EP0008427A1

EP0008427A1 - Device for manufacturing a casting form

Info

Publication number: EP0008427A1
Application number: EP79102912A
Authority: EP
Inventors: Johan Hubert Antoinette Caluwe; Charles Defrancq
Original assignee: De Pecker NV
Current assignee: De Pecker NV
Priority date: 1978-08-22
Filing date: 1979-08-10
Publication date: 1980-03-05
Also published as: NL7810887A

Abstract

The means for feeding form material between the model (19) and the die parts (3,4) comprise a metering mechanism (21, 22, 23, 24) to determine a form material dosis, feeding means (25) to feed form material to the metering mechanism (21, 22, 23, 24), and a vibrating mechanism (13) which can cause at least one of the parts formed by the support (7), the die parts (3,4) and the model (19) to vibrate. Means to retain the die parts (3, 4) together are formed by at least one spring (9) which is mounted under strain on that unit formed by the support (7) and the die parts (3, 4) mounted thereon, and which always tries to move said die parts (3,4) towards one another.

Description

This invention pertains to a device for the manufacturing of a casting form, which comprises a support, at least two die parts at least one of which is so mounted as to be movable relative to said support, a model of the part to be molded arranged between said parts, means to feed form material between the model and the die parts, and means to retain the die parts temporarily together.
In known devices of this kind, the means to feed form material in the space between the model and the die parts is formed by a movable injection device with which form material which is generally sand to which additives are added, is injected under pressure in said space. The pressurized injecting of the form material requires however relatively much energy. Moreover the wear of the model and die parts by the scouring action of the pressure-injected form material is relatively high. The die parts and the model also have to be fitted specially for the injection which makes the manufacture thereof more intricate. Particular arrangements are always necessary to let air escape from the form. The compression rate and homogeneity of the fed form material are dependent on the injection pressure and are not always as desired.
The invention has for object to obviate the above drawbacks and to provide a device for the casting of metal whereby with a minimized energy supply and minimized wear of the die parts and model, and without requiring an intricate structure of the die parts and the model, a very homogeneous filling with form material can be obtained between the model and the die parts, with the desired compression rate.
For this purpose the means for feeding form material between the model and the die parts comprise a metering mechanism to determine a form material dosis, feeding means to feed form material to the metering mechanism, and a vibrating mechanism which can cause at least one of the parts formed by the support, the die parts and the model to vibrate.
The complete space between the model and the cooperating die parts is filled with a form material dosis which falls inside said space under the influence of gravity. Due to the vibrating by means of the vibrating mechanism, said space is filled uniformly. Of course said dosis is suited to the size of said space.
In a particular embodiment of the invention, the metering mechanism comprises a tank provided with an outlet, a closure device on said outlet, disconnectable means to feed form material to the tank, means to control said latter-mentioned means to disconnect the feeding to said tank when the desired amount of form material has been fed to said tank, in such a way that the feeding to the tank stops, and means to open said closure device.
The invention also relates to the means provided to retain the die parts together.
In the known devices for the manufacture of a casting form, the form is closed either by rigid hooks or by piston mechanisms. It is clear that the use of said hooks is not completely suitable. The die parts always have to be retained together during the feeding of the form material and during the casting, but they should temporarily be moved away from one another to allow arranging the model in position, after hardening of the form material removing said model, and finally also removing the cast part. Moreover the use of hooks also causes problems when casting a casting material which expands during the solidifying, as it is the case with grey iron.
With such expanding both die parts always have to move somewhat away from one another. This has been solved by arranging between the hooks and the die parts, small lead pieces which can be distorted. The distorting of said small pieces is however not resilient in nature but rather plastic, in such a way that new lead pieces have to be used every time. All of the above-defined drawbacks are actually obviated when using piston mechanisms, either pneumatic or hydraulic ones. With the known devices for casting metal with such piston mechanism, said mechanisms are permanently mounted on the support on which said die parts are also mounted. These piston mechanisms are of double-action type and control either the closing and retaining together of the die parts, or the opening and retaining open of the die parts. Said piston mechanisms actually allow some expanding of the casting form. The large drawback of said mechanisms is however that during the complete casting operation, in other words in every location where the casting form may lie, the piston mechanisms are working and there should consequently be provided an energy source for the required pressure of the fluid for operating said piston mechanisms. Indeed during the major portion of the time required for the complete casting operation, and notably during the shaping of the form material, the casting and the cooling of the cast material, the die parts have to be pressed together.
The invention has for object to obviate said drawbacks and to provide a device for the manufacturing of a casting form whereby the means to retain the die parts together can be opened automatically very easily and allow the somewhat moving away of the die parts when the cast casting material expands during the solidifying, but with said means still being very simple to manufacture and to operate.
For this purpose said means to retain the die parts together are formed by at least one spring which is mounted under strain on that unit formed by the support and the die parts mounted thereon, and which always tries to move said die parts towards one another, while the device comprises means to compensate the action of the spring and to move apart and retain spaced temporarily said die parts.
By "spring" is meant here any resiliently- distortable component, particularly metal coil springs and plate springs, which can exert continuously and due to their very nature, a force on at least one of said die parts, as opposed to piston mechanisms which exert a force only when the fluid is kept pressurized. By means of the spring the die parts are thus retained together without continuously feeding energy thereto. When the die parts are to be moved away, some energy is then required but this is also the case with piston mechanisms.
In a particular embodiment of the invention, the spring is fixedly mounted between a rim integral with said support and the one die part, while at least one other die part is made fast to the support.
In another embodiment of the invention, the means to retain the die parts together comprise a mechanism which insures a smooth engagement of said die parts.
In a preferred embodiment the support is movable along a determined path, while the means to move said die parts away from one another are arranged along said path.
Other details and features of the invention .will stand out from the following description, given by way of non limitative example and with reference to the accompanying drawings, in which :

Figure 1 is a side view of a device for the manufacturing of a casting form according to the invention.
Figure 2 is a top view of the device shown in figure 1.

In both figures the same reference numerals pertain to similar elements.
The device for the manufacturing of a casting form as shown in the figures comprises a carriage 1 which runs on rails 2. Said rails 2 form a closed circle. The carriage 1 is moved either continuously or intermittently in a known way not described in detail here, whereby the succeeding operations such as the forming of the casting form, the casting and the solidifying occur in succeeding locations.
The casting form to be manufactured is of that type comprised of the combination of a die and a sand form. The device then further comprises two metal die pari; 3 and 4 between which is formed a hollow space 5 which is but partly filled with form material at this time. The one die part 3 is removably fastened to an upright wall 6 which is positively secured to a horizontal support 7 which is mounted on carriage 1.
The other die part 4 is also removably fastened to an upright wall 8 which is however movable relative to said wall 6, by means of projections which slide inside grooves which are provided in support 7. Said die parts 3 and 4 thus can be moved together and away from one another. To cast parts having another shape, the die parts 3 and 4 can be replaced when required.
Both die parts 3 and 4 are continuously pushed towards one another under the action of a heavy metal spiral compression spring 9 which is arranged between upstanding wall 8 and a facing upstanding wall 10, said spring being stressed, that is partly compressed. Upright wall 10 is positively secured to horizontal support 7. Said spring 9 insures without any energy supply, that the form be retained closed, that is thus that die parts 3 and 4 are retained together. A force is required to move said parts away from one another.
To prevent that after the discontinuance of that force retaining said die parts away from one another against the action of spring 9, said die parts 3 and 4 move very rapidly together with an impact, damper means 11 of known structure is arranged between walls 8 and 10. Said damper means 11 does not prevent the moving away from one another of die parts 3 and 4 but insures that said parts move but slowly towards one another and consequently engage one another slowly.
The support 7 is mounted by means of springs 12 on carriage 1. On said carriage 1 is mounted a vibrating mechanism 13 of known structure, which can vibrate support 7 and consequently the complete easting form relative to carriage 1. It is of course also possible to arrange the vibrating mechanism 13 instead of on carriage 1, along the path of said carriage, said vibrating mechanism then engaging temporarily the casting form to vibrate same.
The opening of the casting form, that is thus the moving away of die parts 3 and 4 can occur with known devices. A suitable apparatus 14 is shown diagrammatically in figure 2. Said apparatus comprises two arms 15 which can be pushed away from one another by means of a piston mechanism 16 and which are movable relative to carriage 1 by means of a piston mechanism 18 which is so controlled that at the right time, when a carriage 1 lies facing said arms, the arms can grip two projections 17 which are provided respectively on walls 6 and 8. Said arms can then push wall 8 away from wall 6, wereby thus the spring 9 will be compressed. With a continuous movement of the carriages 1, said apparatus 14 will move along with carriage 1 as long as said die parts 3 and 4 have to be retained spaced. When this is no longer necessary, the arms move away from the casting form so that they are relased from said projections 17 and as described above, die parts 3 and 4 are moved back together under the action of spring 9. The arms of apparatus 14 are returned to the original position thereof either by springs, or by piston mechanism 16 which has moved same away from one another, said mechanism then being a double-action one.
The cycle followed by a carriage 1 during the complete casting operation, starts at one of the opening apparatus 14. While said apparatus 14 retains said die parts 3 and 4 spaced away, a model 19 of the part to be cast is arranged inside space 5. Said model 19 is mounted in a known way on a plate 20 which is retained relative to support 7 between die parts 3 and 4. In the completely closed condition of the casting form, that is the position as shown in the figures, die parts 3 and 4 close against plate 20.
Directly after fastening the model 19, the die parts 3 and 4 are left to return together. That portion still free inside space 5, that is the volume between model 19 and the connecting die parts 3 and 4, is filled with form material. To the contrary of the known methods whereby the form material is pressure-injected in said space, the form material is left to fall under the action of gravity in said space. The device for the manufacturing of a casting form comprises therefor also a metering device and a device for feeding form material thereto, while the vibrating mechanism 13 insures that said form material is homogenously distributed inside said space and does not include any air inclusions. The metering device is formed by a tank 21 which is provided at the bottom with an outlet 22 wherein is mounted a closure or valve 23. Said tank 21 is mounted on a weighing device 24 which is mounted in a fixed position alongside the path of carriage 1, on a frame not shown in the drawings. The tank 21 is open at the top. The form material is supplied to said tank by an endless belt 25 which is mounted relative to said frame and is driven by a motor not shown in the figures. Said form material falls, for instance through a funnel, on the upper surface of endless belt 25. Said belt 25 is so arranged that it lies with a lengthwise edge above the open top side of tank 21. Level with tank 21 is arranged a scraper 26 which is slantingly directed relative to the lengthwise direction of the top side of endless belt 25. Said scraper 26 is movable up-and-down by means of a piston mechanism 27 which is mounted on said frame. In the lowermost position thereof, the scraper 26 contacts the top side of endless belt 25 so that the form material which is present on said belt top side is directed therefrom to the tank 21. The movement direction of said endless belt 25 is shown by arrow 28 in figures 1 and 2. The piston mechanism 27 is controlled by the weighing device 24. Said weighing device is so adjusted that when a determined weight of form material is present inside tank 21, said device couples a signal to piston mechanism 27 whereby said mechanism 27 raises scraper 26 and thus no more form material is fed to tank 21. When carriage 1 has reached the suitable position, a signal is coupled to valve 23 whereby same opens and thus an accurately metered amount of form material falls into space 5 which lies precisely underneath outlet 22. It is clear that said space 5 should be open completely or at least partly on the top side.
During the hardening of the form material, the carriage 1 has moved from below the metering device to a new apparatus 14 where the die parts 3 and 4 are pulled away from one another. This allows removing the model 19 from the form. After such removing, the form is left to close back and the carriage 1 is moved to the casting apparatus proper. That portion of space 5 which was previously taken by said model 19, is filled there with liquid cast metal. It is clear that said portion of space 5 should open on the form top side through a casting opening.
Carriage 1 moves further while the liquid metal inside the form solidifies and cools. A small expanding during such solidifying is possible. Die parts 3 and 4 can always be moved away from one another against the action of spring 9. After the cooling area, the carriage 1 reaches again an apparatus 14 where the die parts 3 and 4 are again moved away from one another. Both the solidifed cast part and the form material are removed from the hollow space 5 between die parts 3 and 4. Said form material is fed to a recycling device to be used again in the device. When desired the die parts 3 and 4 can be replaced.
The complete installation requires but a minimized energy supply. No energy supply is required to retain die parts 3 and 4 together during the various steps of the complete cycle. This is obtained by means of spring 9 which does still however allow a required expanding of the casting material as it solidifies. The structure of the device for the manufacturing of the casting material is quite simple. The filling of the device when shaping the casting form is also very simple because the form material simply falls by gravity in the space between die parts 3 and 4 and model 19. Moreover said form material is distributed very homogeneously after vibrating and the air present inside space 5 can escape easily.
The above-described device for the manufacturing of a casting form can be mounted in an "in-line" arrangement and in a "revolving" arrangement. In the latter case the forms comprised of the support plate and the die parts mounted thereon are mounted on a rotating turntable instead of on carriages.
The invention is in no way limited to the above embodiments and many changes can be brought therein without departing from the scope of the invention as defined by the appended claims.
For instance the form does not necessarily have to be mounted on a movable support. The form may simply be raised, for example by means of a hoisting device and it is even possible to perform the various operations without moving the form.
The spring which pushes together the die parts does not necessarily have to be a spiral spring. It is for instance also possible to use a plate spring and the spring can also be a draw-spring instead of a compression spring.
Other mechanisms than the damper means described above can be used to insure a smooth closing.
The vibrating mechanism does not have either to be necessarily mounted on the carriage but it can notably also be arranged along the carriage path.
The metering device does not either have to be of the above-described type. The metering can also for instance be made with an Archimedian screw.

Claims

1. Device for the manufacturing of a casting form, which comprises a support, at least two die parts at least one of which is so mounted as to be movable relative to said support, a model of the part to be molded arranged between said parts, means to feed form material between the model and the die parts, and means to retain the die parts temporarily together, in which the means for feeding form material between the model and the die parts comprise a metering mechanism to determine a form material dosis, feeding means to feed form material to the metering mechanism, and a vibrating mechanism which can cause at least one of the parts formed by the support, the die parts and the model to vibrate.

2. Device as defined in claim 1, in which the metering mechanism comprises a tank provided with an outlet, a closure device on said outlet, disconnectable means to feed form material to the tank, means to control said latter-mentioned means to disconnect the feeding to said tank when the desired amount of form material has been fed to said tank, in such a way that the feeding to the tank stops, and means to open said closure device.

3. Device for the manufacturing of a casting form, which comprises a support, at least two die parts at least one of which is so mounted as to be movable relative to said support, a model of the part to be molded arranged between said parts, means to feed from material between the model and the die parts, and means to retain the die parts temporarily together, in which the means to retain the die parts together are formed by at least one spring which is mounted under strain on that unit formed by the support and the die parts mounted thereon, and which always tries to move said die parts towards one another, while the device comprises means to compensate the action of the spring and to move apart and retain spaced temporarily said die parts.

4. Device as defined in claim 3, in which the spring is fixedly mounted between a rim integral with said support and the one die part, while at least one other die part is made fast to the support.

5. Device as defined in either one of claims 3 and 4, in which the means to retain the die parts together comprise a mechanism which insures a smooth engagement of said die parts.

6. Device as defined in claim 5, in which the mechanism insuring a smooth closing of the die parts is a damper.

7. Device as defined in any one of claims 3 to 6, in which the support is movable along a determined path, while the means to move said die parts away from one another are arranged along said path.

8. Device as defined in any one of claims 3 to 7, in which the spring is a metal spring.