Assembly for manufacturing a metal part and use of such an assembly

Abstract

A manufacturing assembly for manufacturing a metal part comprises a flattening module having a trolley and at least one pressing roller. The flattening module is movable along a hemming of the metal part. The flattening module comprises at least one pressing actuator that is arranged to move the at least one pressing roller in a determined pressing direction relative to the trolley and to place the pressure roller bearing against the free surface such that the at least one pressing roller exerts pressure on the free surface in said determined pressing direction. The pressure increases auto-adaptively with an altitude of the free surface in a direction opposite the determined pressing direction.

Claims

1. A manufacturing assembly for manufacturing a metal part, the manufacturing assembly comprising: a chassis provided with a station that receives the metal part; a flattening module that includes a trolley and the flattening module including at least one pressing roller connected to the trolley, the metal part having two edges hemmed to one another, the two edges hemmed to one another defining a hemming line having a free surface; a longitudinal drive arranged to move the flattening module relative to the chassis along the hemming line when the metal part is at the station; and the flattening module including at least one pressing actuator that is arranged to move the at least one pressing roller in a determined pressing direction relative to the trolley and to place the at least one pressing roller to bear against the free surface such that the at least one pressing roller exerts pressure on the free surface in said determined pressing direction, the pressure increasing auto-adaptively with an altitude of the free surface that increases in a direction opposite the determined pressing direction, and wherein the at least one pressing actuator or each pressing actuator is a resilient compression member; wherein the resilient compression member or each resilient compression member includes: a body having a bottom, and a piston movable inside the body in the determined pressing direction relative to the bottom, and wherein a sealed chamber including a pressurized gas is delimited between the bottom and the piston; and wherein the trolley, for the at least one pressing actuator or each pressing actuator includes: an inner cavity in which the at least one pressing actuator is housed, or a plurality of inner cavities where each pressing actuator is housed in one inner cavity of the plurality of cavities, or an inner cavity in which each pressing actuator is housed, and a rotational guide bearing for each piston.

2. The assembly according to claim 1, wherein the resilient compression member has a compression axis that extends in a direction common with the determined pressing direction.

3. The assembly according to claim 1, wherein a lower bottom delimits the inner cavity or wherein a respective lower bottom delimits each inner cavity of the plurality of cavities, in the determined pressing direction and limits travel of the at least one pressing roller or each pressing roller in the determined pressing direction.

4. The assembly according the claim 1, wherein the manufacturing assembly comprises a hemming unit, arranged to hem the two edges of the metal part to one another.

5. The assembly according the claim 1, wherein the pressure increases directly in response to the altitude of the free surface increasing in the direction opposite the determined pressing direction.

6. The assembly according the claim 1, wherein the pressure increases passively in response to the altitude of the free surface increasing in the direction opposite the determined pressing direction.

7. A manufacturing assembly for manufacturing a metal part, the manufacturing assembly comprising: a chassis provided with a station that receives the metal part; a flattening module that includes a trolley, and the flattening module including at least one pressing roller connected to the trolley, the metal part having two edges hemmed to one another, the two edges hemmed to one another defining a hemming line having a free surface; a longitudinal drive arranged to move the flattening module relative to the chassis along the hemming line when the metal part is at the station; and the flattening module including at least one pressing actuator that is arranged to move the at least one pressing roller in a determined pressing direction relative to the trolley and to place the at least one pressing roller to bear against the free surface such that the at least one pressing roller exerts pressure on the free surface in said determined pressing direction, the pressure increasing auto-adaptively with an altitude of the free surface that increases in a direction opposite the determined pressing direction; wherein the at least one pressing actuator or each pressing actuator is a resilient compression member having a compression axis that extends in a direction common with the determined pressing direction; wherein the resilient compression member or each resilient compression member includes: a body having a bottom, and a piston movable inside the body in the determined pressing direction relative to the bottom; and wherein a sealed chamber including a pressurized gas is delimited between the bottom and the piston; wherein the trolley, for the at least one pressing actuator or each pressing actuator includes: an inner cavity in which the at least one pressing actuator is housed, or a plurality of inner cavities where each pressing actuator is housed in one inner cavity of the plurality of cavities, or an inner cavity in which each pressing actuator is housed, and a rotational guide bearing for each piston; wherein a lower bottom delimits the inner cavity in the determined pressing direction and limits travel of the at least one pressing roller in the determined pressing direction, or wherein a respective lower bottom delimits each inner cavity of the plurality of cavities in the determined pressing direction and limits travel of each pressing roller in the determined pressing direction; and wherein the two edges hemmed to one another have a distal end part that is folded against a body of the metal part along the hemming line, and wherein the hemming line includes at least a first section having a first thickness and a second section having a second thickness greater than the first thickness, and wherein the flattening module is configured to flatten the first and second sections by: prior to the at least one pressing roller or each pressing roller being in contact with the hemming line, the at least one pressing actuator or each pressing actuator is configured to apply a predetermined pressure to the at least one pressing roller or each pressing roller such that the rotational guide bearing or each rotational guide bearing abuts against the lower bottom of the inner cavity or each inner cavity to determine an initial altitude of the at least one pressing roller or each pressing roller in the determined pressing direction taken relative to a reference surface, and when the at least one pressing roller or each pressing roller bears against a first section of the free surface, located at a first altitude greater than the initial altitude, the at least one pressing roller or each pressing roller is moved relative to the trolley in the direction opposite the determined pressing direction such that pressure exerted by the at least one pressing actuator or each pressing actuator on the at least one pressing roller or each pressing roller auto-adaptively increases to a first pressure, greater than the predetermined pressure, as a result of gas located in the sealed chamber or each sealed chamber being compressed due to the movement of the piston or each piston.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other features and advantages of the invention will emerge from the detailed description thereof provided below, for information and non-limitingly, in reference to the appended figures, in which:

(2) FIG. 1 is an illustration of a manufacturing assembly for a metal part not according to the invention;

(3) FIG. 2 is a view of the metal part obtained using the manufacturing assembly of FIG. 1, mounted around a mandrel;

(4) FIG. 3 is a schematic sectional illustration of the hemming line of the part of FIG. 2;

(5) FIG. 4 is a view similar to that of FIG. 2, for a metal part including a primary metal sheet and a partial metal sheet;

(6) FIG. 5 is a schematic sectional illustration of the hemming line of the part of FIG. 4, considered in a section where the primary metal sheet and the partial metal sheet are superimposed;

(7) FIGS. 6 and 7 are sectional views showing the actual state of the hemming line obtained when the manufacturing assembly of FIG. 1 is used for a part of the type shown in FIG. 4;

(8) FIG. 8 is a side view of a flattening module of a manufacturing assembly according to the invention;

(9) FIG. 9 is a front view of the flattening module of FIG. 8;

(10) FIG. 10 is a perspective view of the flattening module of FIGS. 8 and 9, the trolley being shown transparent;

(11) FIG. 11 schematically shows the operation of the flattening module of FIGS. 8 to 10, for a metal part of the type shown in FIG. 4; and

(12) FIGS. 12 and 13 are views similar to those of FIGS. 6 and 7, illustrating the actual state of the hemming line obtained when a part is formed of the type of that of FIG. 4 with a manufacturing assembly according to FIGS. 8 to 10.

(13) FIG. 14 schematically shows an example of a hemming unit.

(14) FIG. 15 schematically shows an alternative configuration of the manufacturing assembly.

DETAILED DESCRIPTION

(15) A manufacturing assembly 33 shown in FIGS. 8 to 11 is provided to manufacture a metal part 35 (FIG. 11), typically a metal part of an exhaust line of a vehicle with a heat engine. This vehicle is typically a motor vehicle, for example a car or truck.

(16) The metal part 35 has two edges hemmed to one another, the two edges hemmed to one another defining a hemming line 37 having a free surface 39.

(17) The metal part 35 typically forms a hollow body 40, inwardly delimiting a volume traveled by the exhaust gases.

(18) The metal part 35 is typically formed by a metal blank rolled around a central axis. The metal blank defines the two edges hemmed to one another. In this case, the edges are straight and parallel to one another.

(19) Alternatively, the metal part 35 is not rolled, but is for example formed by at least two shell parts, each shell part defining one of the two edges. For example, the metal part 35 is formed by two half-shells. The two half-shells in this case are hemmed to one another via their respective edges. In this case, each edge typically has a closed contour.

(20) According to another alternative, the metal part 35 could be formed from a plurality of shell parts.

(21) The manufacturing assembly 33 comprises a chassis 41 provided with a station 43 for receiving the metal part 35 (FIG. 11).

(22) In the case where the metal part 35 is of the rolled type, the receiving station 43 includes a mandrel 45 around which the metal part 35 is slipped.

(23) The mandrel 45 is a cylindrical part, having a central axis X. It has a section corresponding to the section of the metal part 35, for example circular or triangular.

(24) In this case, the metal part 35 is pressed against the outer surface of the mandrel 45.

(25) The hemming line 37 is typically straight and extends parallel to the central axis X. The free surface 39 of the hemming line 37 is turned away from the mandrel 45.

(26) Typically, the metal part 35 is obtained by rolling a metal stream around the mandrel 45, as described above.

(27) Typically, the manufacturing assembly 33 includes a lock (not shown) to hold the part in position at the receiving station. The lock, for example, can include clamps, or gripping rings, or any other appropriate member.

(28) The manufacturing assembly 33 further includes a flattening module 47, shown in detail in FIGS. 8 to 10.

(29) The flattening module 47 is provided to flatten the hemming line 37. It therefore performs the same function as the flattening module 20 of the manufacturing assembly 1 of FIG. 1.

(30) In other words, it makes it possible to completely fold down the two edges hemmed to one another against the body of the metal part, and to flatten the different thicknesses making up the hemming line so as to guarantee satisfactory tightness with respect to the exhaust gases along the hemming line.

(31) The flattening module 47 includes a trolley 48, and at least one pressing roller 49 connected to the trolley 48.

(32) The manufacturing assembly 33 includes a longitudinal drive 51 (FIG. 11) arranged to move the flattening module 47 relative to the chassis 41 along the hemming line 37 when the metal part 35 is loaded in the receiving station 43.

(33) In the illustrated example, the flattening module 47 includes two rollers 49, mounted one behind the other in the movement direction of the flattening module 47 along the hemming line 37. Alternatively, the flattening module 47 includes a single roller, or more than two rollers, for example three rollers.

(34) According to the invention, the flattening module 47 includes at least one pressing actuator 53, arranged to move the at least one pressing roller 49 in a determined pressing direction relative to the trolley 48 and to place it bearing against the free surface 39 such that the at least one pressing roller 49 exerts pressure on the free surface 39 in said determined pressing direction, the pressure increasing auto-adaptively with an altitude of the free surface 39 in a direction opposite the pressing direction.

(35) The pressing direction is shown by arrow P in FIGS. 9 and 11.

(36) Typically, each pressing roller 49 is connected to the trolley 48 by a dedicated pressing actuator 53.

(37) The longitudinal drive 51 is of any suitable type. It, for example, includes a rail 57 extending parallel to the hemming line 37, the trolley 48 being mounted sliding along the rail 57. The longitudinal drive 51 also includes a motor 59 that drives the trolley 48 along the rail 57 via a chain or any other appropriate member.

(38) The pressing actuator 53 is typically a resilient compression member, having a compression axis combined with the pressing direction.

(39) Advantageously, the resilient compression member is a gas cylinder.

(40) In this case, the gas cylinder includes a body 61 having a bottom 63, and a piston 65 connected to the corresponding pressing roller 49. The piston 65 is movable inside the body 61 in the pressing direction. A tight chamber containing a pressurized gas is delimited between the bottom 63 and the piston 65.

(41) When the piston 65 approaches the bottom 63, the gas contained in the chamber is compressed, and the pressure exerted by the resilient member on the pressing roller 49 in the pressing direction increases. Conversely, when the piston 65 moves away from the bottom 63, the gas pressure decreases in the chamber, and the pressure exerted by the resilient member on the pressing roller 49 decreases.

(42) The flattening module 47 includes, for the or each pressing roller 49, a bearing 67, secured to the piston 65. The roller 49 is rigidly fastened to a shaft 69, which is guided in rotation by the bearing 67.

(43) Typically, the trolley 48 comprises, for the or each pressing actuator 53, an inner cavity 71 in which said pressing actuator 53 and the bearing 67 are received. The pressing actuator 53 is rigidly fastened to the trolley 48, inside the inner cavity 71. The bearing 67 moves with the piston 65 inside the inner cavity 71. Bearing and piston travel in the pressing direction is limited by the lower bottom 73 of the inner cavity 71.

(44) Typically, the trolley 48 includes an inner cavity 71 for each pressing actuator 53. Alternatively, as schematically shown in FIG. 15, several pressing actuators 53 are housed in the same inner cavity 71.

(45) The shaft 69 extends in a direction perpendicular to the pressing direction. The shaft 69 passes all the way through the trolley 48.

(46) Alternatively, the resilient compression member is not a gas cylinder, but is a compression spring, for example a helical spring, or a slab of an elastomeric material or any other appropriate resilient member.

(47) Advantageously, the manufacturing assembly 1 comprises a hemming unit, arranged to hem the two edges of the part to one another and forming the hemming line 37.

(48) Typically, the hemming unit, for example, includes one or several sets of rollers 11, 18, 19 of the type described relative to FIG. 1.

(49) Advantageously, the trolley 48 is rigidly fastened to a moving chassis bearing the hemming unit. In this case, the longitudinal drive 51 is arranged to move the moving chassis along the hemming line 37.

(50) Alternatively, the longitudinal drive 51 moves the flattening module 47 independently of the unit having served to produce the hemming line.

(51) It is therefore understood that it is particularly advantageous to use the assembly 33 described above to manufacture a part whereof the hemming line 37 has a first section T1 along which the altitude of the free surface 39 is relatively less high, and a second section T2 along which the altitude of the free surface 39 is relatively higher.

(52) This part is, for example, the part described above in reference to FIG. 4. This part comprises a primary metal sheet 25 and a secondary metal sheet 27 pressed on the primary metal sheet 25 and covering only part of the primary metal sheet 25.

(53) At least one of the two edges has at least one thin segment 31 along which the primary metal sheet 25 is not covered by the secondary metal sheet 27. This edge also has at least one thick segment 29 along which the primary metal sheet 25 is covered by the secondary metal sheet 27.

(54) For example, each edge has two thin segments 31, arranged on either side of the thick segment 29.

(55) Along the hemming line 37, each thin segment 31 of one of the two edges is hemmed with a thin segment 31 of the other edge. Each thick segment 29 of one of the edges is hemmed with a thick segment 29 of the other edge.

(56) The thick segments 29 form the second section T2.

(57) The thin segments 31 form the first section T1. They, for example, also form a third section T3 along which the altitude of the free surface 39 is substantially the same as along the first section T1. The sections T1 and T3 are located on either side of the second section T2 of the hemming line 37.

(58) FIG. 11 illustrates why the pressing actuator 53 makes it possible to increase the pressure exerted by the pressing roller 49 on the free surface 39, auto-adaptively with the altitude of the free surface 39 in a direction opposite the pressing direction, for such a part.

(59) In FIG. 11, the movement direction of the flattening module 47 is embodied by the arrow D. The altitude of the free surface 39 in the direction opposite the pressing direction may be taken relative to any reference surface. For example, it may be taken relative to the outer surface of the mandrel.

(60) Before the pressing roller 49 is in contact with the hemming line 37, the pressing actuator 53 applies a predetermined pressure P0 to the pressing roller 49.

(61) Under the effect of this pressure, the bearing 67 abuts against the lower bottom 73 of the inner cavity 71. This determines the position of the pressing roller 49 in the pressing direction. This situation is illustrated in the left part of FIG. 11.

(62) When the pressing roller 49 bears against the first section T1 of the free surface 39, located at an altitude H1, the pressing roller 49 is moved relative to the trolley 48 in a direction opposite the pressing direction P. The pressure exerted by the pressing actuator 53 on the pressing roller 49 in the pressing direction P increases to a pressure P1, greater than the pressure P0.

(63) This is obtained auto-adaptively, and results from the fact that the gas located in the sealed chamber of the pressing actuator is compressed due to the movement of the piston 65. The pressure increase occurs passively, without any automatism, or sophisticated steering member.

(64) This situation is shown in the middle on the left in FIG. 11.

(65) When the pressing roller 49 moves in contact with the second section T2 of the free surface 39, located at an altitude H2 greater than the altitude H1, the pressing roller 49 is offset in a direction opposite the pressing direction relative to the first section T1. The pressure exerted by the pressing actuator 53 on the pressing roller 49 therefore increases to a pressure P2 greater than the pressure P1.

(66) This results from the movement of the piston 65 toward the bottom 63, which increases the gas pressure in the tight chamber. This increase in the pressure exerted on the pressing roller 49, and therefore the pressure exerted by the pressing roller 49 on the free surface 39 of the hemming line 37, is auto-adaptive.

(67) This situation is shown in the middle on the right in FIG. 11.

(68) When the pressing roller 49 arrives at the third section T3, located at the first altitude H1, the pressure exerted by the pressing actuator 53 on the pressing roller 49 in the pressing direction automatically returns to the value P1.

(69) This situation is illustrated in the right part of FIG. 11.

(70) FIGS. 12 and 13 show the results obtained for such a part, when the manufacturing assembly 33 according to the invention is used for the hemming of the part.

(71) FIG. 13 shows, in sectional view in a plane perpendicular to the movement direction, how the second section T2 is formed. One can see that the hemming line 37 is well-formed, the different thicknesses making up the two edges being in close contact with one another.

(72) FIG. 12 is a sectional view taken along the first section T1. One can see that the quality of the hemming is much better than that obtained in FIG. 6.

(73) In FIGS. 6 and 7, the hemming line L had been flattened with a manufacturing assembly shimmed to exert a predetermined force in the pressing direction on a free surface situated at a height H2. Along the second section, the hemming line is well-formed. Conversely, the pressure exerted on the first section of the hemming line L is too weak, since this first section is situated at a height H1 lower than the height H2. As a result, in the device of FIG. 1, due to the absence of a pressing actuator, it is not possible to obtain a good quality hemming line.

(74) With the manufacturing assembly 33 according to the invention, it is possible to obtain a part forming a hollow volume of an exhaust line, the hemming line 37 after flattening having a leak rate of less than 30 l/min, preferably less than 15 l/min, and still more preferably less than 10 l/min.

(75) This leak rate is measured under standard conditions.

(76) The manufacturing assembly 33 may have multiple alternatives.

(77) According to one alternative embodiment, it is designed to process a metal part that is already hemmed. In this case, the manufacturing assembly does not include the hemming unit. Alternatively, it includes both the pressing module and the hemming unit.

(78) According to one alternative embodiment, each pressing roller is mounted rotating around a stationary shaft. This shaft is then rigidly fastened to the pressing actuator, using any appropriate means.

(79) The assembly is well suited to manufacturing a part whereof the hemming line has any type of shape. It is straight, or bowed in a plane, or follows a three-dimensional shape.

(80) The first and second sections of the hemming line do not necessarily follow a rising step, as described above. Alternatively, they follow a descending step. According to another alternative, each section has a variable height, rising uniformly or descending uniformly or alternately rising and descending. The considered height for each section is then the average height.

(81) The metal part does not necessarily include a primary metal sheet and a secondary metal sheet only partially covering the primary metal sheet. The thin and thick segments of the edges alternatively belong to zones with different thicknesses of the same metal sheet. According to another alternative, the thin and thick segments of the edges belong to different metal sheets juxtaposed alongside one another.

(82) Although an embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this disclosure. For that reason, the following claims should be studied to determine the true scope and content of this disclosure.