MASTICS DISPENSERThis invention relates to means for dispensing mastic compositions such as sealants, adhesives and the like.
In the building trade, plastic preparations for sealing gaps and joints, and certain adhesives, are generally referred to as "mastic compositions" or "mastics" and are usually supplied contained in rigid tubes having a dispensing nozzle at one end and containing a piston which can be displaced sealingly along the tube towards the nozzle end in the manner of a plunger to expel the mastic from the tube. Known mastic dispensers include a frame adapted to hold the tube so that the plunger disc can be displaced by a spring-loaded thrust member under the control of a manually-operated release trigger. This arrangement is fairly cumbersome, and is not suited to use in confined spaces; furthermore, continuous or extended use is physically tiring on the muscles of the hand.
The object of the present invention is to provide for powered operation of mastic containers of the type described.
According to the invention, apparatus for dispensing a mastic composition from a cylindrical container having a dispensing nozzle at one end thereof and a piston slidable therein to expel mastic composition through the nozzle as the piston advances in use, comprises means for supporting a rotary-output motor in relation to the container and drive means for translating rotary motion into linear motion to impart thrust to the piston via a thrust member, the apparatus also including means for cutting through the wall of the container in a longitudinal direction as the piston is advanced.
The cutting of the container wall creates a passage for the thrust member, thereby enabling the motor, which is preferably electrically-powered, to be supported with its rotary axis displaced to one side of, conveniently parallel to and below, the longitudinal axis of the tube. Such an arrangement minimises the overall length of the mastic container including the inventive apparatus and improves the balance and handling Froperties, compared with mounting the motor co-axially with the container at the distal (with respect to the nozzle) end thereof.
The drive means preferably comprises a screw-threaded rod or mandrel rotatably mounted parallel to the longitudinal axis of the container and carrying a threaded collar member which, on rotation of the rod or mandrel in one direction, will advance and cause forward thrust to be applied to the piston and, on rotation of the rod or mandrel in the other direction, will return along the rod or mandrel in a rearward direction.
The cutting means should be positioned somewhat behind the piston, considered in relation to the direction of advance, so that the wall of the container remains intact until the piston has passed. The motor is preferably mounted with its output drive axis parallel to and spaced laterally from the longitudinal axis of the container and the screw-threaded rod or mandrel is rotatably mounted with its axis of rotation also parallel to the said container axis, the rod or mandrel being located between the container and motor or positioned to one side of the motor. The rod or mandrel may be operatively connected to the motor via a gear train which may include a reduction gear, in order to increase the power available to the thrust member in cutting the container wall and expelling the mastic composition.
Apparatus according to the invention may either be adapted as an attachment for an electric drill motor of the commonly-available type suitable for use by an amateur or "do it yourself" person or, alternatively, be provided as a purpose-built unitary assembly for use by a professional or other person who intends to make extensive use thereof, or to be made available for hire. According to the first arrangement, the handle and body of the drill motor, which should either be of the reversible type unless the connecting gear train includes a reversing gear, provide suitable manual support means for the apparatus, particularly where the motor is carried displaced laterally from the container so that, in use, the container is either above the motor or is displaced to one side thereof.In such an arrangement, the centre of gravity of the apparatus inc lii ding the container and motor acts substantially through the motor, which creates a reasonably balanced assembly for the user. Furthermore, the apparatus is held reasonably close to the nozzle, allowing precision of application readily to be achieved. According to the second arrangement, the housing for the apparatus including the motor can be made to include suitable manual support means according to the general shape, configuration and dimensions of the apparatus.
Embodiments of the invention will now be described by way of example with reference to the accompanying drawings, of which Figure 1 is a diagrammatic side elevation of apparatus suitable for use with an electric drill motor, andFigure 2 is a similar representation of a purpose-built assembly incorporating an electric motor.
Referring to Figure 1, the apparatus consists essentially of a frame 10 which includes an annular shoulder member 11 for receiving the forward end of a mastic container tube 13 and a longitudinal side member 12 including means (not shown) to retain the rearward end of the tube 13. The tube has a nozzle 14 and a piston 15. Mounted beneath the side member for rotational movement in bearings 16, 17 is a threaded rod 18 including a rearwardly-extending plain portion 19 for securing in the chuck of a domestic electric drill motor (not shown). The apparatus also includes means (not shown) for engaging with the drill motor body to hold the apparatus in fixed relationship to the motor body.
A carrier 20 is threadedly mounted on the rod 18; the carrier 20 supports a thrust plunger 21 for engagement with the piston 15 of the tube and the carrier has a sharpened portion 22 formed on its leading edge. The apparatus frame includes a removable end cap 23 to permit removal of the carrier for cleaning, re-sharpening of the portion 22 or replacement of the carrier.
In use, a drill motor equipped with a reversing facility is attached to the engagement means and the chuck of the motor output shaft is secured to the plain portion 19 of the rod 18. If necessary, the drill motor is run in reverse mode to position the carrier at the rear end of the rod 18. A mastic container tube is then located in the frame 10, as illustrated, and the motor run in forwards mode to advance the carrier to cut a passage in the wall of the tube as the thrust plunger applies pressure on the piston 15 to expel the tube contents through the nozzle 14.
Referring to Figure 2, the apparatus is functionally similar, and like parts are indicated by like reference numbers. The apparatus consists essentially of a frame 24 for holding a mastic container tube, integrally formed with a motor housing 25, a handle 26 including a switch 27 for controlling the motor, a gearbox 28, a transfer gear train 29, and a housing for the threaded rod, bearings and the like.
The motor may be mains-powered or battery-powered, batteries may be rechargeable and may be housed in the handle.