EP0057465B1 - Handgun mixer - Google Patents

Abstract

1. A hand mixing gun for the simultaneous extrusion of two low to highly viscous liquids out of a cartridge device containing two liquids separately, in which cartridge device a discharge piston (2) is displaceable for each liquid, with a receiver for the cartridge device, a mixing tube (4) to which the outlets of the cartridge device can be connected and which has an outlet nozzle (6) for the mixed liquids, two piston rods (3) which can be pushed into the cartridge device from the side opposite to the outlets of the cartridge device to push the discharge pistons (2) forwards and a drive motor (9) to move the piston rods (3), wherein the cartridge receiver is adapted to store two cartridges side by side, characterized in that a change-speed gear (8) is provided, which permits the drive of the two discharge pistons (2) at feed speeds, the ratio of which to one another can be preset in order to produce a desired mixing proportion of the two liquids.

Description

The invention relates to a manual mixing gun for simultaneously squeezing two liquids according to the preamble of claim 1, which is known from DE-A-2 537 022.

Two-component compounds, such as adhesives, sealants, joint fillers, etc., are often used in construction, assembly, etc. and must be mixed with one another beforehand in a more or less precise mixing ratio and then applied.

Since the mixed, mostly quite viscous liquids often set or harden soon after mixing, it is advisable to carry out the mixing only when applying.

So z. B. a hand-held mixing gun for two-component compositions is known, in which two coaxially nested cylinders, each filled with one of the components, form a cartridge that can be inserted into the mixing gun, which has a mixing tube for the two components . At the other end of the pistol there is a handle that is connected to two pistons by means of two piston rods, each of which plunges into one of the two component containers and is advanced at the same speed.

The particular advantage of this gun is that the two components are mixed with one another immediately before application, and that an exact mixing ratio can be maintained due to the container geometry.

A disadvantage of the known pistol is the fact that a separate, suitable cartridge must be produced for each mixing ratio. These coupling cartridges are very complex to manufacture and also difficult to fill. This is a major disadvantage as the cartridges are used only once.

These disadvantages are remedied in part by another known processing gun, in which the one component present in a tube in the cartridge can be pressed out together with the other component by means of compressed air, after which the mixing takes place in a mixing tube by means of a motor-driven stirrer.

However, the known processing pistol is not able to mix components which have been filled into cartridges in a respectively adapted, variable mixing ratio.

Based on this prior art, the invention provides a hand-held syringe according to the preamble of claim 1, which is further developed in a simple manner in that it can deliver mixed pastes mixed from two standard cartridges filled with different components, the component ratio of each, without structural changes is adjustable and is therefore suitable for processing different two-component materials.

This is achieved by the features of claim 1.

Since the drive device for the feed pistons drives them at the same or different feed speeds, the ratio of the feed speeds being adjustable and precisely observable, it is sufficient to insert the cartridges with the two components into the receptacle, to connect them to the mixing tube and then to drive the drive device accordingly Set the desired mixing ratio so that the respective liquid exits the outlet of the cartridges at exactly the right throughput into the mixing tube, in which the mixing then takes place.

In practice, it can be expedient to always drive one of the two piston rods at a reference speed and, in contrast, to advance the other piston rod correspondingly faster or slower.

According to one embodiment of the invention, it is advantageous to design the paste containers to be of the same size, which considerably simplifies production. Since the mixing ratios for two-component pastes are usually between 1: 1 and 10: 1, it is possible to achieve correspondingly different feed speeds with relatively little technical effort.

The cartridges are advantageously cartridges supplied with the respective paste for single use, which only need to be inserted into the manual mixing gun.

In order to improve the universal use of the manual mixing gun, to reduce the time required for cleaning and to facilitate the changeover to other components, the extension pistons can be designed as a closure for the paste cartridges, in which case the piston rods only rest against the extension pistons. Since the ejection pistons remain with the cartridges and may be designed as disposable units with them, any other possible contamination of the syringe on the drive side is eliminated.

According to one embodiment of the invention, in order to achieve a particularly simple arrangement, it is advantageous that the drive motor - possibly via an intermediate gear - drives the change gear, which actuates the piston rods via two outputs. Since both drives are fed by the same drive and the ratio of the feed speeds of the piston rods is fixed, this ratio is maintained even if the speed of the drive motor decreases as a result of flow resistance or the like.

The change gearbox is best one with little or no slip. It can at be designed as a change gear transmission, for example. In order to simplify the operation of the syringe according to the invention, it is proposed according to the invention to use a switchable gear change transmission, a continuously variable adjustment transmission (so-called PIV transmission) or a transmission with transmission elements which are interchangeable with others in order to achieve a different transmission ratio.

In principle, it is possible to act on the piston rods by means of drivers, chain hoists or push levers; According to further refinements of the invention, however, it is advantageous to design the piston rods as toothed racks or threaded rods, the piston rods then in turn already forming transmission elements of the change gear.

Since the feed ratio of the two piston rods is independent of the speed of the drive motor, it is advantageous according to a further embodiment of the invention that the drive motor is a motor with a variable speed, so that the throughput of the two-component paste through the outlet nozzle of the syringe can be easily adapted to the respective working conditions, so that an even more universal usability of the syringe is achieved.

A motor of any speed can be used as the drive motor, where appropriate a reduction gear ensures that a speed suitable for the gearbox or the toughness of the pastes used is achieved. If necessary, an adjustment gear can also be assigned to the countershaft in order to achieve the above-mentioned advantageous speed change when using a motor with a substantially constant speed.

In the sense of the simplification required by the task, it is proposed in a further embodiment of the invention that the drive motor is a compressed air motor, since such a motor delivers the high drive power required for pressing out viscous pastes or liquids with a relatively small size. In addition, a quantity control valve for controlling the speed can be assigned to the compressed air motor.

If, when using the syringe, one of the two pistons has reached the end of its path of movement, then this piston can be moved back by reversing the direction of rotation of the drive motor, if necessary by means of a reversing gear, in order to enable the cartridges to be replaced. Because of the fixed feed assignment of the two piston rods, however, in this case the other of the two pistons or at least the piston rod assigned to them moves back to its starting position. Since in this case one of the two cartridges is still largely filled in the case of large mixing ratios, it is proposed according to a further embodiment of the invention that at least one piston rod can be released from engagement with the drive device and can be withdrawn independently of this for replacing a paste cartridge. In this case, one of the pistons, which is located in the not yet empty cartridge, remains in its position, while the piston rod assigned to the other piston is released from engagement with the associated gearbox and is freely withdrawn. After replacing the empty cartridge, the piston rod is placed back on the piston head of the relevant cartridge and the drive engagement between the piston rod and the associated gear is restored.

If the engagement of both piston rods can be released, then material supplied in cartridges can be completely used up to the rest during a longer working time, regardless of the filling quantities of the cartridges and the mixing ratio set in each case.

For certain components that are easy to mix, it may be sufficient to mix the pastes in the mixing tube only at an angle. If components which are more difficult to mix are also to be used, it is proposed according to a further embodiment of the invention that the mixing tube in its section adjacent to the outlet nozzle and through which both pastes flow, has a helical mixing spindle for better mixing, which can be attached stationary in the mixing tube and for which ensures reliable mixing of the two component pastes. For particularly good mixing, it is advantageous to use a mixing spindle driven to rotate, which is preferably driven by its own motor, in particular a compressed air motor.

In order to avoid, in particular at the higher pressing speeds mentioned, that one of the components escapes to a leak and thus not only leads to contamination of the syringe, but also to an impairment of the mixing ratio, it is proposed according to a further embodiment of the invention that the Cartridges each have a threaded connector at their outlet opening, which is screwed to the associated connection of the mixing tube, in order thus to produce a reliable seal.

The screw connection can be done, for example, by means of a union nut; According to a further embodiment of the invention, the connections of the mixing tube can also have an internal thread into which the threaded connector of the cartridge is screwed. These refinements of the invention contribute to the structural simplification, since it may be sufficient if the only effective holding of the paste cartridges in the pistol is produced by the threaded connection piece in addition to the holding effect exerted by the piston rod by the engagement with the feed piston which can be screwed into the nut thread of the mixing tube or the union nut easily and quickly by hand. Especially when using viscous pastes, it is advantageous to secure the paste cartridges at the opposite end against lateral deflection.

According to a further embodiment of the invention, the mixing tube is designed as a disposable injection-molded part, which can be easily removed from the syringe when both paste cartridges are unscrewed. This eliminates the need for costly cleaning and, if necessary, the processing of pastes that set in a relatively short time is possible: if the setting time is accidentally exceeded during a break from work, then only the mixing tube needs to be replaced in order to continue the work without major ones Allow interruption. Especially when using a driven mixing spindle, it is advantageous that the receiving part of the mixing tube z. B. is releasably attached to the remaining part with a bayonet lock in order to enable easy cleaning or, if necessary, the replacement of as few parts as possible.

For better handling, the mixing syringe according to the invention preferably has a handle to which a trigger for the drive motor for the feed pistons and, if appropriate, the motor for the rotatable mixing spindle is assigned, preferably in the manner of a pistol grip, on which a trigger is the trigger for the motor or forms the motors.

According to a further embodiment of the invention, the cartridge receptacle has a holding plate arranged transversely to the cartridges, in which guide openings are preferably formed, which grip around the ends of the cartridges and are suitable for supporting them against transverse deflections and thus also for the use of highly viscous pastes which considerable forces have to be applied for pressing.

If a cartridge is to be replaced during use, the mixing tube remains in place and it is therefore necessary to design the drive in such a way that it permits the removal and insertion of a cartridge through the respective guide opening from behind. For this purpose, the drive motor is advantageously mounted in front of the holding plate, preferably between the two cartridges.

Insofar as a manual transmission is used as a change-speed transmission, this allows the feed-speed ratio of the two cartridge pistons to be changed rapidly; however, since the mixing ratio is often longer for a longer period of time, the particularly rapid switching is less important in this case. It is therefore proposed according to a further embodiment of the invention that the change gear has transmission elements which are interchangeable with those with different transmission ratios. Such transmission elements can be carried in a suitable tool case and selected accordingly before starting extensive work. The gear ratios already given can be produced by combining relatively fewer transmission elements.

According to a further embodiment of the invention, it is particularly advantageous if the drive pairing is selected as the transmission element, which consists of a threaded shell and a threaded spindle, which in turn forms the piston rod. Changing the gear ratio is achieved by using a threaded spindle and a drive nut with a different thread pitch.

This drive nut is preferably fastened centrally in a gearwheel, which has the same pitch and number of teeth. In the manual mixing gun according to the invention, two such gearwheels are attached, both of which are in engagement with an associated pinion and thus rotate in the same direction. The two gearwheels with their associated threaded bushings and threaded spindles can be exchanged for one another.

Each such gear is preferably rotatably mounted in a releasably attached to the back of the holding plate gear carrier, wherein the gear carrier is advantageously pivoted about a transverse axis such that it can be attached to the holding plate with both its front and back. The particular advantage of this design is that when the cartridge is empty, when the associated threaded rod that forms the piston rod is fully extended, it does not need to be turned back completely after inserting the new, full cartridge, but only has to be turned over together with the gear carrier got to; it is then sufficient to set the other end of the threaded spindle, which then protrudes in the direction of the cartridge, only briefly in order to make the manual mixing gun according to the invention ready for operation again after the gear carrier has been put on again.

In order to avoid inaccuracies, the length of the threaded spindle is dimensioned such that it is in exact engagement with the piston of the cartridge again after removing the gear carrier, changing the cartridge, pivoting the gear carrier with the threaded spindle and reattaching the gear carrier.

This is ensured by suitable measures that the threaded spindle essentially always remains untwisted, since a rotation of the threaded spindle relative to the cartridge falsifies the selected translation ratio defined between the threaded bushing and the threaded spindle by the thread pitch relationship would occur.

The gear carrier is preferably formed from two hollow cylindrical carrier rings of identical design, which are axially immovable but rotatably fastened to one another via the gear and the threaded bushing.

The end face of each carrier ring is preferably equipped with one or more, preferably two undercut arch grooves, which engage in a head-like counter-formation to form a bayonet catch, which is preferably attached to the holding plate in the form of a screw.

If a large number of gear carriers are used to allow a very large number of mixing ratios, then it can also be advantageous to provide the arc grooves in the holding plate and to provide the counter-projections which are easier and cheaper to install on the respective carrier ring.

When using such carrier rings, which are provided on the outside with a handle, for. B. a cord, the root diameter of the associated gear is advantageously chosen larger than the outer diameter of the carrier ring, so that the mounting or turning and replacing the respective gear carrier is possible without this coming into engagement with the drive pinion.

As already noted above, the mixing spindle can advantageously also be designed to be rotatable, and in turn preferably be connected to its own rotary drive, which is preferably designed as a compressed air motor and is fed via an air line that is common or separate with the drive motor for the piston feed.

The rotating spindle is preferably mounted in a tube section arranged on the front of the mixing tube, which for cleaning or replacement is optionally also detachably attached to the mixing tube together with the rotating mixing spindle, for example also by means of a bayonet catch. Furthermore, all those parts of the mixing tube which can come into contact with the mixture of the two components to be mixed are easily detachable and can be dismantled or replaced.

• Fig. 1 teilweise im Schnitt das Schema eines Ausführungsbeispiels der erfindungsgemäßen Hand-Mischpistole;
• Fig. 2 die Ansicht eines anderen Ausführungsbeispiels im Schrägbild;
• Fig. 3 die teilweise geschnittene Draufsicht auf die Ausführungsform der Fig. 2;
• Fig. 4 die schematische Darstellung einer Antriebseinrichtung für eine erfindungsgemäße Hand-Mischpistole;
• Fig. eine schematische Draufsicht auf ein weiteres Ausführungsbeispiel der erfindungsgemäßen Hand-Mischpistole;
• Fig. einen Teil-Längsschnitt durch den Antriebsteil des Ausführungsbeispiels der Fig. 5, in vergrößertem Maßstab;
• Fig. 7 eine Teilansicht in Richtung des Pfeiles VII in Fig. 6 und
• Fig.8 8 einen Teil-Längsschnitt durch den Mischteil des Ausführungsbeispiels der Fig. 5, in vergrößertem Maßstab.

The object of the invention is explained in more detail with reference to the exemplary embodiments shown in the schematic drawing; in this shows

• 1 shows, partly in section, the diagram of an exemplary embodiment of the manual mixing gun according to the invention;
• Figure 2 shows the view of another embodiment in the oblique image.
• Fig. 3 is a partially sectioned top view of the embodiment of Fig. 2;
• 4 shows the schematic representation of a drive device for a manual mixing gun according to the invention;
• Fig. A schematic plan view of a further embodiment of the manual mixing gun according to the invention;
• Fig. A partial longitudinal section through the drive part of the embodiment of Figure 5, on an enlarged scale.
• Fig. 7 is a partial view in the direction of arrow VII in Fig. 6 and
• 8 8 is a partial longitudinal section through the mixing part of the embodiment of FIG. 5, on an enlarged scale.

In the figures, the same reference numerals designate the same or functionally identical parts.

In Fig. 1 is a highly schematic, partially sectioned top view of an embodiment of a hand-held mixing gun is shown, the z. B. is suitable for applying a two-component adhesive based on polyurethane or a two-component polysulfide sealant.

Two parallel, circular cylindrical commercially available paste cartridges 1 are screwed with their front, each open end into corresponding connections of a mixing tube 4. The two connections merge symmetrically into a tube section arranged centrally with respect to the two cartridges 1, within which a mixing spindle 5 is fixedly attached in this exemplary embodiment. The mixing spindle 5 here consists of successive, alternating opposing, helical partition walls and brings about an intimate mixing of the two component pastes, each flowing out of one of the cartridges 1. The mixing tube 4 ends in an outlet nozzle 6.

The rear ends of the plastic cartridges 1 are open.

In each of the cartridges 1, an ejection piston 2 is slidably and sealingly attached in a known manner. On its side facing the rear end of the paste container 1, a rotatable and displaceable piston rod 3, which is arranged coaxially with the paste container 1, is supported on the piston 2.

Both piston rods 3 pass through a transmission 8, at the rear end of which a motor 9 is attached.

Piston rods 3, gear 8 and motor 9 together form a drive device 7, which is attached together with the paste containers 1 on a common holder (not shown). The two piston rods 3, each designed as a threaded spindle, are in positive engagement with transmission parts in the interior of the transmission, the transmission ratio between the two transmission parts, each associated with one of the piston rods 3, being variable by means of an adjusting head 15.

An exemplary embodiment of a hand-held mixing gun is shown in FIG. The basic principle is the same as that shown in FIG. 1.

A receptacle or bracket 10, which has the drive 7 on its back and on its lower side carries a pistol grip 11, is provided with two trough-shaped recesses, into each of which a commercially available plastic cartridge 1 can be inserted. The cartridges 1 have at their mouth ends a threaded connector 16 which can be screwed sealingly into an internal thread 17 of the mixing tube 4. The mixing tube 4 is inserted from the front into slots in a perforated end wall of the holder 10 and is only held by the screw connection to the cartridges 1.

The two, in each case identical cartridges each have a piston 2 in their interior, against which the corresponding plate-shaped, front end of the piston rods 3 is supported when in use.

The transmission 8 has on its upper side a shift lever 15 for selecting the feed ratio or the mixing ratio for the two paste components. It is six steps and z. B. designed for the ratios 10/1, 7/1, 5/1, 3/1, 2/1 and 1/1 between the feed speeds of the piston rods.

At the rear of the transmission 8, an air motor 9 is attached centrally between the two piston rods 3, which is connected via an air line 13 to an air metering valve (not shown), which is attached to the inside of the pistol grip 11. A trigger 14 is set up to actuate the air metering valve.

The second connection of the valve is connected to an air hose 12.

Fig. 3 shows in section the two paste cartridges 1, as they are inserted in the holder 10 and are screwed to the internal threads 17 of the mixing tube 4. As can be seen, the two paste cartridges 1 are each filled, since the respective piston 2 is in its outermost, rear position.

Within the mixing tube 4 there is a mixing spindle 5, which is designed similarly to the embodiment shown in FIG. 1.

It can be seen that after the two paste cartridges 1 have been removed, the mixing tube 4 can also be easily removed.

The mixing tube 4 is designed as a disposable plastic part.

The gear 8 can, for. B. be designed as the pull wedge gear 18 shown in FIG. 4 with a drive part 19 and an output part 20. The output part 20 carries a set of stepped gears, which are rotatably connected to a shaft 21. The drive part 19 carries a complementary set of gear wheels which can be brought into rotational engagement with the associated shaft 21 individually in a known manner by means of a pulling wedge. To change the engagement of the pull wedge, a shift sleeve 22 is provided, which is displaceable via a linkage (not shown).

The shaft 21 is driven by a worm drive 22, which in turn is connected to the drive motor (not shown). A pinion 23 is fixedly connected to the shaft 21 and drives via a piston rod 3a designed as a toothed rack. The other piston rod 3b is driven with the interposition of an intermediate pinion 25 by the driven part 20 of the pull wedge gear 18.

It is readily apparent that a change in the gear ratio in the pull wedge gear also entails a corresponding change in the feed of the two piston rods 3a, 3b.

Each of the two piston rods 3a, 3b designed as a toothed rack is held in engagement with the associated drive pinion 23 or 25 by means of a pressure roller 26a or 26b. The pressure roller 26a or 26b can be locked in the position shown in the drawing and, after releasing the locking, can be pivoted away from the associated piston rod in the direction of the arrow shown. In the pivoted-away position of the respective part 26a or 26b, the associated piston rod 3a or 3b can be lifted out of engagement with the associated drive pinion 23, 25 and retracted individually, without the gear engagement of the other piston rod needing to be released or a change in the Gear ratio is necessary.

If, when using the mixing syringe shown, one of the two paste cartridges 1 is empty while the other still contains filling, then the pressure roller 26a, 26b of that piston rod 3a, 3b, which is assigned to the empty cartridge, is released from the catch and the corresponding piston rod becomes lifted out of engagement with the drive pinion 23, 25 and withdrawn until the empty paste cartridge 1 can be removed. After inserting a new paste cartridge 1, the corresponding piston rod is pushed forward again as far as it will go with the piston 2 and the associated pressure roller 26a, 26b is locked again, whereby the piston rod is pressed into engagement with the associated drive pinion 23, 25. The work can now continue without disturbing the mixing ratio.

5 schematically shows another embodiment of the hand-held mixing gun in a top view.

This hand-held mixing gun has a holder 10, similar to the embodiment in FIG. 2, to which (not shown in FIG. 5) a handle with a trigger is attached.

In contrast to the embodiment of FIG. 2, in the embodiment shown in FIG. 5, the two cartridges 1 are arranged at a greater distance from one another in such a way that the compressed air motor 9 can be arranged between them.

At the front end of the hand-held mixing gun shown, a mixing pipe 4 is attached, which opens into a pipe socket 4 ', in which, as can be seen more clearly from FIG. 1, the mixing spindle 5 is arranged. The mixing spindle In contrast to the previous exemplary embodiment, 5 is designed to be rotatable and is seated on the shaft of a compressed air motor 29, which is mounted in alignment with the compressed air motor 9 between the two cartridges 1 on the side of the mixing tube 4 facing away from the connecting piece 4 '.

The outlet nozzle 6 is attached to the front end of the nozzle 4 '.

The mixing tube 4, on the one hand, and / or the connecting piece 4 'together with the outlet nozzle 6, in each case or together with the mixing spindle 5, form an exchangeable or disposable part which, by means of a suitable connection, for example a bayonet catch, on the holder 10 or on the mixing tube 4 is attached. This makes it easy to remove and thus either disassemble and clean or replace those parts which come into contact with the reactive mixture of the two pastes, which are each housed separately in the cartridges 1.

In the area of the rear ends of the cartridges 1, a holding plate 29 is attached transversely to the latter, which is firmly connected to the holder 10 and carries the drive motor 9 on its side facing the mixing tube 4, the shaft 30 of which penetrates the holding plate 27 and beyond it on it free end carries a pinion 31.

With this pinion 31 are two gears 32 in engagement, each of which is arranged coaxially to each of the cartridges 1 and rotatably mounted in a gear carrier 28 which is removably attached to the holding plate 27. The drive will be explained in more detail with reference to FIGS. 6 and 7.

5, the air line 13 for the compressed air motor 9 and a further air line 13 'for the compressed air motor 29 can be seen. Both air lines 13, 13 'can advantageously open together in a (not shown) compressed air supply pipe.

The gearwheel carrier 28, the gearwheels 32, the piston rods 3, which are arranged coaxially to these and are designed as threaded spindles, and the pinion 31 form parts of the transmission 8, which is shown in more detail in FIG. 6.

As can be seen from FIG. 6, a threaded bushing 33 is fastened in the center of each gear wheel 32 and coaxially thereto, said threaded bushing being in threaded engagement with the threaded spindle 3, which forms the piston rod.

The gearwheel carrier 28 is formed from two identical, oppositely aligned carrier rings 28a, 28b, which are each corded on the outside and have a diameter which is smaller than the tooth base circle diameter of the respective gearwheel 32.

Each carrier ring is designed as a hollow cylinder, the bottom of which is drilled through in such a way that the threaded bushing 30, with its respective cylindrical outside, can penetrate the two bottoms of the carrier rings 28a, 28b with guidance but rotatably.

The outer surface of the threaded bushing 33 has a recess, in which a spring ring is attached in such a way that it just projects above the bottom of the respective carrier ring 28a, 28b in such a way that the rotation of the threaded bushing 33 relative to the carrier rings 28a, 28b is not hindered, but the axial play of the threaded bush 33 is limited to a minimum in this regard.

The inner diameter of the carrier rings 28a, 28b essentially corresponds to the outer diameter of the cartridges 1 such that they can be inserted into the carrier rings.

On the respective end face, the carrier rings 28a, 28b each have two opposing arc grooves 34, which extend over a circular arc of approximately 90 °, each of which opens opposite one another into a circular opening 35, the diameter of which is greater than the width of the arc groove 34.

As can be clearly seen from FIG. 6, the arc groove 34 is formed with a T-shaped, undercut cross-sectional profile.

The holding plate 27 has a guide opening 36 in alignment with each of the cartridges 1, the diameter of which is dimensioned to match the outer diameter of the cartridge so that it can be easily inserted through the respective guide opening 36.

On both sides of the guide opening 36 and the two openings or widenings 35 of the arc grooves 34, a threaded bore is arranged in the holding plate 27, into which a screw is screwed in from the side of the gear carrier 28 and has a cylindrical head with such a dimension, that the support ring 28a or 28b with the widenings 35 of its arc grooves 34 can be placed over the heads of the screws 37 and then pivoted through 90 °, the heads of the screws 37 engaging behind the arc groove profile, so that the arc grooves 34 and the screws 37 together form a bayonet catch.

As already mentioned above, the threaded bushing 33 and the gear wheel 32 are rigidly connected to one another and rotatably mounted relative to the carrier rings 28a, 28b, a material being selected for these carrier rings 28a, 28b which is assigned to the material of the threaded bushing 33 and the gear wheel 32 results in a self-lubricating effect, so that the gear 32 and the threaded bushing 33 are rotatably mounted maintenance-free within the carrier rings 28a, 28b.

The inner opening of the carrier ring 28a and the guide opening 36 of the holding plate 27 are each aligned and together form a receptacle for the rear end of the cartridge 36.

By slightly chamfering the arc groove 34 in the axial direction, when the gear carrier 28 is tightened on the holding plate 27, an axial clamping movement can take place, by means of which the front end of the cartridge 1 is pressed firmly against the mixing tube 4 and also si It is ensured that the gear carrier 28 does not loosen during use of the mixing gun.

Each gear carrier 28 has a threaded bushing 33 and a feed rod 3 with the same thread pitch, the thread pitch being different for different gear carriers 28. Since these gear carriers 28 are readily interchangeable, a large number of mixing ratios can be combined by means of a series of gear carriers with associated feed rods of different thread pitch.

When two cartridges are inserted, they are pushed through the guide openings 36 and sealed with their front side on the mixing tube 4. The appropriate gear carrier 28 is then selected and fitted in accordance with the desired mixing ratio. In these gear carriers, the piston rod 3 is in its one end position and comes into engagement with the piston located in the interior of the cartridge 1, the rotation of the piston rod relative to the piston preferably by positive engagement and the rotation of the piston relative to the cartridge wall by the force fit between these parts is prevented. If the frictional connection is not sufficient, the piston rods can each have an axial groove in addition to the thread, into which, for example, a nose of a yoke placed from behind on the free piston rod ends engages, which protrudes from a corresponding inner bore of the yoke, which protrudes from the piston rod is enforced.

If one of the two cartridges is emptied, the corresponding gear carrier 28 is removed, the empty cartridge is pulled out to the rear to the guide opening 36, the new cartridge is inserted, the gear carrier is turned over and replaced. The length of the piston rod 3 is accordingly dimensioned such that when it is fully extended into the cartridge at one end, it protrudes with its other end just beyond the other end of the gear carrier 28 so that it turns when the gear carrier is turned over and thus the piston rod 3 also comes into exact engagement with the piston of a new, filled cartridge.

Claims (14)

1. A hand mixing gun for the simultaneous extrusion of two low to highly viscous liquids out of a cartridge device containing two liquids separately, in which cartridge device a discharge piston (2) is displaceable for each liquid, with a receiver for the cartridge device, a mixing tube (4) to which the outlets of the cartridge device can be connected and which has an outlet nozzle (6) for the mixed liquids, two piston rods (3) which can be pushed into the cartridge device from the side opposite to the outlets of the cartridge device to push the discharge pistons (2) forwards and a drive motor (9) to move the piston rods (3), wherein the cartridge receiver is adapted to store two cartridges side by side, characterized in that a change-speed gear (8) is provided, which permits the drive of the two discharge pistons (2) at feed speeds, the ratio of which to one another can be preset in order to produce a desired mixing proportion of the two liquids.

2. A gun as claimed in claim 1, characterized in that the drive motor drives - possibly through an intermediate gear - the change-speed gear, which displaces the piston rods (3) through two outputs and wherein the ratio of the two piston- rod speeds to one another is variable.

3. A gun as claimed in claim 1 or 2, characterized in that the gear (8) is a wheel-type gear comprising a plurality of change-speed elements or shift stages.

4. A gun as claimed in one of the claims 1 to 3, characterized in that the piston rods (3) are threaded spindles, are guided non-rotatably and can be actuated by drive nuts (33) which are axially located and can be driven.

5. A gun as claimed in one of the claims 1 to 4, characterized in that the engagement of at least one piston rod (3) with the rest of the drive system (7) is releasable and this piston rod can be pulled back, independently of the rest of the drive, to change a cartridge (1).

6. A gun as claimed in one of the claims 1 to 4, characterized in that the mixing tube (4) has a mixing spindle (5) in its portion adjacent to the outlet nozzle (6) and through which the two liquids flow, for more thorough mixing.

7. A gun as claimed in one of the claims 1 to 6, characterized in that the cartridge receiver (10) has, in the region of the ends of the cartridges (1) opposite to the outlets, a holding plate (27) which is disposed transversely to these and on which the motor (9) is mounted between the two cartridges (1) at the side of the holding plate (27) adjacent to these.

8. A gun as claimed in claim 7, characterized in that the holding plate (27) has guide apertures (36) which receive the cartridges (1) in the region of their ends.

9. A gun as claimed in one of the claims 4 to 8, characterized in that a central drive pinion (31) is in engagement with two similar, exchangeable gear-wheels (32) which each carry a threaded bush (3) which is mounted centrally and connected thereto for rotation therewith and which comprises an internal thread fitting the particular external thread of the piston rod (3) constructed in the form of a threaded spindle, the piston rods, for their part, being guided non-rotatably.

10. A gun as claimed in claim 9, characterized in that the gear-wheels (32) are each mounted for rotation in a gear-wheel carrier (28) which is releasably secured to the holding plate (27) and which is constructed symmetrically in relation to the central plane of the gear-wheel (32) and, after being released from its connection to the holding plate (27) and pivoted through 180° about a pivotal axis extending transversely to the gear-wheel axis, can be secured to the holding plate (27) again.

11. A gun as claimed in claim 10, characterized in that the gear-wheel carrier (28) is formed from two carrier rings (28a, 28b) in the form of hollow cylinders which are provided at their outside with a handle and comprise, at their upper end face, engagement slots (34) for a bayonet connection with counter formations (37) on the holding plate (27) and enclose, between their adjacent bottom surfaces, the gear-wheel (32) by means of which they are rotatably connected, and in that the external diameter of the carrier rings (28a, 28b) is smaller than the diameter of the root circle of the gear-wheel (32).

12. A gun as claimed in claim 11, characterized in that the internal diameter of the hollow cylindrical carrier rings (28a, 28b) corresponds to that of the guide aperture (36) and is dimensioned to receive a cartridge (1).

13. A gun as claimed in one of the claims 4 to 12, characterized in that the length of the piston rods (3) is dimensioned in such a manner that when they assume the first end position existing with a completely empty cartridge (1), with their one end, after pivoting of the gear-wheel carrier (28), they assume the second end position afforded with a full cartridge, with their other end.

14. A gun as claimed in one of the claims 1 to 13, characterized in that the mixing spindle (25) is rotatable and is connected to a rotary drive (29).

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