GB2063739A - A device for ejecting cores from castings - Google Patents

Abstract

A device for ejecting cores from castings (a) has a hammer (10) which is positioned in a pivotable holding part (11) and whose striker part (10') acts on the casting (a) while generating vibrations thus causing the core sand to be loosened. The device has a turntable (1) which can be rotated through respective equal indexing steps and is provided with a number of angularly equispaced holders (5) for receiving the castings (a). The pivotable holding part (11) holding the hammer (10) is capable of being moved towards the table (1) into its operative position and away from the table (1) into its inoperative position. Castings may be loaded automatically into the holders (5). <IMAGE>

Description

SPECIFICATION A device for ejecting cores from castings The present invention relates to a device for ejecting cores from castings with a hammer which is positioned in a holding part and whose striker part acts on the casting while generating vibrations, thus causing the core sand to be loosened.

One commonly used method of ejecting cores from castings, by means of a hand-held compressed-air hammer, requires much effort and is therefore expensive. Because of the noise and the dust produced and because of the vibrations it also reduces the performance of the person carrying it out, and it may even be injurious to health. A device described in German Patent Specification No. 517,781, against whose horizontal striker element arranged at the top of a stationary trestle the casting to be treated is held, provides relatively little easing of this operation. Bodily force is required to press the castings against the striker. The two main consequences are the exposure of the operator to hazardous vibrations and bodily stress, and these cannot be endured over prolonged periods.

Accordingly, an aim of the present invention is the creation of a device which is of the construction set out in the opening paragraph of the present Specification, and which enables cores to be ejected from castings mechanically in a rational manner.

The present invention is therefore directed to a core ejecting device in which a turntable carries the castings which can be rotated through respective equal indexing steps and is provided with a number of angularly equispaced holders for receiving the castings, and in which the said holding part is capable of being moved towards the table into its operative position and away from the table into its inoperative position.

Such a device allows the cores to be ejected from castings with much less bodily stressing of the operator and also much more rationally than when the previously proposed method of working is used. Cores can be ejected without leaving a residue and without causing damage to the casting even in the case of sharply curved thin-walled castings as are employed, for example, in the construction of engines.

Hitherto, these have had to have their cores ejected manually. In addition, there is much less risk of an accident to the person operating the device than with previously proposed core ejection processes. Moreover the operator is less exposed to vibrations or dust.

The table which carries the castings may have a polygonal plan view, for example a hexagonal shape, and may be constructed as an upwardly pointing truncated pyramid.

Advantageously, an enclosure for the entire device in the form of a sound-reducing booth which can be lifted off as necessary is provided. The entire inner walls of this booth are covered with sound-absorbing material and an opening for loading and unloading castings on to and from casting carriers on the table is provided only on a loading side of the table which is suitably provided to lie on the opposite side of the table to the hammer. The booth can be made to provide a very considerably silencing effect during the core ejection process, with the noise being kept to a level which can be endured without injury to health. In addition, the sound-absorbing booth creates the requisites for an almost compete absence of environmental pollution such as, for example, generation of dust.

An example of a device for ejecting cores from castings in accordance with the present invention is illustrated in the accompanying drawings, in which: Figure 1 shows a longitudinal, partly sectoned view of the device; Figure 2 shows a plan view of the device shown in Fig. 1, with lid parts of a sound absorbing booth housing the device removed to reveal parts of the device; Figure 3 shows an overall perspective diagrammatic view of the sound-absorbing booth; Figure 4 shows a partly sectional view of a holder of the device with a casting provided on a table; Figure 5 shows a sectional side elevational view of the parts shown in Fig. 4; and Figure 6 shows a section of the parts shown in Fig. 4 taken on line Vl-Vl thereof.

A turntable 1 shown in Figs. 1 and 2 carries the castings and is caused to rotate by a Geneva movement mechanism (not shown) driven by a motor 2 through equal indexing steps each of 60 . The table top 1' of the table 1 is hexagonal in plan view (as more clearly seen in Fig. 2) and has respective mounting plates 3 arranged around its sides.

From the table top 1' these mounting plates 3 extend downwardly and obliquely outwardly so that the table 1 forms a truncated pyramid pointing upwards in front elevation. In their central region, the mounting plates 3 are provided with a respective recess 3' and are supported by the table top 1' via reinforcing angle parts 3". Angularly equispaced holders 5 are positioned on each of the peripheral surfaces 1" of the table 1 formed by the outer surfaces of the mounting plates 3. Each holder accommodates a casting a displaying a plurality of cores to be broken. The holder 5 illustrated particularly in Figs. 4 to 6 consists of a receiver 6 made up of two parallel, spaced apart guide strips arranged on the peripheral surfaces 1" of the table 1 and of a casting carrier 7 adapted to the shape of the respective casting a and insertable in the receiver 6.A rubber cover 4 secured to the mounting plate 3 is arranged between the back of the carrier 7 and the facing outside surface of the mounting plate 3. An abutment stop 6' provided at the bottom of the receiver 6 defines the ultimate position of the carrier 7. The castings a may be alike and/or vary in construction and are held in the carrier 7 without clamps merely by the bearing arms 7' and the covering arm 7" around their external contours.

The table 1 rests on a plurality of columns 9 which, together with a holding part or receiver constructed as a pivoting device 11 and holding a hammer 10, are fastened to a base frame 1 2 consisting of sectional beams.

This frame rests on the floor of the manufacturing shop via a plurality of interposed impact-damping bearing elements 1 3. The pivoting device 11 consists of two parallel mutually spaced apart side parts 14 which are rigidly connected to one another by a bracket 1 5 carrying the hammer 10. At their bottom ends facing the table 1 the side parts 14 are hinged to two bearing blocks 1 7 fastened to the base frame 12 by trunnions 16. A housing of a pneumatically actuated lift cylinder 1 8 is fitted to the bottom half of one of the side parts 14.A rocking lever 1 9 is hinged to a free end-secton of the piston rod 18' of this lift cylinder 18, and this lever 1 9 is hinged to a pivotal attachment 20 offset from the base frame 1 2. In the operative position of the hammer 10, the piston rod 18' and the rocking lever 1 9 make an angle of about 100" to 130 with one another. Longitudinal movements of the piston rod 18' in the direction of the arrow b cause the pivoting device 11 to be swung into its operative position towards the table 1 about the trunnions 1 6. It is pivoted away from the table into its inoperative position in the direction c' of the arrow (direction b' of the arrow of the piston 18').A vertically adjustable abutment stop 21 is provided on the base frame 1 2. It is arranged in such a way that a setscrew 21' of the stop 21 co-operates with a rear end-portion of the lower edge of one side part 14 in the inoperative position of the pivoting device 11. The hammer 10 is fastened to the bracket 1 5 in such a way as to allow the pivoting device 11 to be swung in the plane of the axis of rotation of the table 1. In the operative position of the device 11 the longitudinal axis of the striker 10' of the hammer 10 extends approximately at right angles to the axis of rotation of the table 1.

A roughly rectangular abutment 22 is positioned opposite the hammer 10. At one end it is hinged so that it can rotate there but cannot undergo translational movement, while the piston rod 23' of a pneumatically actuated lift cylinder 23, itself hinged to the base frame 12, is hinged to the lower middle portion of the abutment 22. When this piston rod 23' moves longitudinally in the direction of the double arrow d, the abutment 22 can be pivoted from its inoperative position shown by continuous lines into its operative position shown by dot-dash lines. In this operative position it is urged against the back of the casting carrier 7.

An actuating mechanism 25 which faces the back of the carrier 7 is provided at the loading point e of the table 1 at the table foot formed by the columns 9. This actuating mechanism 25 imparts the required impact time to the striker 10' of the hammer 10 acting on the casting a. To this end the mechanism 25 is provided with a time switch and is connected to the hammer 10 by an appropriate circuit. It is also provided with six actuating keys 26 equalling the number of holders 5 provided around the periphery 1" of the table 1. The superposed keys 26 cooperate with cams 27 located on the back of each casting carrier 7. These cams are arranged on the carriers 7 at varying heights as a function of the respective impact times which the hammer 10 is to operate for. These varying heights are shown in Fig. 4 by means of dot-dash lines.The position of the cams 27 relative to the individual keys 26 is selected to correspond to the impact time to be selected for the respective casting a. It is a function mainly of the number, size and composition of the cores which need to be ejected. After introduction of the carrier 7 into the receiver 6, the selected cam actuates the key 26 which imparts the set impact time for the respective casting a to the hammer 10. The uppermost key 26 can serve to impart the shortest impact time, for example, while the lowest key imparts the longest impact time.

Furthermore, a limit switch 29, having its elastically mounted sensing finger 30 located on the free end of a U-shaped holder 31, is positioned within range of the hammer 10.

With its vertical arm the holder is rigidly fixed to one of the columns 9 of the table 1. The sensing finger 30 is arranged above the casting a in the carrier 7 in such a way that it makes contact with the casting. The limit switch 29 communicates with both the pivoting device 11 and the abutment 22 via a pneumatic circuit. This circuit is constructed in such a way that, when the sensing finger 30 of the limit switch 29 makes contact with the casting a inserted in the carrier 7 and lying opposite the hammer, the piston rods 18' and 23' of the pneumatic lift cylinders 18 and 23 are extended outwards. At the same time the pivoting device 11 and the abutment 22 are pivoted into their operative position.

On the other hand, if there is no casting a in the carrier 7, then the limit switch 29 does not respond and the pivoting device 11 and the abutment 22 are swung into their inoperative position. This movement is brought about by an appropriate switching of the pneumatic circuit which, for this purpose, may be linked to the time switch of the switching mecha nism 25. Moving of the pivoting device 11 and of the abutment 22 over the relatively large distance is effected by virtue of the difference between the circumscribing and inner circle diameters of the hexagonal table 1.

To ensure that the carriers 7 are loaded with the "correct" casting a during core ejection of possibly varying castings a arranged in adjacent carriers 7 in the simplest possible manner, a pattern part a' which is smaller than the casting a to be processed may be provided on the table 1 within range of the casting a. Further, sound-absorbing devices 24 may be positioned on the table 1 in order to reduce noise. Figs. 1 and 2 show further that the entire device according to the invention is enclosed by a booth 33 shown in perspective in Fig. 3 which has a silencing effect and can be lifted off as necessary. This silencing booth 33 consists of a part 34 covering the table 1 and a part 35 covering the pivoting device 11. The two parts 34 and 35 are detachably connected by a locking mechanism and consist of wall parts 36,36',36" and of roof parts 37,37".The wall parts 36,36' and the roof part 37 of the part 34 of the booth are fixed detachably to a tubular scaffolding 38 which encloses the table 1 on all sides at some distance from it.

In contrast, the wall parts 36" and the roof part 37" of the part 35 of the booth enclosing the pivoting device 11, also at some distance from this same, are connected in undetachable manner. This construction of the booth 33 allows the wall parts 36,36' and the roof part 37 of the part 34 of the booth to be removed. Alternatively, the part 35 of the booth can be taken off in its entirety during essential maintenance and repair work on the drive, thus allowing ready access to the device from all sides. All the wall parts 36,36',36" and the roof parts 37,37" are provided with sound-absorbing material which is suitably positioned between two perforated metal sheets, thus providing wall parts which resist bending in addition to reducing noise. A release cord 39 extends alongside the facing wall parts 36 of the booth part 34.This cord is connected to each wall part 36 in such a way that when a part 36 is removed from the tubular scaffolding 38 an emergency switch is actuated which brings the table 1, if rotating, to a halt.

The wall part 36' of the booth part 34 has an opening 40 on the loading side e of the table 1 serving for loading and unloading the carriers 7 with castings a. The maximum width of the opening 40 is approximately 700mm so that not more than one operator at a time can obtain access to the holder 5 of the table 1. A respective, if desired lockable actuating key 41 for starting up the table 1 is positioned within range of two side-walls of the opening 40 and is thus within its manual reach. For reasons of safety this actuating key needs to be operated with two hands, i.e. jointly. In addition, the opening 40 may be provided with a safety device, a lockable protective grid, a light barrier or a like device which allows the operator access to the holders 5 only when the table 1 is at rest.

Finally, a pilot light 42 which lights up to signal the end of the core ejection process of the casting a is provided within view of the opening 40, thus enabling the operator to insert a further casting to be treated in the carrier 7. Within range of the opening 43 for the hammer, the booth part 34 is provided with two actuating keys 44 constructed to be operated with two hands. When a test run of the table 1 is necessary, they serve to cause the current circuit to be bridged when the part 35 of the booth covering the pivoting device 11 needs to be removed.

The mode of action of the illustrated device is as follows. When the pivoting device 11 and abutment 22 are in their inoperative position, the pilot lamp 42 lights up and informs the operator at the loading point e of the table 1 that a casting a can be inserted in the carrier 7 of the holder 5 ready to have its cores ejected. Since a pattern part a' corresponding to the casting a is positioned on the table 1, insertion of the wrong casting a is normally avoided. The carrier 7 intended to accommodate the casting a, and equipped with the bearing arms 7' and the covering arm 7" in order to secure the external contours of the casting a, is next inserted in the receiver 6 of a holder 5.In the end-position of the carrier 7 the cam 27 actuates that key 26 which is to issue the impact time of the striker 10' of the hammer 10 required for ejecting the core from the inserted casting, for example 1 minute. The impact time remains stored until the inserted casting a is positioned opposite the hammer 10 ready for treatment. If, following ejection of the cores from the casting a, respectively alike castings are successively inserted in the carrier 7, then, naturally, the carrier can remain in the receiver 6 and it is necessary merely to insert the casting a.

Also, after a complete rotation of the table 1 through 360 the cam re-actuates the associated key 26. Changing the carrier 7 is thus necessary only if castings a of varying construction are involved.

Next, the operator uses both hands to operate the two keys 41, thus causing the carrying table 1 to be turned further by the Geneva movement mechanism through an indexing step of 60o, for instance in the sense of the arrow t: The carrier 7, and all following carriers 7 which appear at the loading point e of the table 1, can be provided with a respective casting a. After a total of three indexing steps the initially inserted casting a comes to-lie opposite the hammer 10 and it then makes contact with the sensing finger 30 of the limit switch 29. In the aforementioned manner the pivoting device 11, on the one hand, and the abutment 22, on the other hand, are then pivoted into their operative position by a pneumatic circuit, while at the same time the pilot light 42 goes out.The abutment 22 is urged against the back of the carrier 7, thus providing counter-pressure against the impact forces from the striker 10' of the hammer 10.

When the pivoting device 11 is in its inoperative position, then the striker 10' of the hammer 10 actuated by a switching pulse and driven by compressed air acts on the impact point h of the casting a by striking approximately 1 200 blows per minute. Since the casting a rests on the bearing arms 7' and the covering arm 7" of the carrier 7 merely with its own weight, i.e. is not clamped to these, very strong vibrations are generated due to the impact by the striker 10' on the casting a.

These vibrations cause the sand forming the cores present in the casting a to be loosened from the casting and to fall downwardly through the grate 45 of the core ejection installation. The impact point h on the casting a supported by the covering arm 7" is fixed structurally, that is to say it is at a predetermined point which is positioned as favourably as possible on the casting a, suitably on the gate. After the impact time issued to the hammer 10 by the actuating device 25, for example 1 minute, has elapsed, the pivoting device 11 and the abutment 22 are pivoted into their inoperative position. At the same time the pilot lamp 42 lights up to tell the operator at the loading point e that the table 1 can be turned further through one indexing step.After three further indexing steps, each involving the same coreejection operation already described, the corefree casting a appears at the loading point e of the table ready to be unloaded. Subsequently, a further casting a can be inserted in the now vacant carrier 7.

If there is no casting in one or more of the carriers 7, then, when an empty carrier 7 comes within range of the hammer 10, the sensing finger 30 of the limit switch remains in its inoperative position and the abutment 22 and also the pivoting device 11 remain in their inoperative position, while the pilot lamp 42 remains lit. The operator can then turn the table 1 further through one or more indexing steps without delay.

The hammer 10 may be constructed in such a way that the number of blows the striker 10' executes can be varied. It is also feasible to provide an automatic handling device for loading and unloading the castings a, so that the entire core ejection process is mechanised and substantially automated. Further, the device according to the invention allows sand to be removed from those castings to which external mould sand adheres.

Finally, a contact-free actuation of the actuating keys 26 is possible.

Claims (18)

1. A device for ejecting cores from castings with a hammer which is positioned in a holding part and whose striker part acts on the casting while generating vibrations, thus causing the core sand to be loosened, in which a turntable carries the castings which can be rotated through respective equal indexing steps and is provided with a number of angularly equispaced holders for receiving the castings, and in which the said holding part is capable of being moved towards the table into its operative position and away from the table into its inoperative position.

2. A device according to claim 1, in which the table is polygonal in plan view, for example hexagonal, and is constructed as an upwardly pointing truncated pyramid.

3. A device according to claim 1 or claim 2, in which the holders for the castings are respectively arranged on peripheral surfaces of the table and each comprise a receiver and a carrier for a casting which can be inserted in the receiver and is adapted to the shape of a casting, a rubber cover being provided between the back of the carrier and the facing peripheral surface of the table.

4. A device according to any preceding claim, in which the holding part holding the hammer is constructed as a pivoting device which is fastened to a base frame together with the table, with the base frame in its turn resting on the floor of the manufacturing shop or the like via interposed impact-cushioning bearing elements.

5. A device according to claim 4, in which the pivoting device has two parallel mutually spaced apart and rigidly connected sides whose lower end-regions facing the table are hinged to brackets themselves fastened to the base frame, the pivoting movements of the pivoting device being generated by at least one lift cylinder.

6. A device according to claim 5, in which the base frame is provided with at least one vertically-adjustable abutment stop for the pivoting device, which abutment stop is so arranged that its setscrew co-operates with the rear end-region of one of the sides.

7. A device according to claim 5 or claim 6, in which the hammer is fastened to a bracket connecting the two sides of the pivoting device in such a way that it is pivotable during pivoting of the pivoting device in the plane of the axis of rotation of the table, with, the longitudinal axis of the striker extending approximately at right angles to the axis of rotation of the table in the operative position of the hammer.

8. A device according to any one of claims 4 to 7, in which an abutment which is fixedly hinged at one end-region is positioned underneath the table opposite the hammer and by means of a lift cylinder can be pivoted from an inoperative into an operative position in which it is urged against the back of the casting carrier.

9. A device according to claim 3, or any one of claims 4 to 8 appended to claim 3, in which the impact time for the striker of the hammer is imparted to the hammer by an actuating device arranged on the foot of the table at a loading point thereof and facing the back of the carrier and which displays a plurality of keys co-operating with a cam located on the back of each carrier at varying heights to correspond to the respectively set impact time.

10. A device according to any preceding claim, in which a limit switch having an elastically-mounted sensing finger positioned on the free end of a stationary holder is provided adjacent to the hammer position.

11. A device according to any preceding claim, in which the entire device is enclosed by a sound-damping booth which can be lifted off when necessary and has its entire interior walls covered by sound-absorbing material and which displays an opening for loading and unloading castings onto and from the holders only on a table loading side provided to lie opposite the hammer.

1 2. A device according to claim 11, in which the sound-damping booth is made up of a part covering the table and a part covering the hammer holding part connected by a locking mechanism, the part covering the table having individual wall parts and roof parts which are detachably fastened to a tubular scaffolding enclosing the table on all sides at some distance, and in that the sound-absorbing material of the individual wall and roof parts is positioned between two perforated metal sheets.

1 3. A device according to claim 12, in which a release cord extends along the opposite wall parts of the part of the booth covering the table and is connected to each part of the wall in such a way that if a wall part is removed an emergency switch is actuated which brings the table, if rotating, to a halt.

14. A device according to any one of claims 11 to 13, in which two separate actuating keys for operating the table, which require to be actuated jointly, are provided within range of the opening of the sounddamping booth.

1 5. A device according to any one of claims 11 to 14, in which the opening of the sound-damping booth may be made safe by means of a safety device.

1 6. A device according to any one of claims 11 to 15, in which a pilot lamp which signals the completion of the ejection of a core from a casting, is positioned within view of the opening of the sound-damping booth.

1 7. A device according to claim 12, or any one of claims 1 3 to 1 6 appended to claim 1 2, in which the wall parts and the roof parts of the part of the booth covering the hammer holding part are non-detachably connected to one another.

18. A device according to claim 12, or any one of claims 1 3 to 1 7 appended to claim 12, in which two keys which, during a necessary test run of the table, serve to bridge the current circuit when the part of the booth covering the hammer holding part is removed are provided within range of the hammer opening of the part of the booth covering the table.

1 9. A device for ejecting cores from castings, substantially as described herein with reference to the accompanying drawings.