heat is already removed from it during the cutting process, so that a relatively high heating output is required to compensate for this heat loss in order to carry out the welding process.

A device for welding two profile strands previously mitred in a separate cutting device is known from DE-GM 79 11 997. The holders are arranged so that they can be moved longitudinally on a guide device with their end faces aligned parallel, which in turn can be moved parallel to the end faces in order to be able to bring the profile strands to be joined together into contact with a stationary welding axe.

The invention is based on the object of specifying a device of the type mentioned at the outset, with which a perfect straightness and uniformity of the cutting surface and a reliable welding can be achieved with a simple structure and easy handling.

This task is solved by the fact that the cutting and welding device consists of a heatable pair of cutting blades and a separate welding axe and that a

An adjusting device is available with which the welding axe can be moved from the respective rest position to the working position and back again at different times after the pair of cutting blades.

A basic idea of the invention is to decouple the cutting and welding processes and to bring the relevant tools into engagement with the profile strands in opposite phases. The counter-phase ensures that both the pair of cutting blades and the welding axe can be heated up to the optimum required temperature during the alternating rest periods, which they must have when in contact with the strand material. In addition, this measure allows the welding axe to be provided with a larger mass, which stores the heat, so that the heat is applied to the plastic in an extremely uniform manner compared to the known method. Since there are no volume restrictions, it is also possible to heat the effective surfaces of the heating axe directly via heating elements, so that reliable melting can also be achieved in this way. It proves to be particularly advantageous that the pair of cutting blades and the welding axe are each heated independently of one another. In this way, the temperatures required for cutting and welding can be optimally set. This prevents cutting at a temperature that is too high for welding, which can lead to smearing or charring of the cut surface and, in the case of fine extruded profiles, can also result in undesirable distortion of the profile. If a cut surface is nevertheless created that is not completely flat, this can be compensated for by the higher temperature of the welding axe when the cut surface is brought into contact with the welding axe.

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A preferred alternative embodiment of the invention consists in that an application device for adhesives and/or solvents is provided instead of the welding axe. This has the advantage that profile materials that cannot be melted can also be processed in a simple manner and that this can be done with little equipment outlay and with extremely short changeover times. The following statements relating to the cutting axe can be transferred to the application device. It is particularly advantageous that the guide device consists of a rail guide in which the two holders are arranged so that they can be moved relative to one another while maintaining a parallel alignment of their two end faces. This measure makes it possible for the pair of cutting blades and the associated effective surfaces of the welding axe to be arranged parallel to one another, which is advantageous from a design point of view.

The time required to complete a work cycle is particularly shortened by the presence of a forced control system with which the pair of cutting blades is moved from its working position to its rest position. This also reduces the workload on the operator.

This is achieved in a particularly simple design by the fact that the adjusting device comprises a lifting rod on which the pair of cutting blades is arranged so that it can be deflected in the lifting direction under the action of a return spring and is engaged with a stroke-dependent locking device. During the lifting movement from the rest position to the working position, a rigid connection between the lifting rod and the pair of cutting blades is ensured. After reaching the working position, when the cutting blades

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pair has severed the profile strands, the locking mechanism is released so that the pair of cutting blades is automatically brought into the rest position under spring action.

The staggered movement of the pair of cutting blades and the welding axe is made particularly simple from a constructional point of view by the fact that the cutting axe is rigidly connected to the lifting rod and that the pair of cutting blades protrudes over the welding axe in the locked state and is sucked back behind the welding axe in the lifting direction in the unlocked state.

In order to obtain a particularly clean and flat cutting surface, it is advisable for the holders to consist of a lower half of the mold, which is provided on its upper side with a groove adapted to the cross-sectional shape of the profile strands to be cut, and a hinged cover which, when closed, holds the relevant profile strand in the groove, and for abutments for the pair of cutting blades to protrude beyond the end faces, which are slidably mounted on the holders in such a way that they can be deflected into a rest position flush with the end faces. The abutments have the advantage that the sections of the profile strands protruding beyond the end faces are deflected or bent by gravity when the knives engage, which can lead to undesirable deformation of the cutting surface. Their slidability allows the end faces to be butt-jointed during the welding process.

The abutments are always automatically in the ready position because they are spring-loaded against the bracket. When the corner joint is made, they are pushed outwards as soon as the two brackets are brought together.

In order to enable the pair of cutting blades to pass completely through the profile strands, it is advantageous that the abutments have a groove along the relevant end face to accommodate the free end of the pair of cutting blades. This also has the advantage that the pair of cutting blades does not become blunt as a result of engaging with the abutments.

A secure connection of the two profile strands is supported by the presence of a locking device with which the two brackets are releasably locked in the corner joint position. This locking device also cancels out the effect of the pre-tension of the abutments, which must be overcome to create the corner joint position.

Operation is made easier by the fact that the locking device has an actuating device which is connected to a cover of the holders in such a way that the locking device is unlocked when the cover is opened.

It is also advantageous that the two brackets are spring-loaded against each other in the corner joint position. The optimal contact pressure can be set using the spring force.

The invention is further described below using an embodiment shown in the drawing.

Fig. 1 shows a schematic perspective view of a device for producing a corner joint between two plastic profile strands;

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Fig. 2 shows a detail of Fig. 1 in the unlocked state;

Fig. 3 shows schematically a perspective view and 4 a partial view of the device according to Fig. 1 in two different working positions;

Fig. 5 shows in perspective view details of two holders of the device according to Fig. 1, which are arranged at a distance from each other;

Fig. 6 shows the brackets according to Fig. 5 in a corner joint position and

Fig. 7 shows schematically in a perspective view further details of the brackets according to Figs. 5 and 6.

According to Fig. 1, two holders 40 that can move relative to one another are arranged on a base frame 1, which also serves as a worktop. These holders serve as a clamping device for two plastic profile strands that are to be connected to one another. These are not shown in order to keep the figure clear. The base frame 1 has an opening between the two holders 40 through which a conditioning device, generally designated 50, and a knife assembly, generally designated 60, can be moved vertically. The conditioning device 50 is guided on a housing (not shown) so that it can move in the vertical direction using a linear guide 70. The drive devices required for this are not shown for reasons of clarity.

In the example shown, the knife assembly 60 consists of an electrically preheatable cutting blade pair 61 and the conditioning device 50 consists of an electrically preheatable

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electrically heated welding axe 51, which is arranged between the two cutting blades 62 of the cutting blade pair 61.

The linear guide 70 comprises a rail 71 fixed to the housing and a lifting rod 72 guided therein, to which the welding axe 51 is rigidly connected. The pair of cutting blades 61 is arranged on the lifting rod 72 so that it can be deflected in the lifting direction. The lifting movement is limited downwards by a stop 73.

The pair of cutting blades 62 is held in a longitudinal guide 74 on the welding axe 51.

With the help of a locking device 64, consisting of a locking pawl 65 on the cutting blade pair 61, a cooperating locking pin 66 on the welding axe 51 and a housing-fixed unlocking lug 67, a time-delayed vertical movement of the welding axe and the cutting blade pair 61 is made possible. A return spring 69 between the cutting blade pair 61 and the housing serves to automatically return the cutting blade pair 61 to the starting position shown.

Fig. 1 illustrates a rest position of the pair of cutting blades 61, which also represents the rest position of the welding axe, and in which the lifting rod 72 is completely retracted downwards. In this position, both the pair of cutting blades 61 and the welding axe 51 are located below the opposite end faces 41 of the holders 40, i.e. both tools are moved away from the area between the holders 40. The pair of cutting blades 61 is locked to the welding axe 51 by the locking pawl 65 engaging the locking pin 66.

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After a profile strand with an overhang over the end faces 41 has been inserted into the holders 40, the pair of cutting blades 61 together with the welding axe 51 are deflected upwards with a lifting movement. The cutting blades 62 protrude upwards relative to the welding axe 51 so that the cutting blades 62 come into cutting engagement with the profile strands and sever them. The cut ends can either fall through openings between the cutting blades 62 and the welding axe 51 or be removed by hand in another way.

After the pair of cutting blades 61 has reached its working position in which the profile strands are severed, a control bevel 68 on the locking pawl 65 engages with the unlocking lug 67, whereby the locking pawl 65 is unlocked and the pair of cutting blades 61 is retracted from the welding axe 51 under the action of the return spring 69 as shown in Fig. 2.

This means that only the welding axe 51 is still in its working position between the holders 40. The holders 40 can then be moved towards the welding axe 51 via a horizontal sliding guide 42 in order to bring the cut surfaces of the profile strands into contact with the effective heated surfaces of the welding axe 51. After the cut surfaces have melted in the required manner, the welding axe 51 is moved back to the rest position by moving the lifting rod 72 so that the cut surfaces can be brought into a corner joint connection with the horizontal movement of the holders 40, in which the melted Sennit surfaces weld together. After the welded connection thus produced has cooled, the holders 40 are opened and the connected profile strands removed.

When the welding axe 51 moves downwards, the locking blade 65 again engages with the locking pin 66, whereby the locking between the pair of cutting blades 61 and the welding axe 51 is restored and is ready for a new working stroke.

Fig. 3 illustrates the working position of the cutting blade pair 61. It can be seen that the two &igr;

Cutting blades 62 are guided directly along the end faces 41, so that the profile strands are cut off flush with the end faces 41. In Fig. 3, for better illustration, a cover of the holder 40 shown in the foreground is pivoted away so that a profiled groove 11 for receiving a profile strand becomes visible.

Furthermore, Fig. 3 shows, using the example of the holder 40' shown on the left, that the cutting blades 62 each interact with an abutment 43, which prevents the relevant protruding profile strand from moving upwards. In the working position of the cutting blades 62 shown, they are arranged in advance of the welding axe 51.

Fig. 4 shows the working position of the welding axe 51 frontally between the end faces 41 of the holders 40, after the pair of cutting blades 61 has been retracted.

As can be seen from Figures 3 and 4, the welding axe 51 is provided with a Teflon coating 26 on both sides, which can be easily replaced in the event of wear or if material residues should adhere. Since the welding axe 51 is relatively large in volume _- in order to accommodate the electric heating device on the one hand and to serve as a heat buffer on the other hand - the free end can be provided with a rounded section »a which

Attaching the Teflon coating 26 in one piece on both sides is made easier.

If profile strands are to be processed that cannot be melted or connected to one another by melting, the welding hatchet 51 can be replaced by an application device for adhesives and/or solvents, with which a reliable connection can be made. The individual work steps correspond accordingly to the steps described in connection with the welding hatchet 51.

In Fig. 5, the two brackets 40 are shown in a first position in which the two end faces 41 are arranged at a distance from one another in a parallel alignment. The brackets 40 themselves are arranged at an angle with respect to their longitudinal axes, which run parallel to the grooves 11, which corresponds to the corner joint angle. The figure shows that the sliding guide 42 consists of two guide rails 3, 4, which are held in end pieces 9, 10, which are intended for fastening to the worktop (Fig. 1).

On the guide rails 3,4 there are guide carriages 46,47, which carry the brackets 40 on their upper side. These each consist of a lower part 48 with the profiled grooves 11 and a hinged cover 49.

For this purpose, the guide carriages 46, 47 can be provided, for example, as shown in Fig. 7, with recesses 31 into which the lower parts 48 can be inserted and secured with the aid of fastening means (not shown).

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can be fixed. The grooves 11 are adapted with their bottom surface to the cross-sectional shape of the profiles to be processed. After a profile strand has been inserted into the grooves 11, these are closed by the covers 49, which are pivotally connected to the associated lower part 48 via a joint 17, for example in the manner shown in Fig.5.

The end faces 41 are arranged at a right angle to the longitudinal axis of the guide rails 3,4, so that they can be brought into contact with one another by moving the guide carriages 46,47.

When the welding device is in operation, these known lower parts 48 and covers 49 are initially held with the end faces 41 at a predetermined distance from one another, whereupon the profile strands are inserted into the grooves 11 and the covers 49 are closed in order to carry out the cutting and welding process described above.

Since many types of plastic profiles are very soft, there is a risk during the cutting process that the ends of the plastic profiles protruding from the mold halves will be deformed during the cutting process and bent in the direction of movement of the knife, so that no perfectly flat cutting edge is produced and the perfect welding of these cutting edges is difficult.

In order to prevent this upward bending or deformation of the plastic profiles, adjacent to the end faces 41 are provided with the elastically pre-stressed abutments 13 designed as sliders, which in the embodiment shown are slidably held in recesses f4 in the covers 49, which enables a knife to be moved from bottom to top according to

Fig. 1 assumes. Of course, it would be equally possible to arrange the abutments in the lower parts 48 if the direction of movement of the knife in Fig. 1 ran from top to bottom. In this case, however, it would possibly be necessary to form a surface of these abutments with a profile corresponding to the groove 11.

As can be further seen from Fig. 5, the abutments 13 have transverse grooves 15 near their end which protrudes beyond the end faces 41 in the free state, into which the cutting edges of the pair of cutting blades can enter during the cutting process. These transverse grooves can preferably accommodate the knife with little play, so that on the one hand the free end of the sections of the profile strands protruding beyond the end faces 41 are securely supported and on the other hand the strands can be cut through without hindrance.

Due to the elastic pre-tensioning with the help of compression springs z1, these can be pushed back into the covers 49 when they are brought to the welding axe 51 and when the guide carriages 46, 47 are moved together into the corner joint position, as shown in Fig. 6. Here, the holders 40 are shown in the closed state in the corner joint position.

The compression springs 21 are arranged in blind holes in the recesses 14. A fastening screw 20, which has an enlarged head, extends through countersunk oblong holes in the abutments 13 into the covers 49, so that the abutments 13 are slidably guided in the recesses 14 and, under the action of the pre-tensioning spring 21, protrude over the end faces 41 of the associated lower parts 48 and the covers 49 in the unloaded state.

In order to be able to precisely determine the movement or the respective end positions of the guide carriages 46 and thus of the lower parts 48, stop devices 34, 35 are attached to the guide carriages 46, 47, which are adjustable in order to limit both the position of the guide carriages 46 in the first position and the maximum movement of the end faces 43 in the second position, in which they form the corner joint, so that a weld bead of a predetermined thickness can be formed between the melted cut edges.

As can be seen in particular from Fig. 6, the stop devices 34 limit the movement of the two guide carriages 46, 47 towards each other, while the stop devices 35 limit the movement of the guide carriages 46, 47 away from each other.

In the embodiment according to Fig. 7, other devices are provided for limiting the movement of the guide carriages 46,47. These devices consist on the one hand of a pre-tensioning device in the form of a spring 38, which is arranged between the left end piece 9 and one guide carriage 46 and elastically pre-tensions this guide carriage over a short stroke in the direction of the other guide carriage 47. This stroke is in turn limited by the stop devices 34.

The movement of the other guide carriage 47 away from the first-mentioned guide carriage 46 is in turn limited by the stop devices 35, so that when the mold halves are fastened to the guide carriage 46, 47, an exactly definable distance between the end faces 41 results.

so that the knife can be inserted between these end faces.

One guide carriage 47 also has a locking device that interacts with an annular groove 30 in the guide rail 3. Although many embodiments of such a locking device, which causes a locking between the relevant guide carriage 47 and the guide rails 3, 4, are well known to those skilled in the art, a special, only indicated embodiment is explained in more detail here. This embodiment consists of a leaf spring 36 that is attached flush with the surface in the recess 31, with the free end of the leaf spring 36 being arranged above the guide rail 3. Below this free end of the leaf spring 36 there is a locking pin (not shown) that extends through a hole in the guide carriage 47 on the underside of the leaf spring to the guide rail 3. The locking pin biases the leaf spring 36 upwards in the non-locked state. Approximately in the middle area of the leaf spring 36, a locking pin 37 engages, which in the assembled state is inserted through a hole in the lower part

48 and at the top below the lid

49 protrudes. When the lid is closed, the locking pin 37 is pushed back downwards, whereby the middle of the leaf spring 36 is bent and the locking pin at the free end of the leaf spring 36 is pre-tensioned against the guide rail 3 (Fig. 7).

If the right guide carriage 47 is moved to the left as shown in Fig. 7, the end faces 41 of the holders 40 come into contact with one another, whereby one guide carriage 46 is moved to the left over a certain distance against the action of its pre-tensioning spring 38 until the locking pin engages in the annular groove 30 of the guide rail 3. In this state, movement of the guide carriages 46, 47 and

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so that the lower part 48 is no longer possible until the cover 49 is opened and the locking device is released.

In this way, it is reliably prevented that the guide carriages 46, 47 can be moved apart again after the welding process before at least the cover plate 49 of one of the lower parts has been opened. Otherwise, there would be a risk of the welded joint that had just been made tearing open.

Claims (14)

1. Device for producing a corner joint between two plastic profile strands, for example for window or door seals, with two brackets arranged on a 3-round frame for holding the strands, the brackets each having a front side angled to their longitudinal axis at half a corner angle, with a guide device by means of which the two brackets can be moved relative to one another between a first position in which the two brackets are at a predetermined distance and a second position in which the two brackets are in a corner joint, and with an electrically heatable cutting and welding device for separating and melting the profile strands flush with the front sides of the brackets, the cutting and welding device being arranged in the first position of the bracket so as to be movable between a working position in front of the front sides of the brackets and a rest position offset next to the front sides of the brackets, characterized , that the cutting and welding device consists of a heatable pair of cutting blades (61) and a separate conditioning device (50), and that an adjusting device is present with which the conditioning device (50) can be moved from the respective rest position to the working position and back with a time delay after the pair of cutting blades (61). 2. Device according to claim 1, characterized in that the conditioning device (50) consists of an electrically heated welding axe (51). 3. Device according to claim 1, characterized in that the pair of cutting blades (61) and the welding axe (51) are each heated independently of one another. 4. Device according to claim 1, characterized in that the conditioning device (50) consists of a separate application device for adhesives and/or solvents. 5. Device according to one of the preceding claims, characterized in that the guide device consists of a rail guide in which the two holders (40) are arranged displaceably relative to one another while maintaining a parallel alignment of their two end faces. 6. Device according to one of the preceding claims, characterized in that a positive control is provided with which the pair of cutting blades (61) is moved from its working position to its rest position. 7. Device according to claim 6,
characterized in that the adjusting device comprises a lifting rod (72) on which the pair of cutting blades (61) is arranged so as to be deflectable in the lifting direction under the action of a return spring (69) and is in engagement with a stroke-dependent locking device (64). 8. Device according to one of the preceding claims, characterized in that the cutting axe (51) or the application device is rigidly connected to the lifting rod (72), and that the pair of cutting blades (61) in the locked state projects beyond the welding axe (Si) or the application device and in the unlocked state is retracted in the lifting direction behind the welding axe (51) or the application device. 9- Device according to one of the preceding claims, characterized in that 6&aacgr;& the holders (40) each consist of a lower part (48) which is provided on its upper side with a · - 20 - sectional shape of the profile strands to be cut, and a hinged cover (49) which, when closed, holds the relevant profile strand in the groove (11), and that abutments (13) for the pair of cutting blades (61) projecting over the end faces (41) are provided, which are displaceably attached to the ui i..»....-- / &agr;&eegr;&ngr;&tgr;——&agr;. .. .: .. .&ogr; jn — i ~. .:—— i irax Lei uii^cn \ i\jt ijcriavjci i_ o-liivj, uau oj.cr ± ti cmc £.u the end faces (41) flush with the rest position can be deflected. 10. Device according to claim 9,
characterized in that the abutments (13) are resiliently preloaded against the associated holder (40). 11. Device according to claim 9 or 10, characterized in that the abutments (13) have a transverse groove (15) along the relevant end face (41) for receiving the free end of the pair of cutting blades (61). 12. Device according to one of the preceding claims, characterized in that a locking device is provided with which the two holders (40) are releasably locked in the corner joint position. 13. Device according to claim 12 _r
characterized in that the locking device has an actuating device which is connected to a cover (49) of the holders (40) in such a way that the locking device is unlocked when the cover (49) is opened. * φ 44*· · • · Il · * 3 * - 21 - 14. Device according to one of the preceding claims, characterized in that the two holders (40) are resiliently prestressed against each other in the corner joint position.