IE41548B1 - Improvements in or relating to the manufacture of balls - Google Patents

Abstract

1517502 Applying covers to ball cores DUNLOP Ltd 10 June 1975 [13 June 1974] 26341/74 Heading A6D A ball core 100 may be covered using the apparatus shown in Figures 1, 2 and 8 (and Fig. 3 to 7, 9 and 10 not shown) in which the core is placed in the throughway 76 of a loading plate 8 to locate against a ledge 94. A felt covering piece 101 having one side coated with an adhesive is then positioned in a slot 81 above the throughway 76 (Fig. 8) in the top surface of the loading plate 8 with the adhesive coated side facing the base of the apparatus. A second felt piece 102 also having one side coated with an adhesive is then located in a further slot 82 above a throughway 15, with the adhesive coated side facing towards the top of the apparatus. The loading plate 8 is rotated by means of a handle 93 until the throughway 76 lies between enclosure members 1 and 2 (Figs. 2 and 9). The space defined by the enclosure members 1 and 2 and the throughway 76 is then partially evacuated (to 24 inches of mercury) causing the core to expand. A piston 40b is moved upwards (Fig. 3) to push the core 100 from the throughway 76 against the adhesive coated surface of the felt cover piece 101 and into a locating member 9 in the upper enclosure member 1 causing the cover piece 101 to be wrapped around the core and an upper plunger means 10 to be displaced. Displacement of plunger means 10 causes consolidating members 52 and 53 of a gripping means to engage the ball core to grip it and to assist in wrapping the cover piece 101 around the core. The piston 40b is then withdrawn (Fig. 4) into the lower enclosure member 2. The loading plate 8 is then rotated through 120‹ (Fig. 10) so that throughway 15 lies between the enclosure members 1 and 2 (Fig. 5). The plunger means 10 is then moved down (Fig. 6) causing the consolidating members 52, 53 to release their grip on the ball core which is displaced to contact the adhesive coated surface of the second covering piece 102 and pass into the locating member 12 of enclosure member 2 where the second covering piece is wrapped around the ball core in a manner similar to that described above. The covering pieces are of such a size and shape that a gap exists between their edges when they are located on the expanded core. Upon releasing the partial vacuum from enclosure members 1 and 2, the ball core contracts and the edges of the covering pieces, which have been previously coated with adhesive abut and adhere to each other. The covered ball core is displayed by piston 40b into throughway 15 and is subsequently removed from the apparatus by rotating the loading plate to a position where the throughway 15 is accessible. A further example of ball covering apparatus (Fig. 11, not shown) utilising a rotatable loading plate (150) with throughways and enclosure members (153) and (154) for forming a vacuum chamber is described and functions in a similar manner to the apparatus shown in Figure 1. It may be utilised in a machine (Fig. 22 not shown) for automatically applying felt covering to tennis balls in which ball cores are fed from a hopper (223) and felts are fed from magazines (220) and (221) to a plurality of ball covering apparatuses (201) to (209). Means may be provided to sense the size and shape of the ball core as it is subjected to the partial vacuum and to control the vacuum and the forces exerted by the plunger piston arrangements to limit the deformation of the ball core.

Description

The present invention relates to an improved method and apparatus for the manufacture of balls, such as tennis balls, consisting of cover pieces e.g. of felt wrapped around and adhered to a resilient core.

In accordance with one aspect of the invention there is provided a method of applying two cover pieces at right angles to one another around the surface of a resilient ball core, the method comprising placing two similar dumbbell shaped, cover pieces flat in respective slots therefor in a planar loading plate, the slots having rounded end portions which are generally of the shape of the ends of the cover pieces, moving the loading plate to a position such that a first of said slots lies between enclosures on opposite sides of the loading plate, displacing said core through said first slot into a first of said enclosures so that the cover piece in said first slot is carried with the core into said first enclosure and wrapped around the core, moving the loading plate to a position such that the second of said slots lies between the enclosures and displacing the core from the first into the second of said enclosures through the second slot such that the cover piece in said second slot is wrapped around the core in perpendicular relation to the cover piece already wrapped thereon. 41545 In accordance with another aspect of the invention there is provided apparatus for carrying out the method of the immediately preceding paragraph, the apparatus comprising a planar loading plate movable in its own plane relative to coaxial enclosures on opposite sides of the loading plate to bring in sequence into alignment between said enclosures two elongated slots so position ed in the loading plate that when between the enclosures the slots are in mutually perpendicular orientations, the slots having rounded end portions and each being shaped for the reception flat therein of a similar dumbbel1-shaped piece, each slot communicating centrally with a throughway penetrating the loading plate, there being associated with each enclosure means for displacing a resilient ball core in a throughway in alignment between the enclosures into the other enclosure and consolidating means movable inwardly of the enclosure to wrap around a core in the enclosure the ends of a cover piece displaced with the core into the enclosure.

The invention will now be described by way of example only with reference to the accompanying drawings in which:20 Figure 1 is a cross-sectional view of one example of an apparatus for applying adhesive covers to a ball core; Figures 2 to 7 are schematic cross-sectional views showing the apparatus of Figure 1 in various stages of operation; Figures 8 to 10 are plan views of one component of the apparatus shown in Figure 1; Figure 11 is a part-sectional perspective view of a further example of an apparatus for applying adhesive covers to a ball core; Figures 12 to 14 are part-sectional perspective views of parts of the apparatus shown in Figure 11; Figures 15 to 20 are exploded views of part of the apparatus of Figure 11 shown in various stages of operation; Figure 21 is a schematic view of part of a still further example of an apparatus for applying adhesive covers to a ball core, and Figure 22 is a perspective view of the apparatus, part of which is shown in Figure 21.

In a first example, a test rig illustrating the principles of a machine for applying outer felt covering pieces to a hollow vulcanised rubber centre or core of a tennis ball comprises as shown in Figure 1 two vertically disposed enclosure members 1 and 2, the enclosure member being positioned above and below a horizontal supporting table 3 respectively. The supporting table is supported by three legs, two of which 4 and 6 are shown on Figure 1.

The supporting table 3 is provided with a circular recess into which a planar circular loading plate 8 is located to be rotatable relative to the supporting table 3. The top enclosure member 1 incorporates a locating member 9 which is arranged to support a ball during various stages of the operation, a plunger means 10 for use in releasing the ball from the locating member 9, and a mechanical gripping means 11 utilised to assist in applying the felt covering pieces to the ball core.

The bottom enclosure member 2 is similarly provided with a locating member 12, plunger means 13 and mechanical gripping means 16.

The enclosure members 1 and 2 are arranged to be secured to the table 3 such that the locating members 11 and 12 can be positioned eo-axially with the supporting table and loading plate positioned therebetween. Circular throughways 14 and 15 are provided to extend through the cross-section of the base of the table and loading plate as shown in Figure 1 such that a ball may be displaced from the top enclosure member 1 through said apertures 14 and 15 to the bottom enclosure member 2.

The enclosure members 1 and 2 are connected to a vacuum pump (not shown) so that the air within the enclosure members may be evacuated to provide a vacuum within said members .

The construction of both enclosure members 1 and 2 is substantially the same, and therefore only the top enclosure member 1 will be described in detail. The top enclosure member 1 comprises a cylindrical glass wall portion 20 having circular flange members 21 and 22 positioned at each end thereof. The flange member 21 is of similar diameter to the interior diameter of the cylindrical wall portion 20 and is arranged to rest on a plate 23 which constitutes a top plate secured to the top of the table 3.

An 0-ring seal 24 is positioned between the end of the wall portion 20 and the plate 23 to ensure an airtight seal between the Chamber enclosed by the enclosure member 1 and the surroundings. The flange member 22 is arranged to rest on the opposite end of the wall portion 20 about an annular shoulder portion furnished on the flange 22. An 0-ring 25 is positioned between the end of the wall portion 20 and the annular shoulder to seal the chamber defined within the enclosure member 1 from the surroundings.

A circular recessed portion 27 is provided in the outer face of the flange 22 and is arranged to accommodate a similarly shaped flange 28 provided at one end of the frusto-conical boss 29. The boss 29 is secured to the flange 22 and is provided with an axially extending throughway 30 which accommodates a piston rod 31 comprising part of the plunger means 10. The piston rod 31 is also arranged to extend through an aperture 32 provided within the centre of the enclosure member flange 22. The end of the throughway 30 adjacent the flange 28 of the boss 29 is arranged to be of larger diameter than the rest of the throughway in order to accommodate a cylindrical thrust bush 33 which fits co-axially around the piston rod 31 and also co-axially supports a compression spring 34 the ends of which engage a shoulder 35 furnished within the throughway 30 and a shoulder 36 provided at one end of the bush 33 respectively. Two axially spaced lip seals 37 a'pB are located within the throughway 30 to abut the piston rod to prevent leakage of air into the chamber defined by the enclosure member 1. · The ends of the piston rod 31 which extends into the chamber defined by the enclosure member 1 is connected to a piston 40 which is arranged to extend through an aperture 41 provided in one end of the locating member 9. The outer surface of the locating member 9 is of circular cross-section having a diameter substantially the same as the diameter of a centrally positioned aperture 17 provided in the end flange 21 of the enclosure member 1, such that the locating member 9 is a close fit within said aperture. The inner surface of the locating member is hemi-spherically formed with the end providing the aperture 41 being at the closed end of the half-sphere. The surface of the piston 40 which extends within the aperture 41 is ehaped to complete the spherical profile of the inner surface of the locating member.

The mechanical gripping means 11 comprises two bell cranks 50 and 51 positioned one on each side of the locating member 9, one end of each bell crank is connected to a consolidating member 52 or 53 respectively, the consolidating members being arranged to extend respectively through slots 54 and 55 provided one in each side of the locating member 9. Each bell crank 50 or 51 is pivotally supported about a hinge pin 56,56a and bush 57, 57a. The opposite ends 58 and 59 of the consolidating members 52 and 53 attached to the bell cranks 50 and 51 are arranged to locate within a recess 60 formed by the inwardly facing surface of the thrust bush 33 and the outwardly facing surface 61 of the piston 40. (Inwardly and outwardly as used in this context are used in respect of the mid-plane of the apparatus, i.e. of the supporting table 3) . The end faces of the members 52 and 53 which extend within the locating member 9 continue the curvature of the part-spherical inner surface of the locating member.

The operation of the gripping means 11 is such that when the piston 40 and piston rod 31 are displaced vertically downwards from the position as shown in Figure 1 (i.e. towards the supporting table 3), the ends 58 and 59 of the bell cranks 50 and 51 are held within the recess 60 defined between the; piston 40 and the thrust bush 33 and are displaced with Lhfe piston and piston rod by the bush 33 as the spring means expands from the position as shown in Figure 1. The displacement of the ends 58 and 59 of the bell cranks 50 and 51 causes the bell cranks to pivot about their respective hinges 56,56a. thereby causing the consolidating members 52 and 53 to be displaced away from the locating member 9 via the slots 54 and 55.

The bottom enclosure member 2 is substantially the same as the top enclosure member 1 described above, except that the gripping means 16 of the enclosure member 2 is disposed at 90° to the gripping means 11 of the enclosure member 1. The. disposition of the gripping means of the two enclosure members ensures that when the ball core is passed from one enclosure member to the other the gripping means will alternately engage the diametrically opposed halves of the ball.

As previously described the supporting table 3 comprises a circular body portion furnished with a centr illy positioned circular recess 7 into which is located the 418 4 8 circular loading plate ll. The circular loading plate is pivotally mounted about its centre about an axially extending shaft 5 which is arranged to extend through the loading plate 8 and to be rotatably located within bosses 73 and 74 positioned one on the top plate 23, and the other on the base of the supporting table 3 (shown in Figures 2 to 7). The loading plate 8 is provided with two axially extending throughways 15 and 76 (the throughway 76 is not shown in Figure 1 but is shown in Figures 2 to 4 and 8 to 10).. The two throughways 15 and 76 are off-set from the centre of the loading plate 8 and are positioned on a common pitch circle drawn from the centre of said plate, such that on rotation of the plate 8 the throughways 15 and 76 in turr co--axially pass over the aperture 14 which is provided in the base of the supporting table 3.

The upper surface (as viewed in Figures 8 to 1CJ of the loading plate 8 is provided with two milled slots 81 and 82, each of which is profiled to accommodate a felt covering piece. The centre of each slot is enlarged by a circular aperture which constitutes the throughways 76 or 15- The throughway 15 is arranged to be of greater diameter than the throughway 76 for the purpose which will be later described.

The supporting table 3 and loading plate 8 are covered by the circular top plate 23 having a diameter the same as the diameter of the supporting table and being provided with a circular throughway 90 (Figure 1) which is positioned co-axially over the aperture 14 provided in the base of the support table The throughways 15 and 76 of the loading plate 8 can therefore be brought into coaxial alignment, with the the throughway 90 and aperture 14 as the loading plate rotates.

The top plate 23 is secured to the supporting table 3 by bolts 77 (shown in Figures 2 to 7) which are arranged to screw into threaded apertures 75 provided with table 3, and is held in sealed engagement with the supporting table 3 by means of an annular O-ring 91 which locates within an annular groove 92 provided in the top face of the supporting table 3. The top plate 23 is also provided with a kidney-shaped aperture 120 (shown on Figures 8 to 10). The aperture 120 is· positioned away from the circular aperture 90 (Figure 1) i.e. away from the enclosure members 1 and 2 and is arranged to be covered in a sealed manner by a cover member (not shown). The axially extending mounting shaft 5 is arranged to extend co-axially above and below the table 3 parallel to the axis of the enclosure members 1 and 2. The shaft also co-axially supports a lever 93 (Figure 2) such that on displacement of the lever 93 the plate 8 is axially rotated within the recess 7 relative to the table 3.

As shown in Figure 2 the base of the throughway 76 of the loading plate 8 is provided with an annular ledge 94 which reduces the diameter of the throughway such that a ball core is prevented from passing therethrough but the pistons of the plunger means are not impeded. The ledge 94 is furnished with an upper arcuate surface 95, profiled to support the ball core. The thickness of the loading plate 8 is arranged to be slightly greater than the diameter of the ball core such that a core may be positioned in the throughway 76 to rest on the annular ledge 94 without the bal I protruding vertically above I ln> upper surlnre of the plate 8.

The operation of the apparatus is shown in Figures 2-10 and comprises the following sequence of events.

The cover portion (not shown) is removed from the top plate 23 to expose the kidney-shaped aperture 120 (Figures 8 to 10), a ball core 100 is positioned in the throughway 76 of the loading plate 8 to locate against the ledge 94 as previously described. As shown in Figure 8 a felt covering piece 101 is positioned flat in the Slot 81 provided in the top surface of the loading plate 8 with the adhesively coated side lying facing the base of the apparatus and the felt side facing towards the enclosure means 1.

An additional felt piece 102 is located fTat within the other slot 82 with the adhesively coated side facing upwardly and the felt side facing towards the second enclosure member 2, i.e. upsidedown with respect to the first felt piece 101.

The loading plate 8 is rotated by means of the handle 93 via the axially extending shaft 5 such that the throughway 76 is in the position as shown in Figures 2 and 9, that is with the first felt piece 101 and core ball 100 positioned between the enclosure members 1 and 2.

Because the two enclosure members 1 and 2 as previously described are substantially identical, the components of the enclosure member 2 (bottom enclosure member) will be designated by the same reference numerals as the reference numerals used for the upper enclosure member 1, except that the prefix b will be used for the components of the bottom enclosure member. When the ball core 100 has been positioned between the enclosure members and 2 (Figure 9), the space enclosed within the enclosure members is evacuated by a vacuum pump (not shown) via an outlet port 110 provided in the base of the enclosure member (Figure 2). The enclosure members are evacuated to a vacuum pressure of 24 inches of mercury. Evacuation of the air space surrounding the ball core causes the core to expand for a purpose which is disclosed later in the specification.

The plunger means 13 of the bottom enclosure member 2 is displaced vertically upwards so that the piston 40b firstly abuts the base of the core 100, and secondly on subsequent displacement of the piston rod 31b, the piston 40b pushes the core 100 from the throughway 76 of the loading plate 8 against the adhesively coated surface of the felt cover piece 101 and into the locating member 9 of the upper enclosure member 1. As the core 100 is displaced into the locating member 9 of the enclosure member 1 the plunger means 10 of the upper enclosure member is displaced vertically from the position as shown in Figure 2 until it assumes a position as shown in Figure 3. Displacement of the core 100 also causes the cover piece 101 to be wrapped around the core 100, firstly by the spherical form of the inner surface of the locating member 9 and secondly by the consolidating members 52 and 53 of the mechanical gripping means 11. As the plunger means 10 is displaced vertically the consolidating members 52 and 53 are displaced inwardly of of the locating member via the bell cranks 50 and 51 which pivot about the hinges 56 and 56a,. As the ball core is pushed firmly into the locating member 9 by the piston 40b via the piston rod 31b of the lower enclosure member 2, the cover piece 101 is firmly located against the outer periphery of the core 100 as shown in Figure 3. The plunger means 13 is subsequently withdrawn to assume the position as shown in Figure 4.

The loading plate 8 is rotated through 120° by the lever 93 via the mounting shaft 5 to assume the position as shown in Figures 5 to 7 and 10. With the loading plate 8 in this position relative to the enclosure members 1 and 2, the second cover piece 102 is positioned vertically below the ball core 100 which is gripped by the consolidating members 52 and 53 and is located within the locating member 9 of the enclosure member 1. The longitudinal axis of the second felt piece 102 is arranged to be at 90° to the longitudinal axis of the first felt piece 101 (illustrated in Figures 9 to 11) and is arranged such that when the first felt piece 101 is applied to the ball core 100 as shown in Figure 3, a space 106 defined by one half of the outer surface of the ball core is left uncovered, the other half of the ball core being covered by the first felt member 101. The plunger means 10 of the upper enclosure member 1 is displaced vertically downwards thereby forcing the consolidating members 52 and 53 to be pivoted via the hinges 56 and 56a outwardly of the locating member 9 and allowing the ball core 100 to be displaced vertically down from the locating member 9 onto the adhesive coated surface of the second covering piece 102, through the second throughway 15 of the loading plate 8 and into the locating member 12 of the the bottom enclosure member 2, the piston 40b yielding to permit this and lower the core into the member 12. Because the first covering piece 101 has been already positioned on the ball core 100, the diameter of the ball core plus felt piece 101 is greater than the original diameter of the ball core and therefore the throughway 15 in the loading plate 8 has to be 0 of greater diameter than the throughway 76.

As the ball core 100 is pushed into the locating member 12 of the bottom enclosure member 2, the second covering piece 102 is folded around the uncovered portion 106 of the ball core 100 by the part-sj)herical profile of the 5 inner surface of the locating member 12 and by the action of the consolidating members of the mechanical gripping means 16. The consolidating members are displaced towards the ball core and are arranged to push the edges of the covering piece 102 against the outer surface of the core 3 100 until the ball core assumes the appearance as shown in Figure 6.

To ensure correct positioning of the covering pieces on the ball core it is important that displacement of the plunger means will not cause rotation of the ball core relative to the loading plate. For this purpose each of the piston rods 31 and 31b of the plunger means 10 and 13 is coupled by a forked member (not shown) to the vertically extending mounting shaft 5, so that the piston rods 31 and 31b are displaceable parallel to the shaft 5 but are not rotatable relative to the shaft 5.

As shown in Figure 6 the ball core 100 is located within the locating member 12 of the enclosure means 2 with the pistons 40 and 40b of the enclosure members 1 and 2 respectively abutting opposite sides of the ball, and with the felt covering pieces 101 and 102 covering virtually the whole of the outer periphery of the ball. A gap 107 is provided between the edges of the felt pieces 101 and 102 defining a Cassinian outline. The edges of each of the covering pieces 101 and 102 are previously coated with a contact adhesive and as previously described it is important that when the covering pieces are applied to the ball core the edge of one piece does not abut the adjacent edge of the other cover piece before the covering pieces have been finally positioned on the core 100. By subjecting the enclosure members 1 and 2 to a vacuum the diameter of the ball core is expanded prior to the application of the cover pieces due to the pressure of the air within the hollow ball core being greater than the ambient pressure in the enclosures. The expansion of the ball core means and the cover pieces 101 and 102 do not quite cover the whole outer surface of the ball core and therefore the gap 107 is formed between the edges of the cover pieces.

When the vacuum pressure is released via the port 25 110 provided in the bottom enclosure member 2 as shown in Figure 7, the ball contracts, thereby reducing the gap 107 defined between adjacent edges of the cover pieces so that the adjacent edges of the cover pieces come into abutting contact with each other and are adhesively secured together. The ball with the cover pieces located on its outer surface may be subsequently displaced from the locating member 12 of the bottom enclosure member 2 by the plunger means 13 vertically upwards into the throughway 15 provided within the loading plate 8. On rotation of the plate 8 by the lever 93 the ball may be displaced away from the enclosure members I and 2 to a position vertically below the unloading cover (not shown), the cover may be removed and the covered ball removed from the apparatus.

In a further example of a test rig shown in Figure 11, for applying felt covering pieces to a resilient tennis ball core, a loading plate 150 is positioned within an enclosure 151 between upper and lower plates 152 and 152A to be rotatable therein in the horizontal plane in a manner similar to the previously described construction. Upper and lower enclosure chambers 153 and 154 are positioned coaxially above and below the loading plate 150 and throughways 155 and 156 are provided in the upper and lower plates 152, 152A respectively to interconnect the upper and lower chambers. The enclosure chambers are arranged to be subjected to vacuum in the same manner as previously described· A loading/unloading station is provided on a common pitch circle with the chambers and this station includes a circular aperture 157 provided in the top plate 151 covered by a swivelling sealed cover member 158. An aperture 159 is provided in the lower plate 152 A through which a plunger means 160 is arranged to be displaced vertically to engage 41648 a finished ball to eject the ball from the loading plate 150 through the aperture 157 in the top plate. The ejection plunger 160 is similar to the plungers previously described except that there is no means to engage the sides of the ball.

The loading plate 150, instead of having two apertures and 76 as shown in Figures 8 to 10, is provided with three apertures 161, 162, 163 equally spaced at 120° from each other on a common pitch circle; two of the apertures 161, 162 are provided with recesses (slots) 164, 165 similar to the slots 80 and 82 shown in Figures 8 to 10, and the third aperture 163 iS Of circular cross-section and has no slot. Each aperture is arranged to serve as an entry into one of three cavities 166, 167, 168 provided within the body of the loading plate 150 and shown in Figures 12, 13 and 14.

The cavities are arranged to be of sufficient depth to hold a tennis ball so that the ball does not protrude above the upper and lower surface of the loading plate. The first cavity 166 (Figure 12) is provided with a hemispherical bottom portion 170 with a hole 171 in the base of said portion to allow the passage of a push rod. The hemispherical bottom portion 170 prevents the ball from being displaced through the cavity 166. The second cavity 167 (Figure 13) is of a circular cross-section slightly larger in diameter than a finished tennis ball and is provided with a large aperture 173 within its base which allows the ball to pass through the cavity. The third cavity 168 (Figure 14) is provided with a hemispherical bottom portion 174 and a small aperture 175 substantially similar to the first cavity. The diameter of the entry aperture 161 of the first cavity 166 is arranged to be the same as the diameter of the ball core when expanded, whilst the diameter of the entry aperture 162 of the second and third cavities 167, 168 are arranged to be of the diameter of the expanded core plus the thickness of two felt covering piece·.

The enclosure chambers 153 and 154 are substantially the same as the chambers described in the previous example and will not be described in detail.

The sequence of operation using this modified rig LO is slightly different to the previously described operation and is illustrated with reference to Figures 15 to 20 which are schematic views of the upper and lower plates 152, 152A and loading plate 150 in various positions relative to the enclosure members. The views are shown in exploded form to highlight the detail of the operation.

Figure 15 shows the assembly at the start of the cycle with a completed tennis ball 184 in the upper enclosure member 153 and the first cavity 166 positioned directly underneath the aperture 157 in the upper plate 152 with the sealed cover 158 displaced away from the aperture 157. A ball core 180 is positioned within the cavity 166 in the loading plate 150 and a first felt 181 covering piece is positioned within the associated slot 1 64 with the adhesive face facing towards the ball core. whilst the core and fi :st felt covering piece are being loaded at the loading station the plunger on the upper enclosure chamber 153 is actuated to push the completed ball 184 from the upper chamber into the third cavity 168 in the loading plate 150. The plate is subsequently rotated through 120° to bring the first cavity 166 directly underneath the enclosure chambers as shown in Figure 16, The second cavity 167 is then positioned at the loading stage. The push rod associated with the upper enclosure member 153 is then displaced downwardly until its piston engages the core located in the first cavity 166 in the loading plate 150.

As shown in Figure 17 a second felt 182 is then positioned within the slot 165 associated with the second cavity 167 with the adhesive face of the felt facing upwardly towards the upper plate 151. The sealed cover 158 is. then positioned over the aperture 157 in the top plate to seal the assembly. The vacuum is then applied to expand the core.

The push rod associated with the lower enclosure chamber 154 is then displaced upwardly until its piston engages the lower face of the ball core 180; both push rods are then displaced upwardly forcing the ball and first felt cover piece into the upper enclosure member 153 and into engagement with consolidating members of the gripping means and thereby forming the felt cover Diece round one half of the periphery of the ball as described previously. The lower push rod is then fully retracted until it is within the lower enclosure chamber 154.

The loading plate 150 is subsequently indexed through a further 120° so that the second cavity 167 and the second felt covering piece 182 is positioned in alignment with the enclosure members (Figure 18). The third cavity 168 containing the completed ball 184 is positioned underneath the loading '-station. The lower push rod is displaced upwardly t.o cause its piston to engage the nonadhesively coated face of the'second felt cover oiece 182 and to transfer the second felt cover piece to the adjacent face of the ball core'180 which is located in the upper enclosure member 153. When the piston of the lower push rod engages the cover piece on the ball core both push rods then descend with the core plus the two felts 181 and 182 (the first felt having already been formed on the ball), transferring the ball and felts through the loading plate 150 and second cavity 167 to the bottom enclosure chamber 154 where the second felt cover piece 182 is formed round the ball and the ball is held by the lower gripping members.

The felt cover piece is applied to the ball substantially as described earlier in the specification. The ball is now located in the lower enclosure member 154 with both felt cover pieces applied to it. It is then transferred through the loading plate 150 and back to the top enclosure chamber 153 where it is gripped by the consolidating members of the upper gripping means es shown in Figure 19. The lower pbsh rod is subsequently fully retracted back to the lower enclosure chamber 154.

The vacuum is then released and the sealing cover 158 removed from the aperture 157 in the upper plate (Figure ). It will be noticed that the completed ball 184 that was originally in the upper enclosure member 153 at the start of the cycle (Figure 1) is now in the third cavity 168 and the push rod associated with the lower plate directly under25 neath the cavity 168 may be activated to push the ball clear of the loading plate 150 and eject the ball through the aperture 157 in the upper plate. The loading plate 150 i·. then indexed through a further 120° to bring the first ca-’ity 41848 166 directly underneath the loading station as shown in Figure 15.

It will be noticed that after one revolution a completed ball is located in the upper enclosure member (Figure 19) and that the assembly has completed one full cycle. In other words, from the stage when a core is positioned in the loading plate to the stage where the completed ball is ejected from the loading plate, the loading plate goes through one and two thirds revolutions, the ball is formed after two thirds of a revolution but is located in the top chamber and then after the next 1/3 revolution when another ball is being loaded, the completed ball is transferred from the upper enclosure member to the third cavity and eventually to the loading station where it is ejected.

A rig of the kind described above is ideally suited for implementation into a machine for automatically applying felt covering pieces to tennis ball cores and the basis of one such machine is shown in Figure 22 with the details of operation illustrated in Figure 21.

In essence, the machine comprises a rotatable head 200 which contains nine ball covering assemblies 201-209 of the kind illustrated in Figures 11 to 20, equally spaced around a common circle about the rotational axis of the head assembly 200. Each of the ball covering assemblies is arranged to have a loading plate 150 of the kind described above which is axially rotatable within a respective cell in the head 200 and is provided with an upper 153 and lower 154 enclosure member shown in Figure 22, The head assembly 200 is also rotatable about a vertical axis and is arranged to index through intervals of 40° in an anticlockwise direction as viewed in Figure 21 to define nine stations numbers A to J. The loading plate 150 of each cell is arranges to be indexed at intervals Of 120° as previously described.

The sequence of operation is as follows. A ball covering assembly positioned at station A is loaded into cavity 1 (see Figure 11) of the loading plate and the head 200 is indexed through 40° to bring the ball covering assembly to station B where the first felt cover piece is laid flat in cavity 1. As the head assembly is indexed to move the ball covering assembly between stations B and C the loading plate is rotated through 120°, and at C a second felt cover piece is laid flat in cavity 2. At station D, the sealed cover member 158 is positioned over the loading plate and the vacuum is applied causing the ball core to expand. At station E the first felt cover piece is applied to the ball core in cavity 1 and the ball core is retained in the upper enclosure chamber. Between stations E and F the loading plate rotates through 120° so that the second felt cover piece can be presented to the ball core which is held in the upper enclosure chamb;r.

At station F the second felt cover piece is applied to the core as previously described and the ball is transferred back to the upper chamber. At station G the vacuum is released and the sealed cover removed. At station H the ball which has been covered in the previous cycle and held in cavity 3 throughout the previous seven stations is ejected from cavity 3 Whilst the head rotates between station H and station J the loading plate rotates a further 120° to bring the cavity 1 back to the loading position. The ball that has just been covered is then transferred from the upper enclosure member to cavity 3 and will be carried round the whole cycle until it reaches station H and will then be ejected. The head then indexes through a further 40° to complete 360° rotation to bring the cavity 1 back to stage A where a further core is positioned in cavity 1, thereby completing the cycle.

It will be seen that the loading of the core and felt cover pieces takes place at stations A, B and C and that the vacuum is applied between stations D and G and that ejection of the completed ball takes place at station H on the second ci rcui t.

As shown in Figure 22 two magazines 220 and 221 of felt cover pieces stacked in a vertical pile may be positioned over station B and station C respectively and may be arranged to apply a felt to the loading plate when required. A ball core hopper 223 may be positioned over station A and may be arranged to present a core to the respective cavity in the load ing plate when required. An automatic ejection system (not shown) may also be provided at station H so that once the machine has been loaded with cores and felt cover pieces it can be switched on and will automatically cover the ball cores and eject them thereby totally removing labour dependence from the covering operation.

Alternatively an operator may be positioned to load the ball cores and check that the felt cover pieces are being correctly applied to the loading plates.

In order to obtain uniformity in finished ball sizes, it is important that the ball core, when subject to vacuum is expanded to a uniform diameter and that the core or core plus felt cover pieces is not deformed when engaged by the oistons of the push rods.

Because of the variations in wall thickness of ball cores and the differing pressure therein, there is a danger that when a predetermined vacuum is applied to the core the balls will expand to different diameters thereby causing misfitting of the felt cover pieces. In order to overcome this problem it is proposed to provide four sensors (not shown) in the cavity in which the ball core is located, and spaced equally around the circumference of the ball so that when the vacuum is applied and the ball expands, the outer surface of the ball will engage the sensors and a signal will be passed from tho sensors to the vacuum pump or a bleed valve to ensure that the level of vacuum is adjusted so that the ball expands to a predetermined diameter. The provision of these sensors allows for any variations in wall thickness and differences of internal pressure of the ball cores.

There is also a danger that when the upper and lower pistons engage the surface of the ball that they will deform the ball, again causing misfitting of the felt cover pieces. To overcome this problem it is proposed to provide overload sensors (not shown) at diametrically opposed positions relative to the ball core so that when the pistons of the push rods engage the ball core the degree of ball deformation is limited by the sensors passing a signal back to push rod actuators to limit the load applied to the ball.

With the above two sensing devices it is hoped that the felt cover pieces may be applied to ball cores to produce a finished ball which possesses the required quality control standard thereby reducing the number of reject balls.

As previously described, in order to cover the ball cores, each core is previously coated with an adjesive , and is then expanded. The felts, coated With adhesive on one side, are subsequently applied to the expanded ball core to leave an oversize gap between the felt cover pieces. Each felt cover piece has its periphery thickly coated with an adhesive so that when the vacuum is released, the gap between the pieces is diminished so that the adhesively coated edges of the cover pieces come into abutting contact with each other and are adhesively secured together.

It has been found that when the felt cover pieces are stacked in a machine of the kind shown in Figure 22 because of the thick coating of 2o adhesive on the sides of each felt cover piece, it is difficult to separate a felt cover piece from the stack. It has been proposed therefore that the ball core should be coated with a thick layer of adhesive and the amount of adhesive on the edge of the felt cover pieces should be reduced so that after the felt cover pieces have been applied to the expanded core and the vacuum is reduced and the balls passed to a curing chamber, curing of the ball core causes the adhesive between the felt cover pieces and the core to flow into the groove defined between the felt cover pieces, and as this groove is reduced the edges come into abutting contact with the adhesive therebetween. It is hoped that by reducing the amount of adhesive on the edges of the felt cover pieces that they can be easily stacked in a machine of the kind shown in Figure 22 and that problems of separating a single felt from the stack can be overcome.

Claims (8)

1. A method of applying two cover pieces at right-angles to one another around the surface of a resilient ball core, the method comprising placing two similar, dumbbell-shaped cover pieces flat in respective slots therefore in a planar loading plate, the slots having rounded end portions which are generally of the shape of the ends of the cover pieces, moving the loading < plate to a position such that a first of said slots lies between enclosures on opposite sides of the loading plate, displacing said core through said first slot into a first of said enclosures so that the cover piece in said first slot is carried with the core into said first enclosure and wrapped around the core, moving the loading plate to a position such that the second of said slots lies between the enclosures and displacing the core from the first into the second of said enclosures through the second slot such that the cover piece in said second slot is wrapped around the core in perpendicular relation to the cover piece already wrapped thereon.

2. A method as claimed in claim 1, wherein a hollow core is used and wherein the core is subjected exteriorily to a partial vacuum during its displacement between the enclosures so that the core is in an expanded condition when the cover pieces are applied to it, so that there is a gap between the applied cover pieces, and wherein the resumption by the core of its former diameter when the finished ball is relieved of partial vacuum brings the cover pieces together to reduce the gap.

3. Apparatus for carrying out the method claimed in claim 1, comprising a planar loading plate movable in its own plane relative to coaxial enclosures on opposite sides of the loading plate to bring in sequence into alignment between said enclosures two elongated slots so positioned in the loading plate that when between the enclosures the slots are in mutually perpendicular orientations, the slots having rounded end portions and each being shaped for the reception flat therein of a similar dumbbell-shaped cover piece, each slot communicating centrally with a throughway penetrating the loading plate, there being associated with each enclosure means for displacing a resilient ball core in a throughway in alignment between the enclosures into the other enclosure and consolidating means movable inwardly of the enclosure to wrap around a core in the enclosure the ends of a cover piece displaced with the core into the enclosure.

4. Apparatus as claimed in claim 3 for carrying out the method of claim 2, wherein means is provided for maintaining the core under an exteriorily applied partial vacuum throughout the operations of exchanging it between the enclosures so that a hollow core is in an expanded condition when each cover piece is applied to and wrapped around the core.

5. Apparatus as claimed in claim 3 or claim 4 wherein each enclosure comprises a locating member having a part-spherical inner surface open to the loading plate and wherein the consolidating means associated with each enclosure comprises a pair of consolidating members having end portions movable inwardly from opposite sides of the enclosure, which end portions are shaped to continue the part-spherical configuration of the interior of the enclosure when moved inwardly thereof.

6. A method of applying two cover pieces ar right-angles to one another around the surface of a resilient ball core substantially and as snown in the accompanying drawings as herein described.

7. Apparatus for carrying out the method claimed in 5 any of claims 1 - 6 constructed and arranged to operate substantially as herein described and as shown in the accompanying drawings.

8. A ball made by the method claimed in any of claims 1 - 6 or by means of the apparatus claimed in any of claims 3-5 and io 7.