GB2067938A - A casting-core knockout machine - Google Patents

Abstract

The removal of a disintegrable core from a casting is achieved by vibration, assisted by an air or water blast. The casting is clamped between an anvil and the head of a percussion hammer (18) mounted on a vertically movable carriage (13). The latter is moved into engagement by a first ram (14) and firmly clamped by further rams (22, 23) so that even when vibrated the casting is not released. During vibration the fluid blast, augmented by particulate material, is applied to at least one aperture exposing part of the core. The core material may be recovered and used with the fluid blast to cleanse the casting. <IMAGE>

Description

SPECIFICATION A knockout machine This invention concerns a knockout machine which is used to remove disintegrable moulding media from cores of castings.

Precision castings, die castings, gravity die castings and sand castings of hollow metal bodies involve the use of cores that subsequently have to be removed. Such cores are generally made of sand or ceramic which is compacted and bonded to the internal shape of the casting. After casting its subsequent removal is a problem. In its initial post-casting state it is virtually impossible to do this by manual prodding or vibration, and generally the casting is placed in an oven for several hours, after which time the core is more amenable to removal. Often it is then vibrated by a hand-held tool, which loosens the sand sufficiently for it to be shaken out. This is an expensive and time consuming process, and the aim of this invention is to achieve a much more rapid and certain removal of such cores.

According to one aspect of the present invention there is provided a knockout machine for the treatment of castings with disintegrable cores, comprising a base for locating a casting, a percussion hammer, the base and hammer being relatively movable for the hammer head to clamp the casting against said base, and means for actuating said hammer to impart shock waves to the casting, the return stroke of the hammer being insufficient to release the clamping action.

According to another aspect of the present invention there is provided a method of knocking out disintegrable cores from castings, comprising clamping the casting between the head of a percussion hammer and an anvil and actuating the hammer to impart shock waves to the casting, the return stroke of the hammer being insufficient to release the clamping action.

In addition to the shock waves, the removal of the core may be further assisted by the application of a blast of air or water into one or more apertures of the casting at which the core is exposed. The interior of the casting may be cleaned by adding sand or other particulate abrasive to the air or water stream; and this may be provided by sand recovered from previously removed cores.

For a better understanding of the invention one constructional form will now be described, by way of example, with reference to the accompanying drawing in which: Figure 1 is a diagrammatic perspective cutaway view of a knockout machine, and Figures 2A and 2B illustrate air blast attachments.

The machine of Figure 1 is housed in a cabinet which has a massive frame 1 fabricated from steel box sections. There is a main door 2 giving access to the working area, which is visible through a double-glazed window 2A, and a lower door 3 for access to a chamber where the waste is received or disposed of. The walls, floor, ceiling and doors are all constructed from sound-proofing material.

Supported within and by the main frame 1 is a rectangular sub-frame 4, its plane being generally vertical and parallel to the closed door 2, and the projecting ends of its cross members bearing on anti-vibration mounts 5. Lower cross member 6 has a plinth 7 secured centrally on its upper surface with a locating aperture 8. Various anvils (not shown) can be mounted on this plinth, each having a stud to fit the aperture 8 and being selected according to the workpiece.

Brackets 9 project inwardly from the vertical side members of the sub-frame 4 and support the lower ends of hardened steel shafts 10 whose upper ends are threaded and secured by nuts 11 above the upper cross member 12. These vertical shafts 10 provide a guide for a carriage 1 3 which can be raised and lowered by means of a pneumatic or hydraulic ram 14. The carriage consists of upper and lower horizontal plates 1 5 and 16, each provided with linear bearings which slide on the shafts 10.The plates are held at a fixed distance apart by vertical rods 1 7. An air or hydraulically operated percussion hammer 1 8 is supported from the upper plate 1 5 by bolts 19, and its lower neck portion is held secure by the clamping action of a removable portion 20 in the lower plate 1 6. The hammer is aligned vertically with the centre of the plinth 7. The ram 14 acts between the underside of a plate 21, held horizontally beneath the cross member 12 and vertically movable on guide shafts 10, and the rear of the carriage 13.

It is important for the technique to be described for the hammer head to be held very securely against the workpiece. It is therefore not sufficient merely to raise and lower the carriage pneumatically into co-operation with the workpiece. To provide a locking/clamping or release action a further double action pneumatic or hydraulic ram 22 is mounted on top of the cross member 12, and having its piston rod connected to the plate 21 and aligned with the axis of the hammer 1 8. When the carriage has been lowered to an approximate working position, during which motion the ram 22 is kept retracted, the hammer head is clamped against the workpiece by operating the ram 22 to force the plate 21 downwards.The carriage 13 itself, and hence the hammer 18, is locked to the plate 21 by means of solenoid-controlled double acting hydraulic rams 23 symmetrically disposed on opposite sides of the hammer axis, these rams acting between the underside of the plate 21 and the lower plate 1 6 of the carriage 13. While the carriage is being lowered these rams freely extend, the solenoids being energised to open valves in the hydraulic circuit. However, when that movement is arrested, the solenoids are de-energised, the valves close, and a hydraulic lock is imposed. This is released again when the carriage is raised.

Although the hydraulic rams 23 could be large enough to make the pneumatic ram 14 redundant, the system shown is preferred in practice. A balanced locking arrangement on either side of the hammer is necessary and therefore at least two hydraulic rams are required. Large ones are very expensive and so it is considered best to provide two small ones sufficient to exert the lock, and to generate the coarse primary movement by means of a relatively large and cheap pneumatic ram.

The various pneumatic and hydraulic controls will not be described in detail as they will be apparent from the description of operation below, but the machine has a very simple control panel 24 with buttons and levers which function as indicated. There is also an air or hydraulic pressure regulator 25 for varying the hammer percussion rate.

For operation, a suitable anvil is mounted on the plinth 7, and the workpiece is placed upon it.

Generally there will be a runner or ingate projecting from the main body of the casting which forms the workpiece, and usually it will be this runner that is placed on the anvil to be engaged by the hammer. When in a roughly suitable position, the carriage is lowered until the hammer head engages the workpiece. When that lowering movement ceases, the carriage will be locked hydraulically to the plate 21 as described.

However, the workpiece is still only under gravity pressure of the hammer head and can still be adjusted by the operator. When the casting is finally located in its correct position ram 22 is energised and the workpiece is then securely clamped under very considerable pressure. This pressure can be varied within limits to suit the workpiece. It will be such that when the hammer 18 is actuated even on the return stroke there will be no chance of the workpiece being released. The door 2 is then closed and the hammer is actuated, and this will impart shock waves throughout the workpiece, rapidly releasing the compacted sand core. The core material will be shaken out into the lower chamber of the cabinet.

In conjunction with this machine there may further be provided means for more rapidly removing the sand core by an air or water blast applied during the vibration. Two examples are shown in Figures 2A and 2B, in both of which the clamped casting C is illustrated as a T-shaped member with a correspondingly shaped core exposed at the ends of the arms and stem.

In Figure 2A the delivery end 26 of a high pressure air or water hose 27 is attached to the end of a pivoted arm 28 actuab!e by a pneumatic ram 29. The arm and ram will both be mounted on the sub-frame 4, preferably with some adjustment facility to cater for different castings. The end 26 has a flange 30 faced with a rubber seal 31 to engage the end of one arm of the casting C, as indicated by the broken line position.

In Figure 2B the hose is shown at 32 and it terminates in an elbow 33 with a flange 34 and seal 35. A pneumatic ram 36 is aligned with the delivery portion of the elbow and is coupled to a lug 37 projecting rearwardly from it. In this embodiment the delivery end makes a rectilinear approach to the casting, and the coupling to the ram 36 can allow for modest variations in casting angle. The position of the ram will again be adjustable for different castings.

In each case, the casting C is left with the core exposed at two points, and when the vibrations are imparted the air or water blast hastens the ejection of the broken down core material from these casting apertures.

It will be understood that only simple embodiments have been shown, and that more complex castings may require correspondingly more complex treatment and apparatus. For example, with many casting apertures the fluid blast might be applied to more than one, of course always leaving at least one exposed for the escape of core material and the fluid. There may be separate hoses for each aperture, or a single one fitted with a manifold. Alternatively, there could be a programmed sequence of blasting all apertures, either with a hose being moved from aperture to aperture or with a plurality of hoses operating in turn, those not operating being withdrawn from their apertures or being adapted to receive and duct away the sand and air/water issuing from the casting.

The blast can be further used to produce a thorough cleaning effect. Special blasting sand or other abrasive can be added to the air or water, but preferably the sand already dislodged from previous castings is re-used after collection and a suitable grading process.

Claims (17)

1. A knockout machine for the treatment of castings with disintegrable cores, comprising a base for locating the casting, a percussion hammer, means for relatively moving the base and hammer for the hammer head to clamp the casting against said base, and means for actuating said hammer to impart shock waves to the casting, the return stroke of the hammer being insufficient to release the clamping action.

2. A machine as claimed in Claim 1, wherein a vertically movable carriage provides a mounting for the hammer, with fluid operated rams for controiling the movement.

3. A machine as claimed in Claim 2, wherein a first ram governs a primary movement of bringing the hammer into engagement with a workpiece and a second ram exerts the clamping action.

4. A machine as claimed in Claim 3, wherein the second ram acts between a fixed and a vertically movable member and the first ram acts between the vertically movable member and the carriage, there being means for locking the vertically movable member and carriage at a spacing determined by the first ram.

5. A machine as claimed in Claim 4, wherein the locking means includes a hydraulic ram acting between said vertically movable member and the carriage and valve means which when closed isolate the fluid in the hydraulic ram, thereby locking it.

6. A machine as claimed in Claim 5, wherein means are provided for opening the valve means when the first ram is in operation and closing the valve means when it is not in operation.

7. A machine as claimed in any preceding claim, wherein the base has means for receiving any of a selection of anvils against which the castings are clamped.

8. A machine as claimed in any preceding claim, enclosed in a housing from which the core material can be recovered.

9. A machine as claimed in any preceding claim, and including fluid blasting means for cooperation with castings to deliver high pressure fluid at at least one aperture at which the core is exposed.

10. A method of knocking out disintegrable cores from castings, comprising clamping the casting between the head of a percussion hammer and an anvil and actuating the hammer to impart shock waves to the casting, the return stroke of the hammer being insufficient to release the clamping action.

1 A method as claimed in Claim 10, wherein a blast of fluid is applied to at least one aperture at which the core is exposed.

12. A method as claimed in Claim 11, wherein the fluid is augmented by a particulate abrasive.

13. A method as claimed in Claim 12, wherein the core material from previous castings is recovered and used to provide, at least in part, said particulate abrasive.

14. A method as claimed in Claim 11, 12 or 13, wherein the blast is applied to various apertures in turn.

1 5. A method as claimed in Claim 14, wherein blast delivery means is moved from aperture to aperture.

16. A method as claimed in Claim 14, wherein a plurality of blast delivery means are provided, each for co-operation with an associate aperture, those not issuing the blast being withdrawn from their apertures.

17. A method as claimed in Claim 14, wherein blast delivery means are applied to a plurality of apertures and those not issuing the blast are used to duct away material from the casting.

1 8. A knockout machine substantially as hereinbefore described with reference to Figure 1, with or without Figure 2A or 2B of the accompanying drawings.

1 9. A method of knocking out disintegrable cores from castings substantially as hereinbefore described with reference to Figure 1, with or without Figure 2A or 2B of the accompanying drawings.