FR2630942A1 - FOUNDRY PIECE PROVIDED WITH A BREAKABLE PELLET - Google Patents

Abstract

The invention relates to a casting (1) comprising a body having a wall (2) equipped with at least one slug (3) breakable by knocking so as to expose an orifice (4) through said wall (2) in place of said slug (3). The slug (3) is fixed to a resistant zone (5) of the wall (2) of the body by means of a breakable zone (6) surrounded by said resistant zone (5), the cross-section of this breakable zone (6), which connects the slug (3) to the resistant zone, being substantially reduced in relation to the cross-section of this resistant zone (5) and in relation to the cross-section of the slug (3). Moreover, the slug (3) is located completely outside the space defined by the two planes P1 and P2 between which the resistant zone (5) is inscribed.

Description

Foundry piece provided with a knockout The present invention

  relates to foundry pieces of the type comprising a body having a wall provided with at least one pellet knockable so as to release an opening through said

  wall in place of said patch.

  It finds a particularly important, although not exclusive, application in the field of metal cast iron parts, and more particularly

  manhole covers intended to close openings

  tures giving access to a pipe, a sewer or a gallery. Road regulations are very different depending on the country and / or the city of the same country. Certain agglomerations require, in fact, ventilated manholes (provided with holes

  while others want her-

  metics. Very early on, founders, obliged to provide these two types of manhole covers, designed manholes comprising knockouts which can be knocked down on demand, and designed to constitute ventilated manholes (knockout knockouts released) or airtight manholes (knockout knockouts in place ); such an arrangement therefore makes it possible, with the same mold, to produce

the two types of looks.

  To date, these knockouts with knockouts have been produced using the technique of providing an annular groove leaving a frangible zone in the thickness of the cast iron wall and around the periphery of the pellet to be broken. However, the thickness of this frangible zone cannot be satisfactorily controlled by the technique used, in which a mold is produced in two parts, closing one over the other; the dimensional tolerances inherent on the one hand in the manufacture of the two parts of the mold and on the other hand in the relative positioning of the two parts of the mold can cause significant variations in thickness of the frangible zone, therefore variations

  important of the section of material to break.

  There is a significant risk of obtaining, after pouring the cast iron, a manhole whose pellet cannot be knocked out (thickness of the frangible zone too large) which prohibits the production of ventilated manholes, or on the contrary a manhole whose tablet does not have the required solidity (thickness of the frangible zone too low), which prohibits manufacturing

hermetic looks.

  The present invention aims to provide a foundry piece of the above type defined which meets better than those previously known the requirements of practice, in particular in that it has a knockout having, on the one hand, the characteristic of being able to be released by percussion. for sure, and on the other hand, the characteristic of being able to stay in

place for sure.

  Furthermore, the effort required to release the pellet can be known and can be calibrated to be

  identical on all casting parts to be cast.

  The manufacture of the parts according to the invention is of a very simple, inexpensive implementation, and makes it possible to obtain des.pièces without waste, with a large

reliability and good quality.

  For this purpose, the invention essentially provides a foundry piece of the type defined above, characterized in that the pellet is integral with a resistant zone of the wall of the body by means of

  a frangible zone surrounded by said resistant zone

  aunt, the section of this frangible zone connecting the patch to the resistant zone being substantially reduced compared to the section of this resistant zone and compared to the section of said

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  pellet, and in that the pellet is entirely situated outside the space defined by the two planes P1 and P2 between which the resistant zone is inscribed. In advantageous embodiments, use is also made of one and / or the other of the following arrangements: - The frangible zone is a hollow cylinder or a

  hollow prism and the pellet is respectively sensitive

clearly cylindrical or prismatic.

  - The part is made of cast iron.

  The invention will be better understood on reading

  the following description of particular modes of

  embodiment, given by way of nonlimiting example.

  The description refers to the drawings which

  accompany it on which - Figure 1 is an elevational section of a foundry piece according to the invention, provided with a cylindrical pellet knockable by percussion; - Figure 2 is a section along II-II Figure 1; - Figure 3 is a section of another foundry piece, according to the invention, provided with a prismatic pellet; - Figure 4 shows, in section under the same conditions as in Figure 1, a foundry piece according to the invention, provided with two pellets, as well as the mold in which it was cast; - Figure 5, shows an enlarged sectional view, in elevation, part of the foundry part of Figure 4, produced in the case of a centering defect of its manufacturing mold; - Figure 6 is a section along VI-VI

figure 5.

  Figures 1, 2 and 3 show a foundry piece 1 comprising a body having a wall 2 provided with at least one pellet 3, knockable by percussion so as to release an opening 4 through said wall 2 in place of said pellet 3. The pellet 3 is secured to a resistant zone 5 of the wall 2 of the body 1 via a frangible zone 6

  surrounded by said resistant zone 5.

  The section of this frangible zone 6, that is to say

  say the section connecting the patch 3 to the resistant zone 5, is substantially reduced compared to the section of the resistant zone 5 and, compared to the

section of the pellet itself.

  The patch 3 is entirely located outside the space defined by the two substantially flat surfaces P1 and P2 between which is the resistant zone 5. In other words, the face 11 of the patch located on the side of the wall 2 found at a distance h from the surface P2, of value greater than or equal to 0, whatever the mold closing faults. FIG. 4, in which the same reference numerals designate the same members as in FIG. 1, shows a foundry part 1 comprising two knockouts 3, this part being represented inside its manufacturing mold 15. The mold 15

  has a lower half 16 and a half

  upper part 17, for example removable by means of

  medial of handles 18. Inlets 19 are provided in the mold for casting the cast iron of the foundry piece 1. The two mold parts 16 and 17 are shaped to give the desired shape to the piece of

foundry 1.

  The frangible zone 6 of each patch 3 has an external face 20 and an internal face 22, these two external faces 20 and internal 22 having a draft, or surface configuration, suitable for promoting the

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  demoulding. In the case of a substantially cylindrical pellet for example, the foundry part has, on the side of the external face 20 of the frangible zone 6, a part in relief with a conical wall, and, on the side of the internal face 22 of the frangible zone 6, a hollow part with a conical wall, the faces 20 and 22 being

  at least approximately parallel.

  Thanks to the invention it is understood that, as long as the imprecision in the making of the mold is less than the quantity h, in the direction perpendicular to the plane of the casting, the section of the frangible zone 6 remains constant, and of this fact, the properties provided by this frangible zone (possibility of releasing the tablet by percussion for sure or possibility of considering the tablet in place as

  part) remain constant.

  Still thanks to the invention, and as can be seen in FIGS. 5 and 6 in which the same reference numerals designate the same members as in FIG. 1, it can be seen that a decentering of the two half-parts of the mold does not not modify the value of the section of frangible zone 6 whose properties

remain constant.

  Taking into account the fact that the properties of the frangible zone 6 are not altered either by an imprecision in the making of the mold, nor by a decentering of its two constituent half-parts, the reliability of the ventilable foundry part, whether in the case where one must obtain a "ventilated" part or in the case where one must obtain a "hermetic" part, is greater than the reliability of ventilable foundry parts known to date, and this because of the possibilities of the pad which either is released "reliably" or is left in place also

reliable".

  As is obvious and as it follows from the above, the invention is in no way limited to the embodiments more specifically described;

  on the contrary, it embraces all its variants.

Claims (5)

  1. Foundry piece (1) comprising a body having a wall (2) provided with at least one pellet (3) knocked out by percussion so as to release an opening (4) through said wall (2) instead of said patch (3), characterized in that the patch (3) is integral with a resistant zone (5) of the wall (2) of the body via a frangible zone (6) surrounded by said zone resistant (5), the section of this frangible zone (6), connecting the patch (3) to the resistant zone, being substantially lessened with respect to the section of this resistant zone (5) and with respect to the section of the patch (3), and in that the patch (3) is entirely located outside the space defined by the two planes P1 and P2 between which the zone is inscribed resistant (5).   2. Foundry part according to claim 1, characterized in that the frangible zone (6) is a hollow cylinder and the pellet (3) is substantially cylindrical. 3. Foundry part according to claim 1, characterized in that the frangible zone (6) is a   hollow prism and the pellet is substantially taken-   matic. 4. Foundry part according to claim 1, characterized in that the ftrangible zone (6) has an external face (20) and an internal face (22), these two external (20) and internal (22) faces being conical and parallel, at least approximately, so that promote release.   5. Foundry part according to any one of   previous claims, characterized in that the room is a pavement look.