Technical Field

The present invention relates to an apparatus and method for applying seam sealing tape to an item of footwear mounted on a last. It is particularly, though not exclusively concerned with the production of waterproof breathable footwear where seams are sealed in order to ensure water tightness.

Background

Waterproof breathable (i.e. water-vapour-permeable) materials are available from W.L. Gore & Associates under the trademark Gore-Tex. These comprise a thin membrane of porous polytetrafluoroethylene (PTFE) which may be produced in the manner described in US patent 3,953,566. Usually, the porous expanded PTFE membrane is coated with an oleophobic coating, as disclosed in US patent 4,194,041, in order to prevent the membrane from being wetted-out by fats or oils from the wearer's body. However, other waterproof breathable membranes (such as polyurethanes) are available on the market and the invention is applicable to these also.

In order that the shoe should be fully watertight, it has been conventional practice to initially produce a bootee of a relatively soft waterproof breathable material around which the shoe is constructed. The bootee includes

SUBSTITUTESHEET

an opening for the foot and is usually formed from two side portions and a sole portion. The joins are generally butt-edged, secured with zig-zag stitching and the seams are sealed. The bootee can then be pre-tested for leaks before being put into the final shoe. Typically, the bootee is formed of a conformable four layer laminate comprising from the outside inwards; a layer of nylon knit, a membrane with oleophobic coating, a foam layer and an inner fabric lining to go adjacent the foot.

However, the flexible nature of the bootee can cause difficulty in subsequently aligning the bootee on a last in order to allow the upper and outer sole to be attached.

Our co-pending patent application GB9203714.2 discloses an alternative method of forming the footwear, which involves the step of lasting an upper portion around the periphery of a midsole and sealing the overlapping lasting margin with seam sealing tape. This ensures the water-tightness of the seam.

The technique of seam sealing is a known technique which is currently used for sealing the seams of waterproof garments and bootees used for waterproof footwear. In this technique, a tape of width typically l-2cm is adhered over the seam using a hot melt adhesive under pressure from a pressure roller. In the case of PTFE type materials, special adhesives which adhere to the PTFE membrane are required and a suitable pressure must be employed to force the adhesive into the structure of the

PTFE membrane. In order to achieve a satisfactory result, careful control of the conditions under which the tape is applied is required.

Hitherto, seam sealing tape has been applied to conformable items such as bootees or garments. It has not generally been practical to apply seam sealing tape satisfactorily to non-conformable items such as lasted footwear. For this reason, in the case of footwear produced according to GB9203714.2, this requires that the part assembled shoe must be removed from the last on which it is being assembled before the seam sealing operation can be carried out. The last must then be re-inserted after seam sealing to allow completion of the shoe assembly process. This is expensive in time and effort and adds to the cost of footwear produced in this way.

It is an object of the present invention to mitigate these problems by providing an apparatus which can carry out seam sealing operations on footwear which is mounted on a last.

Summary of the Invention

The present invention provides an apparatus for applying seam sealing tape to an item of footwear mounted on a last, which comprises; a moveable table means for supporting the footwear mounted on the last, comprising mounting means for mounting the last on the table means;

the table means being mounted in the apparatus such as to allow movement in a longitudinal direction and movement in a transverse direction thereto; tape applicator means comprising pressure means (e.g. a roller means) for applying seam sealing tape onto the lasted footwear, means enabling movement in an upward direction to follow variations in the contour of the lasted footwear, and pressure control means to maintain a pre-determined (usually constant) pressure on the pressure means during application of the seam sealing tape.

The invention also relates to a corresponding method. Generally, the last is mounted to the moveable table means by means of a pin which fits into an ankle portion of the last and is secured to the table means. If desired, the pin may be mounted on a pivot to enable pivotting of the last around an axis extending in a longitudinal direction. In order to clamp the last securely in position during the seam sealing operation, the clamping means may include a cup to support the toe portion of the last and the footwear; and clamping means to secure the periphery of the last and footwear.

The moveable table means preferably comprises a first table moveable along a track in a longitudinal direction, and is usually provided with appropriate drive means. A second table moveable in a transverse direction may be mounted on the first table, so as to move transversely

along a track provided on the first table. The transverse movement of the second table may be achieved manually so as to follow the seam which is being sealed. However, in a preferred embodiment this is automated by providing a template which carries the outline of the seam, and which is tracked by an arm mounted on the second table, so that the transverse movement is effected to automatically track the template.

Generally, two outlines are provided, each for one side of the footwear. In this way, one side of the peripheral seam is taped first using the first template. The last is then moved transversely so that the other side of the seam is under the tape applicator means, and the other side of the seam is taped.

If necessary, the movable table means or the tape applicator means may be rotated around an upright axis in order to facilitate taping of the toe and heel portions. Rotation may be manual or achieved automatically by providing a suitable guide.

The tape applicator means comprising pressure means (e.g. a roller) , means for enabling movement thereof in an upward direction (relative to said longitudinal and transverse directions) , and pressure control means may be of conventional construction known in the art. This allows the applicator means to follow upward variations in the contour of the footwear; for example, where a flat midsole of a shoe adopts a curved orientation.

In this way, seam sealing tape may be applied to a peripheral lasting seam in a manual, semi-automatic or fully automatic manner, whilst the shoe or other item of footwear is still in place on the last. Following seam sealing, assembly of the shoe may be completed, for example by the application of an upper and an outer sole.

Detailed Description of Preferred Embodiments

Embodiments of the invention will now be described by way of example only with reference to the drawings wherein;

Figure 1 is a partially cut away view of a partially assembled shoe mounted on a last and having a peripheral lasting seam;

Figure 2 is a schematic elevation of a seam sealing apparatus according to the present invention;

Figure 3 is a schematic partial plan view of the table and template;

Figure 4 is a side elevation of the apparatus;

Figure 5 is a plan view of part of the table assembly;

Figure 6 is an elevational view; and

Figure 7 shows a mechanism for rotating the table.

Figure 1 shows an inner lining of a shoe comprising a lining upper portion 4 sealed to a midsole 12 by means of adhesive and seam sealing tape 24. The midsole is attached by tacks 14 to the underside of last 50. The holes left by the tacks are ultimately sealed with patches

28.

The lining upper portion and the midsole are each formed of a laminate comprising a lining material and a midsole board respectively, each being laminated to a layer of water-impermeable, water-vapour-permeable expanded porous PTFE carrying an oleophobic coating and having on an outer surface thereof a knitted open nylon fabric (material available from W.L. Gore & Associates (UK) Ltd. under the trademark Top-Dry) . The laminate is arranged so that the porous expanded PTFE layer and nylon fabric are outermost.

Firstly, the upper portion 4 of the inner lining is produced from panels of the leather laminate by seaming the panels together (for example, heel, vamp and tongue panels, or other construction known in the art) to construct a part-bag shape, stitching the panels together with a lock stitch, and sealing the seams. The midsole laminate 12 is then attached by tacks 14 to the underside of a last. Using conventional techniques, the upper lining portion 4 is lasted over the last so as to adopt its shape and a lower marginal portion 16 thereof is left protruding beyond the underside of the last. An adhesive layer is applied around the periphery of the midsole and the marginal portion 16 of the lining upper portion 4 is folded around the underside of the mid-sole periphery and adhered thereto. This results in puckers 22 which may be removed, or alternatively avoided by sculloping the

marginal portion 16.

The peripheral seam 26 which is formed needs to be sealed with seam sealing tape 24 as will be described hereafter in order to waterproof the seam.

Figures 2 and 3 are schematic drawings illustrating the principles of the present invention.

Figure 2 shows a seam sealing apparatus having a frame 30 and base plate 32. A vertically moveable tape applicator assembly 34 is attached to the end of the arm of the frame and includes a pressure roller 36. If required, the tape applicator assembly may swivel about its vertical axis particularly for applying tape to the toe and heel areas of the seam.

A moveable table comprises a first table 40 moveable in a longitudinal direction on bearings 41 and a second table 42 mounted on top of the first table and moveable transversely relative thereto on bearings 43. Attached to one side of the upper table 42 is a feeler arm 44 which traces an outline 46 (corresponding to one side of the seam to be sealed) on the edge of a template 48 mounted on the base plate.

Last 50 is mounted on the second table via a swivel pin 52 allowing swivelling around a longitudinal axis. A clamp (not shown) is provided for clamping the shoe in position.

Figures 4 to 6 are respective side elevations, plan views and front elevations of a practical seam sealing

apparatus .

The first table 40 is mounted on a pair of ball races 41 which run within a channel 60 on base 32. The table is longitudinally moveable by means of a belt 62 attached to each end of the table, and which passes around a pair of pulleys 64 and 66, round a further pair of pulleys 70, 71 and round a pneumatic drive mechanism and clutch 68. Operation of the drive 68 moves the belt 62 and drives the table 40 in a longitudinal direction.

The second table 42 is transversely moveable on a pair of ball races 43 guided along rails 72 mounted on the first table.

A cranked arm 80 (analogous to feeler arm 44 in Figure 2) is pivotally attached at 82 to a bracket 84 mounted on the first table. The arm 80 (shown in folded position) is to trace along outline 46 and thereby transversely guide the last along the chosen seam sealing path. A lever 86 is pivotally attached at 87 to one end of the cranked arm 80 and at the other end is pivotally attached at 88 to the second table 42 so as to control transverse movement of the second table 42 relative to the first table 40.

The toe portion of the last 50 is supported in a cup 90 also mounted on the second table 42. The peripheral edges of the last are engaged by a pair of clamping arms 92, 94 pivotally attached at 93, 95 to the second table. A pneumatic drive/clutch assembly 96 operates to move the

clamping arms into and out of engagement with the periphery of the last. A similar assembly (not shown) operates to swivel the last about an axis of swivel pin 52 such that the roller 36 is able to adopt one of the two positions shown in dotted lines, i.e. to track along both sides of the peripheral seam 24.

The tape applicator assembly comprises a pressure roller 36 mounted on arm 34. Conventional pneumatic pressure control means (not shown) are employed to exert a constant pressure on the pressure roller irrespective of the vertical position of the tape applicator assembly. This allows seam sealing tape to be applied onto a midsole which is not flat, but has a contour which is curved in an upward direction. The seam sealing tape has a coating of hot melt adhesive on one side and this is melted prior to application to the seam by means of hot air directed through a nozzle assembly 98. Various vertically displaced positions of the tape applicator means are shown in Figure 4.

The apparatus shown in Figures 4 to 6 may be operated as follows. Firstly, the lining upper 4 is lasted around and adhered to the midsole board 12 (tacked to the last 50) such that the lasted margin 16 is adhered to the midsole board leaving a peripheral seam 26 to be taped. The last with attached midsole/lining upper assembly is then fitted onto the seam sealing apparatus by fitting over pin 51. The toe of the last is engaged in cup 90.

Clamping arms 92, 94 are engaged to grip the periphery of the last and hold it in position. The seam sealing apparatus is then operated so as to tape first one side of the seam from heel to toe (or vice versa) and then the other side of the seam from heel to toe (or vice versa) in two separate movements. Seam sealing tape passes under the pressure roller 36 and the hot melt adhesive is melted by means of a jet of hot air from nozzle 98 such as to adhere the tape 24 over the seam 26. The drive means 68 is operated so as to longitudinally move the first table 40 in a heel to toe direction. The feeler 44 tracks (manually or automatically) the outline 46 on~the template 48 and causes transverse movement of the second table 42 relative to the first table 40. In this way, the tape applicator tracks one side of the peripheral seam 26 applying seam sealing tape over the seam. When the tape applicator reaches the toe, the tape is applied around the toe portion by rotating the second table around an upright axis. The tape is then cut and the last is moved over so as to allow taping of the other side of the seam 26 from toe to heel. Alternatively, the seam sealing tape may be applied all round seam 26 in a single movement.

After the seam has been completely taped, the tape is cut and the last with the partly assembled shoe still mounted thereon is removed from the apparatus, ready for assembly of the shoe to be completed elsewhere.

Although as described above, the second (upper) table

42 or the last itself can be rotated manually in order to apply seam sealing tape to the toe and heel regions, this may also be achieved automatically. Figure 7 shows schematically a mechanism for rotating second table 42 relative to first (lower) table 40, around axis 100 in the direction shown by the arrow, which comprises static rotation guide means in the form of a peg 102 mounted on the corner of second table 42 which tracks along a slot 104 provided in a further template mounted alongside the direction of longitudinal travel of the table. The peg is located to one side of the direction of longitudinal travel so as to exert a turning moment on the second table 42 so that it continues to turn in a generally clockwise direction (in the example shown in the figure) particularly at the beginning and end of the sealing operation. The shape of the slot 104 will be varied to suit the exact contour of shoe sole being seam-sealed. Thus, in the initial stage (shown in full lines) the second table is angled to the forward direction as shown to enable seam sealing tape to be applied starting from the toe region of the shoe. On further forward travel the action of the peg in the slot rotates the table to the straight position (shown in dashed lines) where tape is applied along the sides of the shoe. Finally, the last forward travel movement rotates the table 42 clockwise again so as to apply tape around the heel region.

In a further embodiment, the table may be rotated by

appropriately choosing the profile of template 48.

Alternatively to rotation of the table, provision may be made for rotating the tape applicator assembly 34 around an upright axis. This may be done manually or automatically.