Force multiplier device and mold using the force multiplier

Abstract

Force multiplier device (1; 100) configured to be associated with molds (50) comprising: - a first and a second prismatic body (2, 3) configured to be associated with a mold (50) and arranged side by side to identify a longitudinal direction (Y) of mutual sliding; - a housing (4) comprising a seat (5) and a counter-seat (6) made respectively in the first and second prismatic body (2, 3), - a contrasting body (7) housed in the housing (4) and in contact with pushing means (8); when this contrasting body (7) is housed in the counter-seat (6), it generates a contrasting force (Fc) which opposes the mutual displacement of the prismatic bodies (2, 3) and whose value depends on: - the shape of the counter-seat (6) and of the contrasting body (7); - from the pushing force (S) with which the pushing means (8) force the contrasting body (3) inside the counter-seat (6).

Description

[0001] FORCE MULTIPLIER DEVICE AND MOLD USING THE FORCE MULTIPLIER

[0002] DESCRIPTION

[0003] The invention relates to a force multiplier device suitable for application to dies, such as dies for bending or deep drawing sheet metal.

[0004] The invention also relates to a die that uses the force multiplier device.

[0005] As is known, in sheet metal stamping processes, such as certain bending or drawing processes, it is necessary to have dies equipped with devices suitable for constraining the punch or die to the thrust member during stamping and releasing them when the desired deformation has been achieved.

[0006] To this end, the prior art provides for the use of fluid actuators, preferably hydraulic, that act on the die. Generally, according to the prior art, actuators that act directly on the moving parts of the dies are used.

[0007] Given the significant forces involved, it is necessary to use actuators that develop large forces, usually in the order of thousands of Newtons (kN).

[0008] However, these types of actuators have the disadvantage of being large, often larger than the dimensions of the molds to which they are applied.

[0009] This significantly increases the size of the tooling, understood as the mold-actuator assembly, and the primary drawback is the complication of handling the tooling and mounting it on the press.

[0010] Another drawback is the high cost of the actuators, which obviously increases significantly as their size increases.

[0011] The present invention aims to overcome the aforementioned drawbacks and, in particular, has as its primary objective the creation of a force multiplier device suitable for application to molds, especially bending or drawing molds, to limit the deformation force exerted by the punch or die, or both, during molding operations, replacing the large, state-of-the-art actuators currently used.

[0012] Another object of the invention is that the dimensions of the force multiplier device of the invention are significantly smaller than those of prior art actuators that achieve the same purposes and are applied to molds for the same uses.

[0013] It is a further object of the invention that the costs of manufacturing the force multiplier device of the invention are lower than those of equivalent prior art actuators. It is also a purpose of the invention to produce a mold that uses the force multiplier of the invention.

[0014] The objects listed here are achieved by the force multiplier of the invention and by the mold that uses it, also the subject of the invention, whose characteristics are described in claim 1 and the dependent claims.

[0015] Advantageously, the use of the force multiplier of the invention applied to a drawing or bending mold allows for the creation of a tool intended as a combination of mold and force multiplier, smaller in size than the same tool that according to the prior art comprises the mold and its respective actuator.

[0016] Consequently, the use of the force multiplier of the invention makes the molds to which it is applied easier to handle and less cumbersome than those of the prior art. An additional advantage of using the force multiplier according to the invention applied to a mold is that it allows for multi-level molding.

[0017] Furthermore, advantageously, the force multiplier device according to the invention allows for both top- down and bottom-up molding.

[0018] The purposes and advantages listed above will be described in more detail in the following description, which is provided for illustrative and non-limitative purposes with reference to the attached drawings in which:

[0019] - Figs. 1 and 2 represent an axonometric view and a front view, respectively, of the force multiplier 15 of the invention applied to a mold;

[0020] - Figs. 3 to 5 represent different cross-sections of Fig. 2;

[0021] - Figs. 6 to 10 represent details of Fig. 2;

[0022] - Figs. 11 to 15 show the force multiplier of the invention in different stages of sheet metal forming;

[0023] - Fig. 16 shows an axonometric view of a variant embodiment of the force multiplier of the invention applied to a die.

[0024] The force multiplier device of the invention is shown in Figures 1 to 15, where it is generally indicated by the numeral 1, and is applied to a die 50 that creates the deep drawing of a sheet of metal L.

[0025] However, in another application form, the force multiplier device 1 of the invention may also be applied to a die of another type, for example, one suitable for bending sheet metal.

[0026] Figures 1 and 2 show that, according to the invention, the force multiplier device 1 comprises a first prismatic body 2 and a second prismatic body 3, which are configured to be associated with the mold 50.

[0027] These first prismatic bodies 2 and second prismatic bodies 3 are arranged side by side at contact surfaces that comprise a first contact surface 2a belonging to the first prismatic body 2 and a second contact surface 3a belonging to the second prismatic body 3.

[0028] The aforementioned contact surfaces 2a, 3a identify a longitudinal direction Y of mutual sliding of the prismatic bodies 2, 3 along the contact surfaces, as will be described below.

[0029] Figures 6 to 10 show, in particular detail, the presence of a housing 4 comprising a seat 5 formed in the first prismatic body 2 and a counter-seat 6 formed in the second prismatic body 3, which face each other and communicate with each other.

[0030] Also noted is the presence of a counter-body 7, which slides into housing 4, as shown in Figures 1 and 2, and is in contact with thrust means 8 that control the movement of the counter-body 7 along housing 4 between seat 5 and counter-seat 6, and in a transverse direction X, shown in Figures 1 and 2, orthogonal to the prismatic bodies 2 and 3 and therefore to their contact surfaces 2a and 3a.

[0031] When the counterbody 7 is housed in the counterseat 6, it generates a counterforce Fc that opposes the mutual displacement of the prismatic bodies 2, 3 along said contact surfaces 2a, 3a, and whose value depends on:

[0032] - the shape of the counterseat 6;

[0033] - the shape of the counterbody 7; - by the thrust S with which the thrust means 8 force the counter-bearing body 7 into the counter-seat 6 in said transverse direction X.

[0034] The force multiplier device is configured such that as long as the aforementioned counter-bearing force Fc is greater than the forming force Fs indicated in Figures 1, 2, 11, and 12 acting on the die 50 and which the die 50 transfers to the prismatic bodies 2, 3 to deform the sheet metal L, the aforementioned counter-bearing force Fc rigidly constrains the prismatic bodies 2, 3, adhering to each other at the contact surfaces 2a, 3a.

[0035] Conversely, when the counter-bearing force Fc is less than the forming force Fs, the counter-bearing body 7 is translated towards the seat 5 and the reciprocal sliding of the prismatic bodies 2, 3 along the contact surfaces 2a, 3a is permitted.

[0036] In order for what has been described to occur, with reference to Figures 6 to 10, it is observed that the contrasting body 7 has the cylindrical external profile 7a which can be combined both with the concavity 5a of the seat 5, which essentially recalls the shape of the letter U, and also with the concavity 6a of the counter-seat 6, which essentially recalls the shape of the letter C.

[0037] It is observed in particular in Figure 9 that the open area 5b of the seat 5 belongs to the first contact surface 2a of the first prismatic body 2 and is delimited by a lower edge 5d and an upper edge 5c which protrudes with respect to the lower edge 5d with reference to a transverse direction X orthogonal to the first contact surface 2a.

[0038] It is also noted that the open region 6b of the counterseat 6 belongs to the second contact surface 3a of the second prismatic body 3 and is delimited by an upper edge 6c and a lower edge 6d that protrudes from the upper edge 6d with reference to the same transverse direction X orthogonal to the second contact surface 3a.

[0039] In particular, it is observed that the lower edge 6d is curved and has the convexity 6e facing outward from the aforementioned open region 6b. The convexity 6e is obtained by appropriately shaping the lower edge 6d through mechanical processing, which is performed directly on the second prismatic body 3, as shown in Figures 6, 7, 9, and 10, or through a shaped insert 11, shown in Figure 8, which is housed in a housing 12 created in the second prismatic body 3.

[0040] In this case, the advantage is that the curvature of the convexity 6e can be varied by appropriately varying the profile of the shaped insert 11, which can also be conveniently replaced when worn.

[0041] Finally, advantageously, the shaped insert 11 can also be made of hard metal, such as widia or equivalent materials.

[0042] By appropriately choosing the different profiles and dimensions of the contrast body 7, the seat 5, and the counter-seat 6, and the shapes of their upper edges 5c, 6c, and lower edges 5d, 6d, as well as the thrust F with which the thrust means 8 force the contrast body 7 into the counter-seat 6, the operator is able to create different constraint conditions that allow for different values of the contrast force Fc between the prismatic bodies 2, 3, depending on the desired forming force Fs.

[0043] As for the thrust means 8, they can be of any type, provided they are suitable for moving the counterpressure body 7 within the housing 4 and forcing it into the counter-pressure seat 6.

[0044] The thrust means 8 can therefore comprise at least one elastic assembly consisting of one or more springs or elastomers connected to the first prismatic body 2 and in operational contact with the counter-pressure body 7. Preferably, in the embodiment described here, the thrust means 8 are visible in Figures 1 and 2 and in detail in Figure 4, where they are connected to the first prismatic body 2 and comprise a fluid cylinder 9, preferably but not necessarily associated with two rods 10, each of which is housed through a sliding seat 11 formed in the first prismatic body 2 and which communicates with the housing 4, within which the end 10a of each rod 10 is in contact with the counter-pressure body 7.

[0045] Preferably, this Fluid cylinder 9 is a gas cylinder, specifically a nitrogen cylinder.

[0046] An embodiment of the force multiplier device of the invention, indicated overall by 100, is shown in Figure 16, where it is noted that it differs from the embodiment described only in that it comprises two first prismatic bodies 2, which are arranged on opposite sides of a single second prismatic body 3, located between them, where each of the two first prismatic bodies 2 is in contact with the single second prismatic body 3 at their respective contact surfaces 2a and 3a.

[0047] The invention also relates to a mold, indicated overall by 50 and visible overall in Figures 1 and 2 and 11 to 16, which comprises a lower mold block 51 configured to be placed on the bed of a press (not shown), and an upper mold block 52 configured to be applied to the crosshead of the same press (also not shown).

[0048] The mold 50 also includes a blank holder 53, which is positioned above the lower mold block 51 and is designed to support a sheet metal L to be molded, and a punch 54, supported by the lower mold block 51, which passes through the blank holder 52.

[0049] Furthermore, there is also a die 55 positioned above the blank holder 53 and configured to cooperate with the respective punch 54, which can be seen in particular in the cross-section of Figure 5.

[0050] According to the invention, the mold includes a force multiplier device 1; 100, which was previously described, is included between the lower mold block 51 and the upper mold block 52 and has each first prismatic body 2 fixed to the upper mold block 52 and the second prismatic body 3 which houses the die 55 and is associated with the upper mold block 52.

[0051] Furthermore, we also observe the presence of elastic means 56 arranged along the longitudinal direction Y and interposed between the prismatic bodies 2, 3 and the upper mold block 52 which make the movement of the prismatic bodies 2, 3 elastic during the molding of the sheet metal L.

[0052] In particular, it is observed that the elastic means 56 comprise a cylindrical body 57 belonging to the upper mold block 52 in which a piston 58 is slidably housed, provided with a rod 59 having the end 59a fixed to the second prismatic body 3 and between the piston 59 and the bottom 60 of the cylinder 57 is interposed with an elastic body 61.

[0053] Operationally, the operation of the force multiplier device 1 of the invention during the stamping of the sheet metal L is described with reference to Figures 11 to 15.

[0054] The stamping operation begins with the die 50 and the force multiplier device 1 arranged in the configuration shown in Figure 11, where it can be seen that the sheet metal L to be stamped is positioned on the blank holder 53 and is included between the punch 54 and the die 55.

[0055] Under these conditions, the prismatic blocks 2, 3 are constrained together because the thrust means 8 create the thrust S which forces the contrasting body 7 into the counter-seat 6, generating the contrasting force Fc which keeps them united.

[0056] When the stamping force Fs, as seen in Figure 12, is applied to the die 55, and if the thrust S of the thrust means 8 is such as to generate a counterforce Fc greater than the stamping force Fs, both prismatic blocks 2 and 3 lower in the direction of the stamping force Fs, the punch 54 enters the die 55, and the sheet metal L, as seen in Figure 12, is stamped. Essentially, in the force multiplier device 1 of the invention, the counterforce Fc is generated by the interference that the counterbody 7 generates within the counterseat 6 when forced by the thrust S of the fluid cylinder 9.

[0057] Tests carried out on prototypes have shown that by appropriately shaping the counterbody 7 and its respective counterseat 6 and using thrust means 8 with fluid cylinders 9 that generate a thrust S of the order of a hundred Newtons (N), it is possible to generate counterforces Fc. capable of withstanding molding forces Fs of the order of a thousand Newtons (N) and therefore with a force ratio of the order of magnitude 1:10.

[0058] After molding, if the molding force Fs increases beyond the value of the counterforce Fc, the rods 10 of the fluid cylinder 9 begin to retract and the counterbody 7 begins to exit the counterseat 6, allowing the first prismatic body 2 to lower with respect to the second prismatic body 3, as shown in Figures 25, 13, and 14.

[0059] The lowering of the first prismatic body 2 ends when the counterbody 7 has completely retracted into the seat 5, as shown in Figure 15.

[0060] At the end of molding, the elastic means 56, which were compressed during the lowering of the prismatic bodies 2 and 3, restore the accumulated elastic thrust and facilitate the return of the mold 50 and the force multiplier device 1 to the initial condition shown in Figure 11.

[0061] Obviously, what has been described can be repeated for the executive variant of the force multiplier device 100, the only difference being that the presence of two first prismatic bodies 2 and their respective counteracting bodies 7 essentially doubles the counterforce Fc that opposes the molding force Fs.

[0062] Furthermore, it should be emphasized that the force multiplier device described can also be used in other fields of the art, similar or different from molding, where the characteristics of this device are required.

[0063] Based on what has been said, it is clear that the force multiplier device of the invention, in both embodiments described, achieves the intended purposes.

[0064] In particular, it has been seen that the force multiplier device of the invention replaces equivalent prior art actuators, allowing for a significant reduction in the volume of the equipment intended as a mold-actuator assembly.

[0065] In this way, compared to prior art, the use of the force multiplier device of the invention also simplifies the assembly and handling of the equipment.

[0066] Finally, costs are also reduced since, as mentioned, the force multiplier of the invention uses smaller and therefore less expensive actuators than the actuators used in the prior art.

[0067] During the execution phase, variations and modifications may be made to the device and mold of the invention that are not cited in this description or shown in the attached drawings.

[0068] If these variations and modifications fall within the scope of the claims appended hereto, they shall be considered protected by this patent document.

Claims

CLAIMS1) Force multiplier device (1; 100) configured to be associated with die (50), preferably for deep drawing and / or bending of metal sheets (L), characterized by comprising:- at least a first prismatic body (2) and a second prismatic body (3) configured to be associated with a die (50), said first prismatic body (2) and said second prismatic body (3) being arranged side by side at contact surfaces comprising a first contact surface (2a) belonging to said at least one first prismatic body (2) and a second contact surface (3a) belonging to said second prismatic body (3) that define a longitudinal direction (Y) for the mutual sliding of said prismatic bodies (2, 3) along said contact surfaces;- a housing (4) comprising a seat (5) made in said at least one first prismatic body (2) and a counter-seat (6) made in said second prismatic body (3) and facing and communicating with said seat (5);- a counteracting body (7) housed in said housing (4) and in contact with pushing means (8) that control the movement of said counteracting body (7) along said housing (4) between said seat (5) and said- counter-seat (6); when said counteracting body (7) is housed in said counter-seat (6), it generates a counteracting force (Fc) that opposes the mutual movement of said prismatic bodies (2, 3) along said contact surfaces (2a, 3a), the value of which depends on:- the shape of said counter-seat (6);- the shape of said counteracting body (7);-the pushing force (S) with which said pushing means (8) force said counteracting body (7) inside said counter-seat (6) in a transverse direction (X) orthogonal to said longitudinal direction (Y).2) Force multiplier device (1; 100) according to claim 1, characterized by being configured such that:-as long as said counteracting force (Fc) is greater than the stamping force (Fs) acting on said die (50) and which said die (50) transfers to said prismatic bodies (2, 3) to deform the metal sheet (L), said counteracting force (Fc) rigidly constrains said prismatic bodies (2, 3);- when said counteracting force (Fc) is less than the stamping force (Fs) acting on said mold (50) and which said die (50) transfers to said prismatic bodies (2, 3), said counteracting body (7) is moved towards said seat (5), allowing the mutual sliding of said prismatic bodies (2, 3).3) Force multiplier device (1; 100) according to any of the preceding claims, characterized in that said pushing means (8) comprise an elastic group connected to said at least one first prismatic body (2) and operatively in contact with said counteracting body (7).4) Force multiplier device (1; 100) according to any of the preceding claims 1 or 2, characterized in that said pushing means (8) comprise a fluid cylinder (9) connected to said at least one first prismatic body (2) and to which one or more rods (10) are associated, each housed passing through a sliding seat (11) made in said at least one first prismatic body (2) and communicating with said housing (4), inside which the end (10a) of said rod (10) is in contact with said counteracting body (7).5) Force multiplier device (1; 100) according to claim 4, characterized in that said fluid cylinder (9) is associated with two rods (10) parallel to each other.6) Force multiplier device (1; 100) according to any of the preceding claims, characterized in that said counteracting body (7) has an external cylindrical profile (7a) that can be conjugated to the concavity (5a) of said seat (5) which substantially recalls the shape of the letter U and to the concavity (6a) of said counterseat (6) which substantially recalls the shape of the letter C, the open area (5b) of said seat (5)belonging to said first contact surface (2a) of said at least one first prismatic body (2) and the open area (6b) of said counter-seat (6) belonging to said second contact surface (3a) of said second prismatic body (3).7) Force multiplier device (1; 100) according to claim 6, characterized in that:-said open area (5b) of said seat (5) is delimited by a lower edge (5d) and by an upper edge (5c) which projects relative to said lower 10 edge (5d) with reference to a transverse direction (X) orthogonal to said first contact surface (2a);-said open area (6b) of said counter-seat (6) is delimited by an upper edge (6c) and by a lower edge (6d) which projects relative to said upper edge (6c) with reference to a transverse direction (X) orthogonal to said second contact surface (3a).

8. Force multiplier device (1; 100) according to claim 7, characterized in that said lower edge (6d) that delimits said open area (6b) of said counter-seat (6) is curved and presents an outwardfacing convexity (6e) of said open area (6b) of said counter-seat (6) which it delimits.9) Force multiplier device (1; 100) according to claim 8, characterized in that said curved lower edge (6d) is obtained by a shaped insert (11) housed in a housing (12) made in said second prismatic body (3).10) Force multiplier device (1; 100) according to any of the preceding claims, characterized in that it comprises a single first prismatic body (2) adjacent to a single second prismatic body (3) which are arranged in mutual contact at said respective contact surfaces (2a, 3a).11) Force multiplier device (100) according to any of the preceding claims from 1 to 9, characterized in that it comprises two first prismatic bodies (2) arranged on opposite sides of a single second prismatic body (3) interposed between them, wherein each of said two first prismatic bodies (2) is in contact with said single second prismatic body (3) at said respective contact surfaces (2a, 3a).12) Die (50) comprising:- a lower die block (51) configured to be placed on the press table;- an upper die block (52) configured to be applied to the crossbar of said press;- a blank holder (53) placed above said lower die block (51) and designed to receive a sheet (L) to be stamped;-at least one punch (54) supported by said lower die block (51) and arranged passing through said blank holder (53);-at least one die (55) positioned above said blank holder (53) and configured to cooperate with a respective punch (54), characterized by comprising a force multiplier device (1; 100) according to any of the claims from 1 to 11, which is included between said lower die block (51) and said upper die block (52) and which features:- said at least one first prismatic body (2) that is fixed to said upper die block (52);- said second prismatic body (3) that supports said at least one die (55) and is associated with said upper die block (52);- elastic means (56) interposed between said prismatic bodies (2, 3) and said upper die block (52) and arranged along said longitudinal direction (Y).13) Die (50) according to claim 12, characterized in that said elastic means (56) comprise a cylindrical body (57) belonging to said upper die block (52) in which a piston (58) provided with a rod (59) having an end(59a) fixed to said second prismatic body (3) is slidably housed, between said piston (58) and the bottom (60) of said cylinder(57) being interposed an elastic body (61).

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