FR2824503A1 - Production of sewage system manholes, by rotation molding, has a planning process to select the mold components for assembly according to the manhole specifications for a wide range of manholes with fewer mold components - Google Patents

Abstract

To shape a manhole for sewage channel systems, by rotation molding, a planning process determines the assembly of the mold according to the manhole specifications (111). The mold components are selected (11), assembled (12) in the required configuration for the manholes to be molded (13). The mold has a variety of half-shells, for selection according to the geometry of the manhole structure.

Description

and 0.5 times the length L.

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  Method of manufacturing manholes by rotational molding, mold elements,

molds and corresponding manholes.

  The field of the invention is that of the production of manholes for pipes, and in particular drainage pipes. The manholes, sometimes also called manholes, allow on the one hand to connect together several (conventionally 2 or 3) piping elements, and on the other hand to access these

  piping, for control and maintenance.

  Generally, these manholes are made of concrete. However, this classic technique has many disadvantages, such as the weight (making handling, storage and installation difficult) and the brittleness (impact resistance

  and resistance to certain chemicals, ...).

  In addition, the installers of pipelines need a high number of types of manhole, according to the configurations of the ground, the network to install, ... The required heights are variable, as well as the number and the direction of the end fittings connection, or even the diameter of these end pieces This requires, for the manhole manufacturer, to have a high number of molds (as many as types

look required).

  However, we know that the cost of manufacturing a mold is often very high. Manufacturers are therefore led either to limit the number of types of products

  available, or to sell them at a high price to amortize manufacturing costs.

  Clearly, these two alternatives are not acceptable from a commercial point of view. The present invention aims in particular to overcome these drawbacks

state of the art.

  More specifically, an objective of the invention is to provide a method of manufacturing manholes, making it possible to produce a large number of types of manholes,

an acceptable cost price.

  Another objective of the invention is to provide such a method, making it possible to produce lighter and more resistant manholes than conventional concrete manholes.

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  These objectives, as well as others which will appear subsequently, are achieved according to the invention, using a manufacturing process by rotational molding of manholes for pipeline, comprising the following steps: - production of a set of 'mold elements intended to be assembled, among which: - at least two lower elements, having at least two end fittings for piping elements defining separate angles for each of said lower elements; at least two intermediate elements; - at least one upper element; preparation of a mold, by assembly: - of a lower element; optionally at least one upper element; and 1S - of an upper element, said mold elements comprising complementary pre-centering means, so as to allow easy and precise assembly of each of said mold elements with a neighboring mold element; manufacture of at least one manhole, using said mold, by rotational molding, so that a large number of types of manhole can be manufactured, from a

  limited number of mold elements.

  Thus, it is not necessary to have as many molds as there are different looks. Each mold is formed from a set of mold elements, most of which can be used to make several types of manhole. The way in which the molds are defined, produced and assembled must, however, comply with specific rules. In particular, to allow easy and efficient assembly of the mold elements, it is necessary to provide precentring means (complementary male / female elements, for example), which guide one mold element towards the other in the

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  good assembly position, and keep them in this position, until

  final assembly using yokes and / or screws / nuts.

  Likewise, advantageously, said mold elements are designed so that the transitions between two neighboring mold elements are defined, as far as possible, in regions corresponding to generators and / or outputs of

  radius of the surface of the corresponding gaze.

  This allows in particular to facilitate and optimize the release of the parts.

  Preferably, at least said intermediate elements (but preferably also the other mold elements) have a crenellated appearance capable of reinforcing them, by an alternating succession of rings of a first diameter.

  and a ring of a second diameter, greater than said first diameter.

  In this case, the assembly area with a neighboring mold element

  advantageously corresponds to a ring of second diameter.

  According to a particular aspect of the invention, at least one of said lower elements has holding and / or fixing feet, having an opening, inside said manhole. In this case, provision is advantageously made after

  molding, the establishment of means for closing said opening.

  Said sealing means may in particular comprise a plug

  forced in, and / or a material filling the interior of the corresponding foot.

  According to an advantageous characteristic of the invention, at least some of said mold elements are themselves formed from at least two half-shells, one

  said shells being common to at least two separate mold elements.

  It is thus still possible to reduce the number of parts necessary for

  make a plurality of separate molds.

  Similarly, provision is advantageously made for tool sleeves to form pipe end pieces, which can be mounted on the

  minus two lower mold elements.

  According to a particular embodiment of the invention, said mold elements comprise at least: - the lower elements belonging to the group comprising:

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  - a viewing shell with two aligned tips (A); - a viewing shell with two end pieces forming an angle of

  (A1);

  - a viewing shell with two end pieces forming an angle of

120 (A2);

  - a viewing shell with three tips (Y) having an angle of 135 to the right (A4D); - a viewing shell with three tips (Y) having an angle of 135 to the left (A4G); - the intermediate elements belonging to the group comprising: - a shell of approximately 400 mm in height (B); a shell about 360 mm high (C); - a shell about 700 mm high (E); - a shell about 350 mm high (F); - the upper elements belonging to the group comprising: - a shell having two rings (D);

  - a shell with four rings (D1).

  Preferably, said shells A1 and A2 have a common half-shell. The invention also relates to the various mold elements (as well as the half-shells and the sleeves) used by the manufacturing process described above, as well as the corresponding molds, formed by the assembly of at least two

  mold elements, and manholes made using this manufacturing process.

  Other characteristics and advantages of the invention will appear more

  clearly on reading the following description of a preferred embodiment

  of the invention, given by way of a simple illustrative and nonlimiting example, and of the appended drawings among which: - Figure 1 is a general block diagram of the process of the invention; - Figure 2 is a first example of manhole manufactured using the method of Figure 1;

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  - Figure 3 is a second example of manhole manufactured using the method of Figure 1; - Figures 4A to 4C illustrate the embodiment in two half-shells of

  two lower mold elements.

  As mentioned above, the novelty of the invention res i in particular in an original approach to the production of molds, from a set of elements

  mold, for the manufacture of manholes for pipe by rotational molding.

  According to the invention, the production of these mold elements provides for the presence

  pre-centering means, to allow easy and precise assembly.

  To allow easy demoulding and ensure the production of good quality parts, the definition of mold elements must comply with precise rules. In particular, we make sure that the transition zones between two mold elements

  corresponding to generations or to ray departures.

  Figure 1 illustrates, in the form of a general block diagram, the main aspects of the invention, which can be broken down into three main parts: - production of the mold elements (11); - assembly of a mold from mold elements (12);

- manufacture of manholes (13).

  An objective of the invention is to allow the production of a large number of types of gaze. It is therefore first of all necessary to identify (111) these

  different types of manhole (including height, number and orientation of end caps).

  For example, we would like to have 6 heights, between 1,250 and 3,050 mm. Each height can be equipped with two aligned ends, or forming an angle of 150 (30) or 120 (60), or three ends, defining either angles of 135 (45) to

right or left.

  In other words, it is. in this example, wanted to be able to make 30 different types of look. In practice, this number is multiplied several times, by

  the addition of various variants, which should be found on most looks.

  We understand that it is not economically possible to create as many separate molds.

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  We therefore analyze the different desired molds, to decompose them (112) into several mold elements, at least some of which will be common to several molds. As shown in FIGS. 2 and 3, provision is made in particular: - an upper mold element 21; - Several intermediate mold elements 22, and 224, which can be combined (Figure 2) or completely absent (Figure 3); - Several lower mold elements 23, corresponding to the different

tip variants.

  This decomposition into mold elements is not immediate. In fact, in order to obtain effective demolding, the inventor observed that it was desirable to take into account the generatrices and the radius outputs (113) of the various curves, and to ensure that, as much as possible, they correspond to edges of elements

of mold.

  Still with the aim of reducing the number of parts required for the different types of manhole, we observe that certain mold elements, although distinct, have a common part. In this case, the mold element is broken down into two half-shells (114), one of which is common to at least two mold elements. This is for example illustrated by FIGS. 4A to 4C. The half-shell of FIG. 4B can be associated: - with the half-shell of FIG. 4A, to form an angle of 150;

  - to the half-shell of FIG. 4C, to form an angle of 120.

  It will be noted that each mold element, or each half-shell can be produced in a single part (case of the half-shell in FIG. 4B) or in several parts. Thus, the half-shells of FIGS. 4A and 4C have two parts more

a sleeve.

  Indeed, the sleeves, which allow the molding of the tips, are the same on most manholes. In the example described, they successively have three diameters, in order to be able to adapt to three types of connection tulip (the unused parts being able to be cut). It is possible to

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  use on several molds: they are therefore produced (115) independently, to be

  then adapted to the desired mold element.

  The assembly of the mold elements must be precise, in order to obtain clean, solid and easily demouldable products. Provision is therefore made for the presence of pre-centering means (116), which facilitates the guidance and then the assembly of the parts of the

  mold (for example in the form of complementary male / female means).

  Then, we make the different mold elements, half-shells,

  sleeves, ... (117) previously defined.

  It is then possible to prepare a mold (12). Depending on the type 121 of look desired and the decomposition 122 carried out, the assembly (123) of the mold elements is first carried out in several parts, and in particular of the element

  lower, by assembling the half-shells and / or the sleeves.

  Then the pre-assembly 124 of the different mold elements is carried out,

  using the pre-centering means, to obtain the desired mold.

  The assembly is then consolidated (125), using screeds and / or a

  secured by screws and nuts. The mold is then ready for use.

  It only remains to manufacture (13) the desired number of manholes, by rotational molding. We then disassemble the mold, and we are immediately ready to make a

  new series of another type of gaze (14).

  Recall that rotational molding, or rotational molding, uses a solid polymer powder. The material to be molded is introduced into a hollow and closed mold which rotates around two perpendicular axes. On contact with the hot wall, the thermoplastic resin melts and adheres to it. The molds are then cooled and the hollow body is removed from the mold. The molding cycle is as follows: a) loading the mold: a given quantity of high density polyethylene powder (for example) is placed in the cold mold. This quantity determines the weight of the part (losses are non-existent), and the thickness of its walls. I1

  then only remains to lock the mold.

  b) heating: during this heating, the mold is animated by a movement of

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  rotation around two perpendicular axes: the primary axis and the secondary axis. This rotational movement is slow (it is not a centrifugation) and allows the powder to fall to the bottom of the mold while continuing to cover the walls by progressive melting. It takes about 3 minutes of heating per mm of workpiece thickness. c) cooling: this operation follows the heating cycle and must take place when the high density polyethylene is completely melted. The mold is then placed in a cooling chamber, in which its temperature is lowered using a fine spray of water and / or a

cold air flow.

  A particular example of implementation of the method is described below.

  presented above, in relation to FIGS. 2 to 4C.

  Figure 2 shows a large manhole (3 050 mm) produced using a mold comprising 6 mold elements: - A: lower element; - B: 400 mm high intermediate element; - C: intermediate element 360 mm high; - E: intermediate element 690 mm high; - F: intermediate element 350 mm high;

- D: upper element.

  By playing on the number and selection of intermediate elements, one can obtain a high number of possible heights for the molds. For example, in the case of FIG. 3, only the elements A and D are used (without element

  intermediate) the smallest size (1250 mm) is obtained.

  More generally, the following manholes can be distinguished: - A + D (height: around 1,250 mm); - A + B + D (height: approximately 1,650 mm); - A + B + C + D (height: approximately 2,010 mm); - A + B + C + F + D (height: approximately 2,350 mm); A + B + C + E + D (height: about 2,700 mm);

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  - A + B + C + E + F + D (height: around 3 050 mm).

  Other combinations are possible.

  Several interchangeable lower elements are provided, in order to be able to achieve all heights in all versions: - A: lower shell for straight sight; - A1: lower shell for viewing angle 150 (30); - A2: lower shell for viewing angle of 120 (60); - A4D: lower shell for viewing angle 135 (45) right; - A4G: lower shell for viewing at angle of 135 (45) on the left. As illustrated by FIGS. 4A to 4C, the shells A1 and A2 have a common half-shell (FIG. 4B) which can be associated with the half-shell with

    (Figure 4A) or the half-shell at 120 (Figure 4C).

  The half-shells of FIGS. 4A and 4C are formed from two assembled parts and from a sleeve 41. The same sleeve is found on different lower elements. It is therefore expected that the sleeves are produced independently,

  to be associated indifferently with one or the other of the lower elements to be used.

  Each sleeve 41 comprises three portions 411, 412 and 413, corresponding to different diameters. They are advantageously frustoconical to facilitate the nesting of tulips. However, due to the thickness differences inherent in rotational molding technology (conventionally of the order of 1%), there are cases where assembly is not easy, if not impossible. A solution to this particular problem is proposed in a patent application in the name of the same owner as the

this patent application.

  The lower part has, in addition to two or three sleeves 41 for the end pieces, feet 42 which allow, on the one hand, the maintenance in a standing position and the fixing to the ground, using concrete. The opening 43 allows the passage of concrete, and

strengthens solidarity.

  Seen from the inside, each leg also has an opening on the top

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  (this is inherent in rotational molding technology). A means is provided for closing this opening (frustoconical plug, insert, for example by gluing, etc.). It is also possible to provide for filling the inside of the feet, for example with polyurethane foam, sand, concrete. The longitudinal parts of the various elements are formed by a succession of rings of a first width 44 and of a second width 45

  (defining, in section, slots).

  We thus obtain a good solidity and a good rigidity of the looks, which we

  would not have been obtained with only cylindrical elements.

  The separations 46 between the different mold elements are made on the

45 and larger rings.

  The upper element A ends in a part 47 which is narrower than the rest of the manhole, which can be fitted with a closure means (cover). It is possible to cut part 47 at any level, to obtain a precise adjustment of the

look height.

  Ears 48 have also been provided, allowing easy handling of the manholes.

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Claims (13)

  1. A method of manufacturing by rotational molding of manholes for pipeline, characterized in that it comprises the following stages: - production of a set of mold elements intended to be assembled, among which: - at least two elements lower, having at least two ends for connection to piping elements defining separate angles for each of said lower elements; - at least two intermediate elements; - at least one upper element; - preparation of a mold, by assembly: - of a lower element; - possibly at least one upper element; and - of an upper element, the said mold elements comprising complementary complementary means, so as to allow easy and precise assembly of each of said mold elements with a neighboring mold element; manufacture of at least one manhole, using said mold, by rotational molding, so that a large number of types of manhole can be manufactured, from a   limited number of mold elements.   2. Method according to claim 1, characterized in that said mold elements are designed so that the transitions between two neighboring mold elements are defined, as far as possible, in regions corresponding to   generators and / or ray exits from the surface of the corresponding manhole.   3. Method according to claim 2, characterized in that at least said intermediate elements have a crenellated appearance capable of reinforcing them, by an alternating succession of rings of a first diameter and of ring of a second diameter, greater than said first diameter, and in that the assembly zone with a neighboring mold element corresponds to a second diameter ring.   4. Method according to any one of claims 1 to 3, characterized in that   that at least one of said lower elements have holding and / or fixing feet, having an opening, inside said manhole, and in that provision is made, after molding, for the installation of sealing means of said opening.   5. Method according to claim 4, characterized in that said means   shutters include a press-in plug.   6. Method according to any one of claims 4 and 5 'characterized in that   that said sealing means comprise a material filling the interior of the corresponding foot.   7. Method according to any one of claims 1 to 6, characterized in that   that at least some of said mold elements are themselves formed from at least two half-shells, one of said shells being common to at least two separate mold elements.   8. Method according to any one of claims 1 to 7, characterized in that   said mold elements comprise at least: - the lower elements belonging to the group comprising: - a viewing shell with two aligned end pieces (A); - a viewing shell with two end pieces forming an angle of   (A1);   - a viewing shell with two end pieces forming an angle of   (A2);   a viewing shell with three tips (Y) having an angle of 135 to the right (A4D); - a viewing shell with three tips (Y) having an angle of 135 to the left (A4G); - the intermediate elements belonging to the group comprising: - a shell of approximately 400 mm in height (B); 13 2824503   - a shell about 360 mm high (C); - a shell about 700 mrn high (E); - a shell about 350 mm high (F); the upper elements belonging to the group comprising: S - a shell having two rings (D);   - a shell with four rings (D1).   9. Method according to claims 7 and 8, characterized in that said shells   A1 and A2 have a common half-shell.   10. Method according to any one of claims 1 to 9, characterized in that   that we have tool sleeves to form pipe fittings, which   can be mounted on at least two lower mold elements.   11. Mold element used by the manufacturing process according to any one   of claims 1 to 10, characterized in that it is intended to be assembled with at   at least one other mold element to form a manhole mold.   12. Mold used by the manufacturing process according to any one of   Claims 1 to 10, characterized in that it is formed by the assembly of at least two mold elements.   13. Manhole manufactured using the manufacturing process according to any one of