GB2311952A

GB2311952A - Improved blank feeding unit for a coining press

Info

Publication number: GB2311952A
Application number: GB9605575A
Authority: GB
Inventors: Charles Ian Ridgway; Julian Heyworth
Original assignee: Joseph Rhodes Ltd
Current assignee: Joseph Rhodes Ltd
Priority date: 1996-03-16
Filing date: 1996-03-16
Publication date: 1997-10-15
Anticipated expiration: 2016-03-16
Also published as: WO1997034773A2; GB2311952B; EP0827459A2; GB2311952A8; WO1997034773A3; GB9605575D0

Abstract

A coining press (10) which comprises an indexable feed plate (11) having a number of circumferentially spaced blank-receiving recesses (12) in its periphery, a coining tool (13) arranged at a forming station (14) adjacent to the periphery of the feed plate, and a blank feed unit (15, 16) arranged at a feeding station adjacent to the periphery of the feed plate and circumferentially spaced from the forming station, in which the blank feed unit comprises a stacking device for receiving a stack of coin-forming blanks and a feeding device engageable successive with the instantaneously lowermost blank of the stack to feed the latter into an adjacent blank-receiving recess in the periphery of the feed plate, and the press being characterised by: an electrically operable driving device coupled with the feeding device to operate the latter between a retracted position and an extended position in order to move the lowermost blank into a respective recess in the feed plate; and, a control arrangement connected to the driving device and arranged to monitor the operation of the press so as to operate the electrically operated driving device in synchronism with the operation of the press.

Description

IMPROVED BLANK FEEDING UNIT FOR A COINING PRESS This invention relates to a coining press which comprises an indexable feed plate having a plurality of circumferentially spaced blank-receiving recesses in its periphery, a coining tool arranged at a forming station adjacent to the periphery of the feed plate, and a blank feed unit arranged at a feeding station also adjacent to the periphery of the feed plate and circumferentially spaced from said forming station.

In a typical existing design of vertically operating coining press, a blank feeding unit feeds the coin blanks to a dial feed plate, and which indexes the blanks successively to a coin-forming tool arranged adjacent to the periphery of the feed plate. The coining press is of the upstroking type, and when the usual press slide is in the "down" or bottom dead centre position, it remains stationary or "dwells" for approximately one third of the press cycle. This dwell period allows the dial feed plate to index through the coin forming station, whereby to remove a minted or coined blank from the press slide and to replace it with a fresh coin blank.

During the remaining part of the press cycle, when the dial feed plate is stationary, a new coin blank will be loaded into one of the empty dial plate stations, ready to be indexed to the slide or coining area. Coin blanks are usually fed from a bowl-type feeder (mechanical or vibratory) and into a vertical stacking tube which forms a vertical stack of coin blanks.

A blank feed unit co-operates with the stack of blanks, and usually has a "pusher finger" driven by a swash plate cam arrangement, and which moves from a withdrawn (retracted) position relative to the periphery of the feed plate to an extended position of engagement with the outer periphery of the feed plate, whereby the pusher finger pushes out the lowermost blank in the stack from beneath the stack and into one of a series of blank-receiving recesses circumferentially spaced around the periphery of the feed plate.

The drive to the pusher finger e.g. a swash plate cam, derives its power input via a direct mechanical linkage or coupling between the press and the blank-feeding system. The swash plate type of cam mechanism to operate the pusher finger is prone to rapid wear, and particularly at high speeds, and other drive mechanisms conventionally employed e.g. a conventional crank mechanism, is less suited to high feed rates. Regardless of the mechanical device employed with existing machines to move the blanks into engagement with the recesses in the periphery of the feed plate, there is a tangible mechanical link between the press and its feed system.

By contrast, the present invention proposes to eliminate a direct mechanical feedback from the operation of the press to the blank feeding unit, with its attendant disadvantages, and relies upon a means of monitoring the operation of the component parts of the press which provides non-mechanical feedback to control the speed and timing of operation of the blank-feed unit.

According to the invention there is provided a coining press which comprises: an indexable feed plate having a plurality of circumferentially spaced blank-receiving recesses in its periphery; a coining tool arranged at a forming station adjacent to the periphery of the feed plate; and a blank feed unit arranged at a feeding station also adjacent to the periphery of the feed plate and circumferentially spaced from said forming station, said unit comprising a stacking device for receiving a stack of coin-forming blanks, and a feeding device engageable successively with the instantaneously lowermost blank of the stack to feed the latter into an adjacent blank-receiving recess in the periphery of the feed plate, in which: an electrically operable driving device is coupled with said feeding device to operate the latter between a retracted position and an extended position in order to move the lowermost blank into a respective recess in the feed plate; and, a control arrangement is connected to said driving device and is arranged to monitor the operation of the press so as to operate the electrically operated driving device in synchronism with the operation of the press.

The invention therefore eliminates the conventional direct mechanical feedback from the press to the blank feeding unit, and provides a means whereby the feed unit can automatically be adjusted in its speed and timing of operation to keep in step with the (intermittent) operation of the press, and regardless of the overall speed of the operating cycle of the press.

Preferably, the feeding device comprises a feed finger, drive by a crank mechanism having a very short coupling length, which facilitates significant changes in acceleration during the motion profile, such mechanism being driven by an electric motor whose initiation, and speed of operation is controlled by said control arrangement which monitors the operation of the press.

The crank drive mechanism to the feed finger may be configured so as to create, effectively, a "dwell" of the finger, and which allows an increased time for the next blank in the stack to drop into place, prior to being pushed into the next receiving recess in the periphery of the feed plate.

The crank mechanism is therefore advantageously developed specially so as to provide required motion profile, and is driven by an electric motor, whose initiation and speed of operation is effected via said control arrangement.

In a preferred arrangement, the control arrangement comprises an encoder arranged to be driven by the press, thereby eliminating the more conventional mechanical link between the press and feed system. The electric motor and the encoder not only enable the feed system to keep in step with the press at all operating speeds, but also allows the rate of speed to be varied during each cycle so that the blank-feeding unit operates entirely in synchronism with the operation of the press, but furthermore (providing the overall time for each complete cycle is not changed) it can effect the best conditions for feeding each size of coin blank.

In a particularly preferred embodiment of the invention, two separate blank-feeding units are arranged at circumferential spacings relative to the periphery of the feed plate, and this can allow composite coins to be formed from more than one coin blank. By providing two separate blank feeding units, this provides an increase in flexibility of the coining press, and makes it ideally suited to the feeding of shaped coin blanks, bi-metallic (non-homogeneous) coin blanks, and large diameter (homogeneous) blanks. Existing feeder mechanisms have problems in dealing with such blanks, particularly where frequent denomination change-overs are required. However, by the inclusion of two blank feeding units on the press, and each driven by a respective electric motor synchronised to the operation of the press through an encoder, the system can be configured so as to feed in sequence and at the same frequency as the press operating speed, or at half press speed to feed into alternate dial plate stations. The former would then allow the feeding of bi-metallic blanks, comprising a separate "outer", and a separate "inner", and the latter, (providing the two feeder unit stations are placed an "odd" number of recessed indexes apart), the feeding of the more difficult shaped or large diameter blanks.

It is the combination of the specially developed mechanism, and the ability to control the rotational speed of the or each electric motor within each cycle, which affords the best conditions for the feeding of each particular blank.

A further advantage is that any of these modes are selected simply by an electrical switch. A preferred embodiment of coining press according to the invention will now be described in detail, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic plan view of a coining press, having a dial type feed plate, a coin-forming station and first and second blank feeding units arranged at circumferentially spaced stations relative to the outer periphery of the feed plate; Figure 2 is a side view corresponding to Figure 1; and, Figure 3 is a graph of a motion profile of each blank feeder unit relative to the operating cycle of the press.

Referring now to Figure 1 and 2 of the drawings, a preferred embodiment of the invention has first and second blank feeding units arranged at circumferentially spaced feeding stations relative to the outer periphery of a dial feed plate. There is also a circumferentially spaced coining station. However, it should be understood that this is a preferred arrangement only, and that the invention contemplates, when required, use of a single blank-feeding unit only at a suitable feeding station.

A coining press according to the invention is designated generally by reference 10 and comprises a horizontal indexable feed plate 11 i.e. a so-called dial feed plate, and which has a plurality of circumferentially spaced blank-receiving recesses 12 in its periphery. A coining tool 13 is arranged at a feeding station 14 adjacent to the periphery of the feed plate 11, and a first blank feed unit 15 and a second blank feeding unit 16 are arranged at respective feeding stations 17 and 18 respectively, circumferentially spaced from each other, and also circumferentially spaced from the forming station 14.

Each feeding unit 15, 16 comprises a stacking device in the form of a vertical column 19 which receives a vertical stack of blanks 20 from a suitable supply device, which in the illustrated arrangement comprises a known bowl feeder 21. Each unit has a feeding device engageable successively with the instantaneous lowermost blank 20 of the stack, to feed the latter into an adjacent blank-receiving recess 12 in the periphery of the feed plate 11. In the illustrated embodiment, the feeding device comprises a linearly movable feed finger 22 which is movable between a retracted position, and an extended position in order to move the lowermost blank 20 of the stack into the respective recess 12 in the feed plate.

Any suitable mechanical drive mechanism is coupled with the feed finger 22, in order to apply linear reciprocation to it, and in the illustrated embodiment this comprises a specially designed crank mechanism 23 having an extremely short coupling length, which facilitates significant changes in acceleration of the feed finger 22 during the motion profile.

This is configured so that effectively the finger can "dwell", and allow an increased time for the next blank in the stack to drop into place, prior to being pushed into the next recess 12 in the feed plate 11 upon indexation of the latter.

An electrically operated driving device is therefore coupled with the blank feed device (feed finger 22) and operates the latter between the retracted position and the extended position in synchronism with the timing and speed of operation of the press. Therefore, an electric motor 24 is coupled with crank mechanism 23, and the initiation of operation of the motor, and its speed of operation, is controlled by a non-mechanical type of control arrangement which monitors the operation of the press, whereby to operate the driving device (23, 24) in synchronism with the operation of the press.

Although not shown, the control arrangement comprises an encoder driven by the press, and which initiates commencement, stopping, and controls the speed of operation of the motor 24 in exact correspondence with the operating cycle of the press.

The embodiment of the invention thereby eliminates the more conventional direct mechanical link between the press and the blank feed system. The electric motor and encoder not only enables the feed system to keep in step with the press at all operating speeds, but also allows the motor speed to be varied during each cycle (providing the overall time for each complete cycle is not changed) to effect the best conditions for feeding each size of coin blank.

The coining tool at the forming station 14 can be of conventional construction, being of an upstroking type, and the construction and operation of the coining tool will be well known to those of ordinary skill in the art, and need not be described in detail herein.

As indicated above, the preferred embodiment has first and second blank feeding units, and this gives flexibility to the operation of the press, making it ideally suited to the feeding of shaped coin blanks, bi-metallic (non-homogenous) coin blanks and large diameter (homogenous) blanks, which can cause problems with existing blank feeder mechanisms, and particularly where frequent denomination change-overs are required. However, by the inclusion of the two blank feeding units 15 and 16 on a press driven by two respective electric motors 24, synchronised to the operation of the press through an encoder, the system can be configured so as to feed in sequence and at the same frequency as the operating speed of the press, or at half press speed when it is required to feed into alternate blank-receiving recesses of the feed plate 11.

The former would then allow the feeding of bi-metallic blanks, comprising a separate "outer" and a separate "inner", whereas the latter, (providing the feeder unit stations are place an "odd" number of indexes apart) allows feeding of the more difficult shaped or large diameter blanks.

It is the combination of a specially developed mechanism, and the ability to control the rotational speed of the or each motor within each cycle of the press, which affords the best conditions for the feeding of each particular blank. The further advantage offered by this flexible system is that any of these modes may be selected simply by an electrical switch.

Figure 3 of the drawings is a motion profile of the feeder mechanism, in relation to the operating cycle of the press.

The embodiment of the invention therefore provides blank feeder units for a coining press which utilises a specially developed slider crank mechanism driven by an electric motor, and having the following advantages, inter alia, over conventional means of driving them: 1. The feeder unit is driven by electrical motors, independent from any mechanical drive from the press.

2. The feeder unit comprises a specially developed slider crank mechanism arranged so as to provide a dwell in the motion profile to facilitate coin blank feeding for a constant speed input.

3. The operational speed of the feeder unit, provided by the electrical motor, can be further varied to tailor and optimise individual blank feed requirements provided the overall time for one complete cycle is the same as if the unit had a constant speed input.

4. The motor is synchronised to the press and dial feed plate via an electrical encoder.

5. Two feeder units, placed "odd" number of dial plate indexes apart can be tailored and optimised to feed bi-metallic coin blanks (both units operating at press speed), the first feeding the outer, the second feeding the inner, and also to feed the more difficult large diameter blanks and shaped blanks (both units operating at half press speed and hence feeding alternately) comfortably.

6. All operational modes and individual motion profiles for each blank denomination can be simply selected via an electrical switching system.

7. Decreased production downtime for denomination changeovers including automatic recall of previous defined optimisation parameters.

Claims

1. A coining press which comprises: an indexable feed plate having a plurality of circumferentially spaced blankreceiving recesses in its periphery; a coining tool arranged at a forming station adjacent to the periphery of the feed plate; and a blank feed unit arranged at a feeding station also adjacent to the periphery of the feed plate and circumferentially spaced from said forming station, said unit comprising a stacking device for receiving a stack of coinforming blanks, and a feeding device engageable successively with the instantaneously lowermost blank of the stack to feed the latter into an adjacent blank-receiving recess in the periphery of the feed plate, in which: an electrically operable driving device is coupled with said feeding device to operate the latter between a retracted position and an extended position in order to move the lowermost blank into a respective recess in the feed plate; and, a control arrangement is connected to said driving device and is arranged to monitor the operation of the press so as to operate the electrically operated driving device in synchronism with the operation of the press.

2. A coining press according to claim 1, in which the feeding device comprises a feed finger, arranged to be driven by a crank mechanism having a short coupling length, said mechanism being arranged to be driven by an electric motor whose initiation, and speed of operation is controlled by said control arrangement which monitors the operation of the press.

3. A coining press according to claim 2, in which the crank drive mechanism is configured so as to create, effectively, a dwell of the finger, and which allows an increased time for the next blank in the stack to drop into place, prior to being pushed into the next receiving recess in the periphery of the feed plate.

4. A coining press according to any one of claims 1 to 3, in which the control arrangement comprises an encoder arranged to be driven by the press.

5. A coining press according to claim 4, when appended to claim 3, in which the electric motor and the encoder are operative to enable the feed system to keep in step with the press at all operating speeds, but also to allow the rate of speed to be varied during each cycle so that the blank-feeding unit operates entirely in synchronism with the operation of the press.

6. A coining press according to any one of claims 1 to 5, in which two separate blank-feeding units are arranged at circumferential spacings relative to the periphery of the feed plates, so as to allow composite coins to be formed from more than one coin blank.

7. A coining press according to claim 6, in which each of said two blank feeding units is arranged to be driven by a respective electric motor synchronised to the operation of the press through an encoder, whereby the system can be configured so as to feed in sequence and at the same frequency as the press operating speed, or at half press speed to feed into alternate dial plate stations.