FR2633206A1 - MOLD FOR THE MANUFACTURE OF A METAL PART, USE OF THIS MOLD AND CORRESPONDING MOLDING METHOD - Google Patents

Abstract

The mold comprises a hollow metal frame 3 containing molding sand 5 delimiting the cavity 6, 6 'of the part and at least one cooler 10 made of a metallic material disposed in the molding sand 5 and flush with the surface of the cavity 6, 6 'on a part of this impression corresponding to the hardened zone of the part. The cooler 10 is integral with the frame 3. Preferably, the cooler 10 is removably attached to the frame 3. The invention applies in particular to the casting of camshafts for motor vehicles.

Description

1. The invention relates to a mold comprising

  coolers for the production of a metal part-

  lique having at least one hard surface area

by quenching during molding.

  Parts are known, in particular parts used in the automotive industry, such as camshafts, which have certain zones whose surface hardness is higher than the

  hardness of other parts of the part.

  In the case of soft cast iron camshafts

  strips, an increase in hardness and therefore in wear resistance of the cams is obtained by an increase in the cooling rate of the liquid iron in the zones corresponding to the periphery of the cams. The

  rapid cooling of the pig iron in these areas

  evokes the local formation of high hardness white cast iron. Sand casting of the piece is carried out

  in an imprint formed inside the sand,

  pleating a hollow metal frame which is generally-

  made up of several parts. Cool it down

  Fast or quenching of the cast iron is ensured in the areas of the cavity corresponding to the periphery of the cams by metal coolers flush with the surface of the cavity. The coolers have a surface intended to come into contact with the liquid iron whose shape corresponds to that of a part

  at least from the outer surface of the cam.

  The mold is generally constituted by two stackable half-molds which each have a

  cavity corresponding to a half-cavity of the part.

  In the case of known and used techniques

  Currently, the chillers are either

  with separate parts linked together to

  build clusters of several coolers.

  In the first case, each of the coolers

  seurs corresponds to half the periphery of a

  cam and must be placed in a semi-mold

read beforehand.

  In the second case, the cooling cluster

  sors is deposited on the model plate before the realization

sation of the half-mold.

  In both cases, the coolers

  tituent independent elements that it is necessary to set up very precisely in the mold before or after filling it with sand and prior to each casting. At the end of the molding cycle, the coolers are removed with the sand from which they are collected. Coolers

  must be sorted since they are not all identi-

  ques. then prepared for the following molding operation

  boasts. All of these cooler installation and recovery operations are very labor-intensive and, because the coolers are

  put in the manual way position, it is very diffi-

  eyelash otherwise impossible to obtain a good closure

  of the two half-molds. It is therefore necessary to perform

  kill a grinding of the joint plane, parts obtained by molding, which leads to the formation of primers of

rupture on these parts.

  The object of the invention is therefore to propose a mold for the manufacture of a metal part having at least one surface area hardened by

  hardening during molding, comprising a metall chassis

  hollow liner containing delimited molding sand

  both the footprint of the room and at least one cooling

  seur in a metallic material placed in the molding sand and flush with the surface of the imprint in a part of this imprint corresponding to the hardened zone of the part, this mold making it possible to avoid long and costly operations of positioning and cooler recovery. For this reason. the cooler is integral

of the chassis.

  In order to clearly understand the invention,

  we will now describe, by way of nonlimited example

  tative, with reference to the appended figures, an embodiment of a mold according to the invention intended for the manufacture of camshafts of motor vehicles.

  Figure 1 is a perspective view re-

  presenting the lower part of the mold according to the

vention.

  Figure 2 is a perspective view re-

  presenting the upper part of the mold according to the

  vention. FIG. 3 is a perspective view of a cooler of the mold shown in FIGS. 1 and 2.

  Figure 4 is an exploded perspective view

  tee showing how a cooler is attached

on the mold chassis.

  Figure 5 is a half view in elevation

  of a cooler according to a variant.

  The mold according to the invention consists of a lower half-mold 1 shown in the figure

  1 and an upper half-mold 2 shown in the fig-

re 2.

  The lower half-mold 1 comprises a half

  chassis 3 with rectangular section and the half-mold above

  perieure 2 a half-frame 4, also with cross-section

  tangular, the sections of the half-frames 3 and 4 being

perfectly stackable.

  The steel half-frames 3 and 4, produced in the hollow form, are filled with sand 5 in which two half-impressions 6. 6 have been formed for the molding of two camshafts of motor vehicles.

  These half-impressions are made in place

  placing the half-frames on model plates and filling them either with green sand or with

sand bound by a resin.

  Also provided in the half-mold

  2 a cavity 7 communicating with the footprints

  your 6, 6 'to form a reserve flyweight

  metal intended to compensate for shrinkage during the

  lage and a filling cup 8 passing through the

  upper half-mold 2 over its entire thickness.

  Finally, we set up a flow channel 9 in

  the lower half-mold 1 in accordance with the end

filling cup 8.

  Metal coolers 10 general-

  consisting of steel plates are arranged in the lower half-mold 1 and in the upper half-mold 2, in corresponding positions, at the molding zones of the cams of the cavities 6 and 6 ′ of the two camshafts . Coolers 10

  have 13 flush cooling surfaces

  rant the surface of the imprints 6 and B 'in zones corresponding to the peripheral part of the cams,

  we want to ensure quenching during molding.

  As can be seen in FIGS. 3 and 4, the coolers 10 according to the invention are fixed to the corresponding half-chassis 3 and 4, of which they remain integral during all the stages of the process

molding.

  Each of the coolers 10 consists of a steel plate having two recesses intended to constitute the cooling surfaces 13 at the periphery of the cam molding zones. The coolers 10 are arranged transversely inside the half-chassis 3 and 4 between the two long sides of these half-chissis. Coolers

  have a length, in the direction trans-

  slightly larger than the internal width of the

  half frame and the corresponding sides of the half

  chassis 3 and 4 have assembly grooves 14

  (figure 4) in which come to engage in the world

  the ends of the coolers 10. The sides

  half-frames 3 and 4 are drilled at the bottom of the groove

  res 14 of two holes 15 and 16 and the coolers 10 have, on each of their lateral sides coming to engage in the grooves 14, a tapped hole 17 and

a smooth hole 18.

  As seen in Figure 4, when

  that the cooler 10 is engaged in the half

  chassis 3 or 4, the tapped hole 17 is in agreement

  with hole 15 and hole 18 with hole 16.

  The assembly and positioning of the cooler

  disseur are insured on each of its lateral sides

by a screw 20 and a pin 21.

  The pin 21. engaged in the holes 16 and

  18 in agreement, ensures the positioning of the cooling

  straightener in the groove 14 and the screw 20. engaged in the opening 15 and screwed into the tapped hole 17,

  ensures the assembly of the cooler 10 on the half

frame.

  In Figure 5, there is shown a cooling

  straightener 10 'according to an alternative embodiment comprising

  both a recess 13 'of reduced amplitude. When the two parts of the mold are joined, the recesses 13 'of the corresponding coolers 10' do not surround

  only part of the periphery of the cam, which

  requires hardening and hardening of only part of the cam. The coolers 10 ′ are fixed to the corresponding half-frames via their lateral sides of reduced height in which

  17 'threaded holes are provided.

  Note that the screw assembly mode of the coolers, as shown in the figure

  4, allows to realize the coolers and the half

  chassis in different materials. The mold frame may for example be made of ordinary steel and

  alloy steel coolers or any other material

metallic material.

  On the other hand, this method of assembly allows

  easily replace used coolers.

  We will now describe a complete cycle of

  molding using the mold according to the invention

  tion. There are half-molds 1 and 2 made up of the half-frames and the coolers attached to

these half chassis.

  The manufacturing of the mold is carried out by

  placing each of the half-frames on the model plate cor-

  respondent and filling the half

  chassis by molding sand. So we don't have to ef-

  during this operation, install and adjust the coolers which are integral with the half-chassis. The mold is then assembled by superimposing the two half-molds 1 and 2, then the mold is filled with the cup 8. The cast parts are then cooled to a temperature between 700 and 800 * before qu 'The mold is removed by unhooking the mold. - The half-molds 1 and 2 are then ready for a new molding operation. The coolers being integral with the chassis of the half-molds, it is not necessary to carry out, as in the prior art, the recovery of the coolers in the molding sand, the sorting of these coolers then the placing in

place these in the mold.

  In the case of mass production on a cycle site, the chissis-cooler assemblies are cooled after release by an air flow to bring the half-molds to a temperature allowing

  carry out the mold preparation operations.

  When the release takes place while the cast iron is at a temperature between 700 and 800, the coolers are then at a temperature of around 200 ° C. Cooling by an air flow at 10 * c

  allows to pass the temperature of these coolers

  dissectors at a temperature which can be understood

  between 30 and 50'C in a very short time.

  We see that the main advantages of the

  the following the invention are to avoid operations

  time-consuming and costly to set up and recover

  tion of the coolers, these remaining linked to the chas-

mold sis.

  On the other hand, in the case where the mold is

  consisting of two half-molds,

  maintains very good contact between the two parts of the mold, which limits the formation of burrs at the joint plane. This avoids having to perform

  grinding of the joint plane, which results in improved

  quality improvement, grinding resulting in

mation of primers of rupture.

  In the case where the coolers are detachably connected to the chassis, for example by screws, these coolers can be replaced in the event of wear. In addition, the cooler and the mold chassis

  may be made of different materials.

  The invention is not limited to the mode of realization

which has been described.

  It applies as well in the case of a mold made in a single part as in the case of a mold in several parts and consisting for example of

  half-molds each comprising a half-frame.

  The invention applies whatever the name

  number of parts which are cast in a mold and whatever the extent of the surface to be quenched

the periphery of these rooms.

  The invention applies both in the case of conventional foundry and in the case where

  uses the lost model process (PMP).

  The invention applies not only to the mold.

  lage of the camshafts but also in the molding of other cast iron parts or even in the molding of metal parts in materials other than cast iron, which can be hardened by cooling

  fast or hardening of certain areas, during the

age. g

Claims (13)

  1.- Mold for the manufacture of a metal part having at least one surface area hardened by quenching during molding comprising a hollow metal frame (3, 4) containing molding sand (5) delimiting the imprint (6, 6 ') from the room   and at least one cooler (10) made of a metallic material   metal sheet placed in the molding sand (5) and af-   flowering the surface of the imprint (6, 6 ') on a part (13) of this imprint corresponding to the area   hardened part, characterized in that the re-   cooler (10) is integral with the chassis (3, 4).   2.- mold according to claim 1, comprising-   both two half-molds (1, 2) each comprising a half-frame (3, 4), characterized in that on each of the half-frames (3, 4) is fixed at least one cooler (10).   3.- Mold according to claim 2,   bearing half-chassis (3, 4) with rectangular section   re, characterized in that the coolers (10) are formed in the form of plates fixed transversely in the half-frames (3, 4) between their great sides.   4.- Mold according to any of the   vendications 1, 2 and 3, characterized in that the coolers (10) are removably attached on the chassis (3, 4).   5.- Mold according to claim 4, charac-   terrified by the fact that the coolers (10) are   fixed by screws (20) to the frame (3, 4).   6.- Mold according to claim 4, ca-   characterized by the fact that the coolers (10) are engaged by their ends in grooves (14)   machined on surfaces facing the chassis (3, 4).   7.- Mold according to any of the   vendications 1 to 6, characterized in that the chassis (3, 4) on the one hand and the cooler (10)   on the other hand are made of different materials.   8.- mold according to claim 7, characterized in that the frame (3. 4) is made of steel   ordinary and the cooler (10) made of alloy steel.   9.- Mold according to any of the   vendications 1 to 8, characterized in that the cooler (10) has at least one recess (13)   constituting a corresponding cooling surface   to the hardened area of the room.   10.- Mold according to claim 9, ca-   characterized by the fact that the recess (13 ') of the cooling   disseur (10 ') corresponds to only part of the   periphery of the part in its hardened area.   11.- Method of molding a metal part   that having at least one surface area hardened by quenching consisting in making an imprint (6, 6 ') of the part in sand (5) filling a frame   metallic (3. 4) in which are arranged   coolers (10), pouring the liquid metal into the cavity and demolding by unhooking the mold after cooling and solidification of the   liquid metal, characterized in that after deco-   chage we realize the simultaneous cooling of the chas-   sis (3, 4) and coolers (10).   12.- Method according to claim 11,   characterized by the fact that the cooling takes place   chassis (3, 4) and coolers (10) by circulation of an air stream.   13.- Use of a mold according to one   any of claims 1 to 11 for the manufacture of   cation of cast iron camshafts for motor vehicles   mobile whose cams are hardened by quenching.