NL7904124A - Production of a sand core of complicated form - in box with several components and pattern segments - Google Patents

Abstract

Using a moulding box assembled from a number of components and a number of pattern segments, between which vanes of metal or other material are placed, a core of sand for casting a vane wheel for a pump, is produced. In successive phases, leaving out each time one of a number of segments lying in opposition to each other, the space or spaces remaining are filled with sand, and the core segment obtained is hardened with gas. After the completion of all the core segments and after taking them out, the vanes between the core segments are removed. When the hardened core segments are replaced in the box, the space or spaces formed by leaving out a number of the components of the box, is (are) filled with core sand and hardened with gas so that the core segments form a core which forms a whole. To make it unnecessary to risk damaging the core of a complicated geometrical form, by extracting the vanes from it, and the possibility that the repaired core will produce an imbalanced wheel.

Description

I B. v. O. L L.

I., ITTmE 1873 {

Reg. No. 1 12,698 / Kay. ^ CN [f «/

Partnership

Oldenhof fc Zn. Modelmakerij, in Hengelo Werkvijze for making a sand core.

The invention relates to a method of making a sand core, in particular a sand core of a complicated geometric shape, such as, for example, a second core for the final casting of a paddle for a pump.

It has hitherto been customary to remove the echo segments after forming such a sand core, however, due to their geometric shape, damage to the sand core could not be avoided when these vane segments were removed. Therefore, the sand core had to be updated, which was not only time consuming, but also led to inaccuracies. Often the end product, for example in the present case of an impeller wheel, was found to have unbalances, so that the finished product required additional finishing.

In order to overcome the aforementioned drawbacks, a method is therefore proposed according to the invention, characterized in that in successive phases each time one or a number of opposing model segments is omitted, the space or spaces that are freed up within the core tank with core sand or become are sprayed and the core segments thus obtained are gas-cured, that after completion of all core segments and after removal from the core tray, the blades located between the formed core segments are removed, and that after placement of the formed and hardened core segments in the core box the free space within the core box, obtained by omitting a number of core box parts, with core

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2 sand is sprayed on and then hardened with gas, so that the core segments form an integral sand core.

In the case of large series, the core segments are produced in a separate segment core tray and then sprayed together and gas-hardened after placement in the core tray.

The invention will now be further elucidated on the basis of the description and the accompanying drawings, in which:

Fig. 1 shows the component parts of a core tray, in particular for the formation of a sand core for an impeller wheel; Fig. 2 shows the composite core box with the omission of a number of model segments; Fig. 3 and ^ show how the core box is assembled and in which the already formed core segments are placed; Fig. 5 shows the finally obtained sand core; Fig. 6 shows a molded top box; Fig. 7 shows an assembly of a bottom and top cabinet and the sand core according to Fig. 5; Fig. 8 shows the casting finally obtained; Fig. 9 shows a segment core tray for pre-forming loose core segments.

The following description concerns a method in particular for manufacturing a blade wheel. Fig. 1 shows the various parts 1 to 6 of a core box and five model segments 7 to 11 provided with upright cams 7 'to 11', which in the assembled condition of the core box engage in the holes 12 of the top core box Part 1. 13 denotes a stepped core for forming a hub, the top portion of which, in the assembled state of the core box, engages the central hole 1U of the top core box part 1. In the bottom of the bottom core box - part 6 is a number '04124

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3 arcuate slots 15 in which the scl (see fig. 2) are placed, which are made or any other suitable material. For correct alignment of the core box parts, these are fitted on 5 with cams and recesses 16 and 17

The sand core will now be moved to. In a first phase, the core box is earn * from parts 1 to 6 (see fig. 1) and two mode segments 9 and 10 which are situated one on top of the other are omitted. Core sand is injected through the openings 12 in the core tank part 1 into the space within the core tank, which free space is created by omitting the model segments 9 and 10. 15 9 "and 10" (see fig. 3), which is then gas-fired

Between these shaped sand segments and the adjacent segments are of course the blades 18. V, the core tray is opened and two other superimposed model segments 7 and 11 are taken out, the core tray is reassembled. As in the e phase, the spaces released by removing the model segments are filled with core sand and sand segments 7 "and 11" (see Fig. 3) thus obtained are gas-cured. In a final phase, the core box is opened bet 25 and the model segment 8 is taken out. As in the ongoing phases, the core tank is then assembled, by taking out the model segment 8 space inside the core tank is sprayed with core sand and the sand core 8 "(see fig. 3) thus obtained with gas g. the kernba hardened sand cores or core segments 7M to 11 ", between which there are still five blades 18. By dismantling the core box, the loose core segment can be taken out and the blades 18 can be removed therebetween.

bath original 7904124 1 *

To obtain the sand core shown in FIG. 5, proceed as follows: Using the core tray parts 2, H, 6 and 19 (see FIGS. 3 and k), a core tray is assembled within which the shaped and hardened core segments 7 "to 11" are placed. By omitting the core tray parts 1, 3, 13 and 5, a free space is created within the composite core tray, which is filled with core sand j and subsequently hardened. the core segments f 7 "to 11" form one whole. By omitting the core 13 (see fig. 1) a hub x - '20 is also formed on the sand core, as indicated in fig. Fig. 5- sand core 23 can now be taken out of the core bin.

To cast the product shown in Fig. 8, use is made of a top box 21 and a bottom box 22, as shown in Figs. 6 and 7. After the two cabinets have been formed (fig. 7), the sand core 23 is placed in the recess of the bottom cabinet 22 and the top cabinet 21 is placed on the bottom cabinet, after which the mold is ready for casting. The obtained casting is shown in Fig. 8. When preparing large series of castings, the sand segments are not formed in the core tray composed of the core tray parts 1 to 6, but are formed in a separate segment core tray 2k, as shown in Fig. 9.

After forming the core segments, they must be sprayed together. To this end, use is again made of the composite core tray shown in FIGS. 3 and U, and the forming process proceeds as described above.

Although the present method described relates to the formation of a sand core for an impeller of a pump, the method is not limited solely to this, but can also be used to form any other geometrically complex shape of a sand core.

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Claims (2)

Method according to claim 1, characterized in that the core segments are produced in a separate segment core bin and then placed together in the core bin and sprayed together with gas. 3. Method substantially as described in the description. 790 4 1 24 BATH ORIGINAL