MOLDED SOLE SHOE ASSEMBLING DEVICE

Description

Molded Sole Shoe Assembling Device

Technical Field

The present invention relates to a device useful in the assembling of molded shoe soles to shoe uppers. The present invention also relates to a method for using such a device.

Background Art

In the manufacture of shoes having molded soles, it is conventional to place a prefabricated shoe upper onto a mold element called a "last" in preparation for the molding of the shoe sole onto the upper. Conventionally, three such lasts are mounted for rotation into at least three positions corresponding to operations to be performed in shoe molding. In a first position, the shoe uppers are placed on the last and tightened about the last. In particular, a flap of the upper is tightened onto the sole of the last, so that the sole can be molded onto a taut upper. For this purpose, it is conventional to provide last strings in the flap of the upper, which last strings can be pulled to tighten the upper onto the last. Once pulled, the last strings remain tight due to friction.

However, repeated tightening the last strings on an industrial scale poses a significant health problem.

Workers manually tightening the last strings are subject to various physical stress related injuries, e.g., as carpal tunnel syndrome, and so it is desirable to automate the last string pulling step.

A last string puller is known from U.S. Patent 3,778,856 (Christie et al) in which a bobbin is mounted on a fluid cylinder for pulling the last strings. There, the last strings are wound about the bobbin in such a way that they are tightly gripped by the bobbin. Upon retraction of the bobbin by a fluid motor, the last strings are pulled and tightened. However, Applicant has discovered that a device which tightly grips the last strings and tightens the same is not practical on an industrial scale since it tends to break the last strings during tightening. The uppers having broken last strings must be removed from the last and discarded.

Before rotating the last to the second position, i.e., the sole molding position, it is also necessary to pull in the upper around the instep. Conventionally, this is done by manually hooking the upper on the last. However, again, repeated manual operations caused physical stress related injuries in workers performing this duty.

Following the molding of the sole onto the upper, the last is rotated from the second position to a cooling position in which both it and the sole are permitted to cool. For this purpose, it has been known to provide internal cooling circuits within the last.

Finally, the last returns to the first position in which the shoe having the sole molded thereon is to be removed therefrom in preparation for a subsequent operation. However, since the upper has been tightly applied to the last, shoe removal again causes various physical stress related medical problems for workers required to repeatedly and forcefully remove the shoes from the last. Disclosure of the Invention

It is an object of the present invention to provide a method for tightening the last strings of shoe uppers mounted on a last with reduced danger of breaking the last strings.

It is a further object of the present invention to provide a method for hooking a shoe upper mounted on a last onto the sole pins of the last.

It is a further object of the invention to provide a shoe last having a flow circuit outlet portion which aids in removing a shoe from the last.

It is yet a further object of the invention to provide a method for molding a shoe sole onto a shoe upper, including using high pressure gas exiting the last to aid in removing the shoe from the last.

According to one feature of the invention, the above and other objects are accomplished by a method for tightening the last strings of a shoe upper mounted on a last, in which the method includes the steps of positioning a bobbin of a string puller such that the last strings may be wound around the bobbin, winding the last strings around the bobbin, and moving the string puller in a direction parallel to the sole of the last such that the bobbin tightens the last strings, while manually gripping the ends of the last strings.

According to the invention, the manual gripping tension on the ends of the last strings is modulated during the moving step such that a frictional force between the last strings and the bobbin is limited to such a value that the last strings are not broken. According to a further feature of the invention, a method for pinning a shoe upper mounted on a last onto sole pins of the last includes the steps of grasping the upper by teeth mounted on a fluidic cylinder system, operating the fluidic cylinder system in a first operating step such that the teeth move toward one another. Simultaneously with the first operating step, the fluidic cylinder system is operated to raise the upper away from the last and over the last pins. After this second step, the fluidic cylinder system is operated to lower the upper toward the last after the upper has moved over the last pins. This results in the upper being pinned by the last pins.

According to a further feature of the invention, a shoe last includes a last body having a toe portion, and internal flow circuit in the last body for passage of a cooling fluid, and means for selectively connecting the internal flow circuit to a source of high pressure gas. A flow circuit outlet portion of the flow circuit is formed at the toe portion. As a result, the high pressure gas exiting the flow circuit at the toe portion can aid in removing a shoe from the last.

According to yet a further feature of the invention, a method for molding a shoe sole on a shoe upper includes the steps of mounting the upper onto a last having an internal flow circuit for passage of a cooling fluid and molding a sole onto the upper mounted on the last. The sole and last are cooled by flowing a cooling fluid through the circuit, after which the removal of the shoe from the last is aided by flowing a high pressure gas through the circuit and out of the outlet portion of the internal flow circuit. Brief Description of the Drawings

A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

Figure 1 is a front view of an apparatus according to the present invention;

Figure 2 is a side view of the apparatus of Figure i;

Figure 3 is a front view of the last string puller of the apparatus of Figure 1;

Figure 4 is a side view of the last string puller of Figure 3;

Figure 5 is a front view of one the pinning devices of Figure 1;

Figures 6A-6C schematically show three phases of the operation of the pinner of Figure 5;

Figure 7 is a partial side view of the apparatus of Figure 2; and

Figure 8 is a section through cut 8-8 in Figure 7. Best Mode for Carrying Out the Invention

Referring to the Figures, wherein the same reference numerals are used to refer to the same elements throughout the several views, a base 2 supports a lower mold 4 and a last support head 6. The lower mold 4 is entirely conventional and will not be further described, beyond noting that it includes recesses for holding sole material, such as raw rubber, for soles to be mounted on the shoe uppers, as well as heating elements for curing the molded sole.

The last support head houses a motor (not shown) which may be a fluid motor which drives shafts 8 upon which the rotary bases 10 for the lasts are mounted. The rotary basis each support, e.g., three last 12 which are angularly spaced from one another by 120°. A fluid control system (not shown) for the motor mounted within the last head 6 controls the motor so as to sequentially rotate each of the lasts to a first position indicated as 12A in Figure 2, a second or molding position indicated as 12B in Figure 2, and a third or cooling position indicated as 12C in Figure 2. The above construction is well known in the art and will not be described in detail herein.

A shoe upper is mounted to the last at the position 12 . Conventionally, the shoe uppers are prefabricated with flaps that fit over the sole of the last. The flaps contain last strings which must be pulled tightly for securing the shoe upper on the last with the flaps covering the last sole, in preparation for the sole being mounted on the shoe upper. The present invention therefore incorporates a last string puller such as that shown in Figures 3 and 4. For each last rotating base 10, there is provided a last string pulling motor 16. Each last string pulling motor 16 includes a pneumatic cylinder 18 mounted to the last support head 6 and having a rod 20. A bobbin bracket 22 is mounted to the end of the rod 20. The bracket 22 may be formed of L-shaped stock having smoothly rounded ends 24 and 26. On one face of the bracket is mounted a bobbin 28. The bobbin 28 may be cylindrical, but may also have the illustrated hour-glass shape or any other shape which aids in the retention of the string thereon.

Bracket 22 can be moved by the cylinder 18 between a retracted position 22A, an intermediate position 22B and an extended position 22C. The control of pneumatic pressure to the pneumatic cylinder 18 is applied by the foot pedal air valves 24 (Figures 1 and 2) . Pressing on one of the foot pedal air valves applies lower pressure compressed air to the cylinder 18 for advancing the bracket to the intermediate position 22B, while pressing on the other of the foot pedal air valves 24 applies higher pressure compressed air to the cylinder 18 for advancing the bracket to the extended position 22C.

The air cylinder 18 is oriented so that the rod 20 thereof extends in a direction substantially parallel to the sole of the last in the position 12A.

For tightening the last string, the shoe upper 30 is first mounted on to the last 12 while in the position 12A. Subsequently, an actuation of the appropriate foot pedal air valve causes the air cylinder 18 to advance the bracket 22 from the retracted position 22A to the intermediate position 22B. The last strings 32 are then loosely wound about the bobbin 28 one or two times in preparation for tightening. Subsequently, foot actuation of the appropriate foot pedal air valve 24 applies higher pressure air to the cylinder 18 for causing the bracket to be advanced from the intermediate position 22B to the extended position 22C. As this occurs, the last strings 32 tighten around the rounded end 26 of the bracket, and also around the bobbin 28.

A critical feature of the present invention is that the maximum pulling force on the last strings is modulated by manually modulating the gripping tension on the ends of the last strings as the bracket 22 moves from the intermediate position 22B to the extended position 22C It is well understood that the frictional force between the last strings and the bracket end 26 and bobbin 28 is related to and the string tension. Thus, if one simply loosely winds the last strings once about the bobbin 28 and releases the last strings prior to the advance of the bracket 22 to the extended position 22C, the last strings will not be tightened. On the other hand, if one winds the last strings on the bobbin 28 by numerous turns, or overlaps one or more of the turns of the last strings so that a turn is tightly gripped between the bobbin and another turn, there will be no "give" in the gripping of the last strings by the bobbin. Therefore, should the pulling force of the cylinder 18 exceed the tensile strength of the last strings, they will break during the advance of the bracket to the extended position 22C.

According to the present invention, the operator only winds the last strings about the bobbin 28 by one or two turns. However, the operator retains manual tension on the ends of the last strings 32. For example, the operator can hold the last strings between the thumb and first finger, and modulate the manual gripping tension by adjusting the pressure between the thumb and first finger. As the bracket 22 is advanced to the extended position 22C, the degree by which the last strings are tightened on the bobbin is a function of the manually modulated gripping tension at the ends of the last strings. In turn, the frictional gripping force of the bobbin 28 and bracket edge 26 on the last strings is a function of such string tightening. One can therefore fairly precisely regulate the maximum pulling tension on the last strings simply by modulating the manual gripping tension on the ends of the last strings during the movement of the bracket to the extended position 22C. This procedure can be repeatedly performed on an industrial scale with reduced risk of injury to the operator, since the pulling tension is applied by the air cylinder 18, and not by the operator; rather than supplying pulling tension, the operator simply modulates the limit of string tension.

Once the last strings have been pulled, it is still necessary to tighten or pull in the shoe upper onto the last in the region of the instep. For this reason, the last is provided with pins 34 extended substantially perpendicularly from the last sole in the region of the instep. The portion of the upper adjacent the last strings should be hooked onto (inside of) the last pins 34. For this purpose, a pinner jaw 36 is supported on an adjustable base 38 mounted to the base 2 (Figure 5) . Each adjustable base can be of a conventional construction and comprise a case supporting a pair of perpendicular advancing screws having handles 40 and 42 for adjusting pinner arm 44 mounted on the adjustable base in two orthogonal directions. A further pinner arm 46 is pivoted to the top of the pinner arm 44. A pinner arm cylinder 48 has a lower end mounted to the pinner arm 44. The cylinder rod thereof is pivoted to the pinner arm 46 so that cylinder 48 can pivot the pinner arm 46 to raise and lower the same.

Mounted to the pinner arm 46 is a pinner jaw clamping cylinder 50 which supports a pair of pinning teeth 52. One of the pinning teeth is mounted directly to the cylinder 50 while the other is mounted to the rod thereof, so that the spacing between the pinning teeth 52 toward one another can be adjusted.

The pinner arm 46 also supports a pinner lifting cylinder 54. The rod of the pinner lifting cylinder 54 supports a sole block 56 having guide structure 58. Fluid conduits such as 60 provide pressurized air to the cylinders 48, 50 and 54 for operating the same according to a predetermined control sequence. The control circuitry may be entirely conventional and preferably comprises solenoid operated valves for each of the cylinders 48, 50 and 54, timing of each of the solenoid operated valves being controlled by a programmed general purpose controller (not shown) .

In operation, the base 38 is adjusted to the specific dimensions of the last and last pins associated therewith. Prior to the placement of the shoe upper on the last, pinner arm 46 is kept retracted by the cylinder 48 to the position shown in Figure 1, so that it does not interfere with the last string pulling sequence described above. Following the completion of the last string pulling sequence (which can be detected by the pinner controller by, for example, detection of the retraction of the cylinder 18 back to the position 22A) , the cylinder 48 is operated to lower the pinner arm 46 to the position shown in Figure 5. Subsequently, the cylinder 50 is operated to advance the pinner teeth 52 toward one another so that they are able to hook upper in the region of the last strings in preparation for subsequent operations.

Following the hooking of the upper by the pinner teeth (Figure 6A) , the pinner lifting cylinder 54 is operated to lower the sole plate 56 onto the last sole and press downward onto the last sole. The resulting reaction force slightly raises the pinner arm 46 and the pinner teeth 52 mounted thereto, while pushing down on the last. Further contraction of the cylinder 50 causes the pinner teeth to move further toward one another (Figure 6B) so that the upper is raised up, and hooked over, the last pins 34. The hooking operation has now been completed and the pinner teeth can be separated while releasing the pressure on the sole plate 56 (Figure 6C) . The arm 46 can then be raised to the position of Figure 1.

The sole, having the shoe upper mounted thereon and hooked over the last pins 34, is then rotated to the position of 12B where a conventional molding operation takes place. Following molding, the last is rotated to the position 12C for cooling. Referring to Figure 7, the lasts have internal cooling circuits 70 and 72. The circuit 70 applies cooling fluid to the last heel while the circuit 72 extends parallel to the last sole and forward to the last toe. A heel outlet for the cooling circuit 70 is normally closed by a spring loaded plunger 72 while the last circuit 72 terminates at a toe orifice 76 which is normally open. A groove 78 communicates with the toe orifice 76 and extends along the toe to provide a passage for the cooling fluid which exits the toe orifice 76.

Each of the cooling circuits 70 connects to a fluid hose 80 at connection 82. The fluid hoses in turn connect to a rotary valve 84 which selectively supplies cooling fluid to the hoses 80 as a function of the rotary position of the last. For example, the rotary valve 84 can comprise a stationary disc 86 mounted concentric with the shaft 8, and on an extension 87 of the last support 10. The hoses 80 connect to the rotating extension 87 at angular positions separated by 120°. The extension 87 has a flange 89 which forms a rotary joint to hold the disc 86 for rotation on the extension 87.

A high pressure line 88 and a low pressure line 90 connect to the disc 86 so that the low pressure line 90 is in communication with the hose 80 for the last in position 12C while the high pressure line 88 is in communication with the hose 80 for the last just before it reaches the position 12A.

Low pressure air in the line 90 is cooled and humidified in the in line water filled oiler 92. The cooled and humidified air then passes through the line 90 to the hose 80 for the last 12C via the rotary valve 84 and ultimately reaches the cooling circuit 70 of that last. The pressure of the low pressure air is insufficient to open the valve 74, and so the cooling air flows through the cooling circuits 70 and 72, and exits the toe orifice 76 for cooling the last.

Ideally, the pressure of the air in the line 90 should initially be very low so as to prevent the air pressure from popping the still soft sole off of the upper. The air pressure can then gradually increase to promote rapid cooling.

Subsequently, as the last is rotated back toward the position 12A, the conduit 80 for that last is briefly rotated into intercommunication with the high pressure air line 88 just before the last reaches position 12A. The high pressure air therefrom enters the cooling circuits 70 and 72 and opens the plunger valve 74. The high pressure air exiting the plunger valve and the toe orifice provide a pneumatic assist for the operator in removing the shoe from the last.

Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practices otherwise than as specifically described herein.