GB2174950A - Apparatus for the direct soling of shoe uppers - Google Patents

Abstract

An apparatus for the direct soling of shoe uppers comprises a set of moulding stations and an injection unit. The injection unit includes a mixing chamber provided with a screw 10 which can be changed automatically. In order to permit the screw 10 to be camped and released quickly, the screw 10 is mounted on a spindle 7 constructed as an expandable mandrel. The spindle 7 has an expandable sleeve portion 28 for clamping the screw 10 and a piston 32 for pressurizing the fluid which causes the portion 28 to expand. Piston 32 is loaded by a spring 36 and unloaded by a cylinder unit 40 which drives a dog element 42 which engages the end of piston 32. <IMAGE>

Description

SPECIFICATION Apparatus for the direct soling of shoe uppers The invention relates to apparatus forthe direct soling of shoe uppers comprising a single moulding station or a set of moulding stations arranged in a row or on a circular line, and at least one displaceable injection unit having a mixer head which is provided with a screw.

In the shoe manufacturing industry the expression "direct soling" is used forthe automated fabrication of soles accompanied by simultaneous attachment thereof to the uppers. This is preferably done by injection moulding. Suitable materials forthe uppers are, for example, leather, textiles or synthetic materials and, forthe soles, polyvinylchloride, nylon, granulated polyurethane and liquid components of polyurethane or thermoplastic rubber. The materials for sole fabrication are preferably injection moulded in closed moulds.

Machines for the direct soling of finished shoe uppers are known in the art. Particularly well known are turntable or revolving table systems which comprise, for example, 18 moulding stations on the worktable. During each revolution ofthetable,the moulding stations are driven in turn in successive operating cycles into the axis of an injection unit. The injection unit approaches each moulding station in turn in orderto mouldasoledirectlyon to an upper.

For multipart or multicoloured soles, two injection units are provided and these are relatively angularly staggered around the circumference of the work table.

The injection unit is driven by a transport cylinder into the correctworking position infrontofthe mould. When the injected material can no longerflow from the orifice of the injection unit, the unit is driven back to its retracted position and, in the case of a revolving table system, this triggers the next operating cycle.

An injection unit comprises an injection nozzle, a mixer head, a screw and pumps. The mixer head comprises a housing and the screw and associated screw mounting and bearings. The mixer head and the screw mounting are arranged in a stationary manner on the injection unit.

When working with liquid polyurethane, for example, two liquid components are used and these are supplied by metering pumps. For each component a separate valve is provided on the mixer head. The two components must be very intensively mixed together. This is done inside the so-called mixing chamber by the screw. Preferably the front part of the mixing chamber is of conical configuration and the rear part is of cylindrical configuration. The mixer screw has a corresponding configuration. The screw rotates at approximately 15,000 to 18,000 RPM.

The gap between the outer contours ofthe screw and the inside contours ofthe mixing chamber is adjustable. The size of the mixing gap is approximately 0.5 to 1.5 mm.Thescrewis subsequently horizontally displaced inside the mixer head to such an extent thatthe mixing gap is reduced to only 0.1 mm. The axial displacement of the screw is applied by a screw-advancing cylinder. The high speed of rotation of the screw and the pressure head created by the tapering of the mixing chamber ensure that the components inside the screw are very intensively mixed together.

Besides this, the mixtures is transported into the injection mould by the conveyor action of the screw.

When the mixing process is completed the valves are closed. In this cleansing position the screw will clean itself up due to the high centrifugal forces involved.

However, the known injection units according to the state of the art have the drawback that they only allowfora manual screw change. In orderto dothis, the screw is extracted from the front of the mixer head after unscrewing the nozzle.

When working with polyurethane as an injection component, a screw change may be necessary every 11/2 to 2 hours because of material accretions in the turns ofthe thread of the screw. These accretions progressively inhibit and eventually prevent intimate mixing ofthecomponents. Not only does this operation entail a considerable loss of time but it also requires the presence of an operator so that this manual procedure is altogether fairly cost intensive.

It is an object of this invention to provide an apparatusforthe direct soling of shoe uppers which permitsthescrewto be clamped in position and released in a short period.

According to this invention there is provided an apparatusforthedirectsoling of shoe uppers comprising a single moulding station or a set of moulding stations arranged in a row or on a circular line and at least one displaceable injection unit, the or each injection unitincluding amixerhead,ascrewfor the mixing head positioned on an expandable mandrel, and an operating piston for the mandrel and which is loaded by a resilient biasing force and relieved byan unloading device.

Hydraulically operated expandable mandrels as such are known, for example in machining work.

However, these known constructions have the disadvantagethattheclamping and releasing ofthe tool is performed with the aid of a manually operated chuckandthis precludes fully automated operation.

The invention has the advantage of providing an essential contribution towards the development of a fully automated screw-changing device. An automated screw-changing device requires both a manipulating system for transporting the screws and an arrangementforclamping and releasing the screws. The present invention allows both release of the screw from the driving spindle as well as clamping of the screw on the spindle within the shortest possible time. The result is a considerable saving in time and costs. In otherwords, the present invention represents a further important step towardsfully automatically operating machinery.

The time required for a screw change can be fed into the machine control program. The system is subject to a break in the normal working cycle for at most 1 minute and then automatically carries on with production. This advantage becomes particularly apparent if one considers that a manual screw change may take up to about 25 minutes. The invention provides an arrangement of very robust construction which is capable of fast operation.

When the invention is incorporated in an automated apparatus in which the interval between screw changes cannot exceed a preset period, a constant quality of the injection moulded article is guaranteed.

This invention will now be described in more detail, byway of example, with reference to the drawings in which: Figure 1 is a side view of a revolving table system embodying this invention; Figure 2 is a simplified side view showing the screw in its retracted position in which the screw can be fitted or removed; and Figure 3 is a simplified view of the expandable mandrel and the associated unloading device.

In Figure 1 there is shown a revolving table system comprising a revolving table 1 rotatably mounted on a stand 2. Individual moulding stations 3 are arranged on the outside ofthe table 1. An injection unit is shown at 4 and a material container station at 5. The revolving table 1 supports the moulding stations 3 at positions spaced around its outer periphery. Such a revolving table may be fitted with,for example, 18 moulding stations. The control console and temperature control system are not individually numbered. The material container stationS consists oftwo containers 5 when polyurethane is injection mouldedfrom two components. If a third component is added the station will have a third container.

A revolving table system of the kind generally comprises one injection unit 4. For multi-layered soles two injection units4will be provided. However, in that case the section unit will be constructed in like mannerto the single unit shown in Figures 1 and 2.

Figure 2 shows the injection unit4 in the position in which a screw 10 can befitted or removed.Thus, Figure 2 shows a mounting 6forscrew 10 in a retracted position. The screw mounting 6 may also be called a screw bearing. Inside this screw mounting 6 is a spindle 7 which is driven, e.g. via a transmission belt9, by a motor8. The screw 10 is secured to this spindle 7. In the operational state of the screw 10, it is driven to the left hand side into a mixing or injection position. In this position the screw 10 rotates in a mixing chamber 11 which is provided in a mixer head 12. The reference number 13 indicates valves for feeding components into the mixing chamber 11.

A feed cylinder 14 is secured to the screw mounting 6 and drives the screw mounting 6 eitherinto retracted position, as shown in Figure 3 or into the mixing or injection position. In this latter position, the screw mounting 6 is driven into the left hand end position thereof, but this is not illustrated.

In the base of the injecting unit4there is a stand 16 on which is mounted a magazine 17 forthe screws 10.

This magazine 17 is constructed as aturret head provided with circumferentially spaced recesses 18 into which the screws 10 are radially introduced. The magazine 17 is rotatable about a vertical axis 19.

The operations oftransporting the screws 10, inserting them into the screw mounting 6, removing them from this mounting 6 and inserting them into or extracting them from the magazine 17 are carried out by a gripping device 20. The gripping device 20 is driven between two end positions by a hydraulic cylinder 21.These two positions are an upper position in which a screw 10 may be clamped or released by the screw mounting 6 and a lower position in which screws 10 may be deposited in or with drawn from the magazine 17.

The gripping device 20 is driven to the leftorright hand side by a hydraulic cylinder 22. This movement is necessary to enable the gripping device 20 to put a screw 10 onto the screw mounting 6 or into the magazine 17 orto retrieve it therefrom.

The magazine 17 can accomodate on its circumference a number, for example 8, of screws.

The magazine 17 may be provided, for example, with a stepping motor allowing the individual screws to be driven into position successively so that the gripping device 20 can pick them up or redeposit them.

However, this stepping motorforthe magazine 17 is not shown in the drawings.

The screw mounting 6 is connected to the hydraulic cylinder 14 is by a piston rod 23. A piston rod of the hydraulic cylinder 21 for gripping device 20 is shown at 24 and a piston rod 25 of the hydraulic cylinder 22 is used forthe axial displacement of the gripping device 20, particularly during the insertion of a screw 10 onto the screw mounting 6 or its removal therefrom as well as during depositing a screw 10 in magazine 17 and extracting it therefrom.

Reference number 26 designates the so-called cleaning cylinder. This conducts a screw 10 into the above described cleaning position in the mixing chamber 11.

Afeed cylinder 27 serves to drive the entire mixing unittowardsthe moulding station.

If a screw 10 isto be changed in a very short time, it isveryimportantthatit must be arranged so asto be also very quickly clamped or released. The arrangementfor doing this is shown in detail in Figure 3.

The spindle 7 is constructed as a so-called expandable mandrel mounted in bearings 39 inthe screw mounting 6. The expandable mandrel 7 has a thin-walled sleeve portion 28 which forms a clamping orchuck portion on the mandrel forscrew 10. A circumferential slot 29 creates the thin-walled sleeve portion 28. A pressure fluid is introduced into this slot 29 so that the sleeve portion 28 will be expanded thereby and due to such expansion will tightly grip the screw 10.

The pressurized fluid is fed through a central passage 30 and a cross passage 31. The pressure is generated by piston 32 which is provided with two seals 33 to preclude asfar as possible anyescape of hydraulic fluid to the exterior.

This piston 32 has a shoulder 34 and between this shoulder34and athreadedsleeve nut35adaptedto be screwed on there is arranged a spring 36which loads the piston 32 with a resilient biasing force thereby causing the piston 32 to generate the pressure in the hydralicfluid. The sleeve nut35 functions to load spring 32 and is screwed onto a sleeve 37 of which the front part is constructed as a drive pinion 38. The drive pinion receives drive torque (forexamplevia V-shaped transmission belt, not shown) and this drive torque is transmitted to the screw 10. The spring 36 is preferably composed of a set of plate springs because these may have a relatively small diameter and still provide a very high spring force which will then result in a very high gripping or clamping force forthe screw 10.Provided the spring 36 is not released, it will therefore apply a continuous spring forceto the piston 32which therefore applies a continuous pressure to the hydraulic fluid.

For dismantling the screw 10from the expandable mandrel it is necessary to cancel the force of spring 36 thereby relieving piston 32. This may be done, for example, by displacing piston 32 so as to compress spring 36. Then the hydraulicfluid is no longer subjectto pressure and the expandable sleeve portion 28 is no longer expanded so that the screw 10 merely requires pulling off the mandrel in its axial direction.

Pressure reliefforthe hydraulicfluid may be obtained, for example, by means of an unloading device comprising a cylinder unit 40 from which extends a piston rod 41 and which carries a dog element 42 whereby the piston 32 is displaced in opposition to the force in spring 36. The cylinder unit 40 may be a pneumatically oran hydraulically operated cylinder unit. The dog element 42 may engage piston 32 directly or a piston rod connected to piston 32.

Alternatively the operations of damping and releasing the screw may be carried out with the aid of a mechanically actuated expandable sleeve.

Although the present invention has been described in the above embodiment with reference to the revolving table system, it is not confined to such system. For example, the present invention may be applied to a system having a single moulding station or a set of moulding stations arranged in a row.

Claims (8)

1. An apparatus for the direct soling of shoe uppers comprising a single moulding stations arranged in a row oron a circular line and at leastone displaceable injection unit, the or each injection unit including a mixer head, a screwforthe mixing head positioned on an expandable mandrel, and an operating piston for the mandrel and which is loaded by a resilient baising force and relieved by an unloading device.

2. An apparatus as claimed in claim 1 in which the biasing force is provided by a set of plate springs.

3. An apparatus as claime in claim 2 in which the set of plate springs are assembled between a shoulder formed on said piston and a sleeve unit.

4. An apparatus as claimed in claim 3 in which the sleeve nutfunctionsto load the set of springs.

5. An apparatus as claimed in any one of claims 1 to 3 in which the unloading device is arranged to operatively engage said piston or a piston rod connected to said piston.

6. An apparatus as claimed in claim Sin which the unloading device comprises a pneumatically or hydraulically actuated cylinder unit having a piston rod and a dog element secured to the piston rod ofthe cylinder unit, said dog element operatively engaging the mandrel operating piston orthe piston rod connected to the mandrel operating piston.

7. An apparatus as claimed in claim Sin which the application of pressure to the pneumatically or hydraulicaly actuated cylinder unit causes the mandrel to release the screw.

8. An apparatusforthe direct soling of shoe uppers substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.