GB1087993A - Improvements in or relating to adhesive applying apparatus - Google Patents

Abstract

1,087,993. Coating apparatus. VICKERS Ltd. Sept. 28, 1964 [Oct. 2, 1963], No. 38848/63. Heading B2L. Apparatus for applying adhesive to a workpiece comprises a container, a melting member mounted in said container for melting adhesive placed therein, the melting member having an opening or passage therein through which molten adhesive can flow downwardly to a pump chamber, heating means for heating the melting member and for maintaining adhesive in a molten state in said chamber, the latter being fitted with a pump capable of continuous operation with 'slip' so that during operation, molten adhesive can be forced by the pump from said chamber through a delivery tube to an applicator having control means for controlling the delivery of adhesive from the applicator to the work. In the arrangement shown adhesive 8 in solid or semi-solid state is fed into pre-melt unit 1 where by means of heater 9 and themostatically controlled heating elements 12, 10 it is melted and brought to its normal working temperature. The adhesive flows from unit 1 into receptacle 3 the rate of flow being controlled by cock 15 to maintain the required level. The receptacle 3 comprises a main part 16 provided externally with an electric heating element 17 and lagging 18 and is fitted with a continuously operating pump 23 which forces adhesive through delivery tube 24 to the applicator head, the rate of flow being controlled by cock 28 and/or the speed of pump 23. The applicator head (Fig. 2) consists of relatively movable tubular elements 29, 32, the movement being limited by pin and slot connections 34, the arrangement being such that by means of radial arm 35, slots 36 and 37 can be brought into or out of register thereby to control the delivery of adhesive on to a workpiece. Alternatively the slots may be brought into register by axial movement. The number, size and shape of the outlet apertures may be varied according to the manner in which the adhesive is to be deposited, e.g. as a continuous or broken ribbon and a plurality of applicator heads may be supplied from a single pump said applicators being separately operated to give a desired pattern of adhesive application and operated in a desired sequence with the movement of the workpiece. In a second embodiment, modified apparatus is fitted to a box making machine and sheets, e.g. of double faced corrugated cardboard, to be secured together in the formation of a box are passed over and under the applicator head which applies adhesive to the upper face of the bottom sheet prior to the sheets being brought together between pressure rollers. Such applicator is fitted with thermostatically controlled heating elements and the operation of the applicator is controlled by linkages from the machine. A further form of applicator head is shown in Fig. 10 and comprises an electrically heated body 102 having a well 103 therein and in which rotates an adhesive applying roller 104. The latter is diven by a sprocket 107, the drive to which is prevented until the adhesive is at its working temperature by thermostatic means. Supply of adhesive to the well 103 is from a delivery tube connected to port 110 and via valve 109 in the form of a tubular element 113 controlled by arm 115, the element 113 having a slit therein adapted, upon rotation, to open communications with well 103. A scraper blade (not shown) secured to body 102 is arranged to determine the thickness of the adhesive layer carried by the roller and overflow or other means are provided to control the level of adhesive in well 103. In another embodiment the adhesive applying opening is normally closed by a spring loaded plunger which can be moved against the spring action to permit adhesive to flow through the opening, in timed sequence with the motion of the machine. The apparatus may be connected in a closed circulatory system such that any excess adhesive in the applicator head can be returned to the pre-melt unit by gravity or pump means. For application of adhesive to a waxed surface a heated de-waxing roller may be fitted in front of the adhesive applying head.