Workpiece treatment apparatus

Abstract

A workpiece treatment apparatus, which comprises at least one frame (2) for supporting two clamping assemblies (3a, 3b), which are provided with the capacity for relative translation along a main direction (A) of mutual approach and spacing apart; the assemblies (3a, 3b) comprise respective electrodes (4) which face each other and are configured for clamping a pair of workpieces to be permanently bonded; at least one first assembly (3a) comprises a compensation device (9); such device (9) comprises a plurality of presser elements (10) which are adapted to exert, in at least one active configuration, a direct or indirect pressure on the respective electrode (4) which is directed toward the other electrode (4). Each element (10) comprises a plunger (11) which can move parallel to the main direction (A) and which is partially accommodated so that it can slide within a respective chamber (12), which has a first compartment (13a) and a second compartment (13b) which are separated by such plunger (11). At least the first compartments (13a), i.e. the compartments arranged on the opposite side from the corresponding electrode (4), are placed in mutual communication by means of a compensation circuit (14), which during use is kept closed and filled with a pressurized fluid, which in turn is adapted to keep the presser elements (10) in the active configuration.

Description

[0001] WORKPIECE TREATMENT APPARATUS

[0002] The present invention relates to a workpiece treatment apparatus, designed in particular for the permanent mutual bonding of semi-finished products and workpieces in general by means of treatments such as, for example, those of the type known as “diffusion bonding” or welded bonds (resistance welding or other types of welding). The possibility is not ruled out however of using the apparatus for other types of treatments.

[0003] The term “diffusion bonding” identifies a specific technique for permanently bonding two workpieces, which can be made of identical or different materials. It is based on the physical phenomenon whereby two (metallic) surfaces pressed against each other tend to exchange atoms over time, until they form a strong, stable bond.

[0004] To carry out this technique, it is necessary to bring the two workpieces of interest to high temperatures (but lower than melting temperatures) and apply high pressures to them: by doing this it is possible to obtain a permanent bond without needing to resort to any melting, and possibly without requiring the addition of other material.

[0005] In detail, execution of a “diffusion bonding” process entails clamping the two workpieces between two elements or apparatuses, at least one of which can be moved with respect to the other along a common direction of movement toward and / or away from each other, in such a way that the surfaces designated for bonding are pressed against each other. Subsequently, the workpieces are brought to the desired temperature, by virtue of current passed through the elements, and then an intense pressure is applied for the time needed to obtain the permanent bond (several hours may be necessary), by virtue of the exchange of atoms between the surfaces pressed together, which are destined to form the joining area.

[0006] Owing to the manner in which the bond is obtained, the technique described above is in fact not a welding technique per se (although it is sometimes described as "welding by atomic diffusion"); in any case, the technique makes it possible to obtain results comparable to or even better than those achievable with welding and it is used, for example, for the permanent bonding of components used in the distribution of power in the automotive sector and the like.

[0007] This technique presents some drawbacks, however.

[0008] To ensure uniform joining, as required by the rigors of the market, the workpieces to be bonded must be in perfect mutual contact for the entire extent of the surfaces that will form the joining area.

[0009] In this context, any irregularity in the flatness of the workpieces, or even in the components involved in the process, will compromise the successful outcome of that process, and this translates to the necessity for flatness of great precision, which to date has restricted the applicability of the process to small components, with dimensions of the surfaces involved that are mutually similar (both in length and in width). Only under these conditions in fact has it been possible up to now to ensure the necessary uniformity of the pressure applied, without which of course it is not possible to obtain a bond that is in turn uniform and high-quality.

[0010] Furthermore, it is in the very nature of the process for thermal deformations to be introduced when a workpiece becomes hotter, so resulting in further irregularities in the result obtained.

[0011] The aim of the present invention is to solve the abovementioned problems, by providing an apparatus that makes it possible to obtain the permanent bonding of workpieces of any shape and size, while still ensuring high quality and consistency of the result obtained.

[0012] Within this aim, an object of the invention is to provide an apparatus that makes it possible to execute "diffusion bonding" treatments or in any case to carry out permanent bonds on workpieces of large dimensions, while ensuring high quality and consistency of the result obtained.

[0013] Another object of the invention is to provide an apparatus that is capable of ensuring high quality and consistency even in the presence of irregularities in the flatness of the workpieces or of the components of the apparatus itself.

[0014] Another object of the invention is to provide an apparatus that can operate effectively, even on workpieces of large dimensions, with reduced energy consumption.

[0015] Another object of the invention is to provide an apparatus that is capable of rendering the pressure exerted on the surfaces in mutual contact uniform and constant.

[0016] Another object of the invention is to provide an apparatus that ensures a high reliability of operation.

[0017] Another object of the invention is to provide an apparatus that adopts an alternative technical and structural architecture to those of conventional apparatuses.

[0018] Another object of the invention is to provide an apparatus that can be easily implemented using elements and materials that are readily available on the market.

[0019] Another object of the invention is to provide an apparatus that is low cost and safely applied.

[0020] This aim and these and other objects which will become more apparent hereinafter are achieved by an apparatus according to claim 1.

[0021] Further characteristics and advantages of the invention will become more apparent from the description of a preferred, but not exclusive, embodiment of the apparatus according to the invention, which is illustrated by way of non-limiting example in the accompanying drawings wherein:

[0022] Figures 1 and 2 are perspective views of the apparatus according to the invention, seen from the front and from the rear;

[0023] Figure 3 is a view from above of the apparatus in the previous figures;

[0024] Figure 4 is a cross-sectional view of Figure 3, taken along the line IV-

[0025] IV;

[0026] Figure 5 is a greatly enlarged detail of Figure 4; Figure 6 is a perspective view of the compensation device of the apparatus in the previous figures;

[0027] Figure 7 is a view from above of the device of Figure 6;

[0028] Figure 8 is a cross-sectional view of Figure 7, taken along the line VIII- VIII;

[0029] Figure 9 is a cross-sectional view of Figure 7, taken along the line IX- IX.

[0030] With particular reference to the figures, the reference numeral 1 generally designates a workpiece treatment apparatus, for workpieces of any type and preferably, but not necessarily, made of metal.

[0031] In particular, the apparatus 1 can be used to permanently bond two (or more) semi-finished products or other workpieces by means of a "diffusion bonding" treatment (or, in other words, by means of welding by atomic diffusion). In this context, for example the workpieces could be components intended for the distribution of power, for use in the automotive sector or the like.

[0032] While remaining within the scope of protection claimed herein, the apparatus 1 can in any case be effectively used to permanently bond any kind of workpiece, by means of "diffusion bonding" or by means of welding processes of various other kinds (resistance welding for example), or even to carry out other treatments, where the person skilled in the art deems it possible or profitable to avail of the features illustrated below.

[0033] The process of "diffusion bonding" (which identifies the area of preferred, but not exclusive, application of the invention) is well-known in the background art and, quite apart from what is discussed below, the apparatus 1 can be used to execute it according to conventional methods, which are well-known to the person skilled in the art. According to these conventional methods, the apparatus 1 can therefore be configured to permanently bond two (or more) workpieces by means of atomic exchange between surfaces placed in contact (pressed together and subjected to conditions of controlled temperature). The welding processes and other treatments optionally imparted by the apparatus 1 can also be executed according to conventional methods, in addition to the features that will be explained below.

[0034] The apparatus 1 comprises, first of all, at least one frame 2 for supporting two clamping assemblies 3a, 3b, which are provided with the capacity for relative translation along a main direction of mutual approach and spacing apart. In particular, the main direction A is preferably vertical (as in the accompanying figures), but it could also be oriented differently, while remaining within the scope of protection claimed herein.

[0035] Along the main direction A, in a first option, which corresponds to the accompanying figures, only one of the assemblies 3a, 3b can be moved (for example the upper one indicated with 3b in the figures), and can thus be moved closer to or away from the other. In a different option, which is also comprised in the invention, both assemblies 3a, 3b can be moved.

[0036] The term "relative translation" means that the motion concerns at least one of the two assemblies 3a, 3b with respect to the other.

[0037] The assemblies 3a, 3b comprise respective electrodes 4 which face each other and are configured for clamping a pair of workpieces to be permanently bonded.

[0038] According to methods that are traditional per se, the workpieces to be permanently bonded are placed between the electrodes 4 so that, by moving the assemblies 3a, 3b closer together, the electrodes 4 can exert sufficient pressure on those workpieces (which are brought to the desired temperature) and enable the joining at the surfaces in mutual contact, by means of welding, diffusion bonding or the like.

[0039] In particular, in the case of "diffusion bonding" the clamping action develops a force that, with the temperature of the workpieces having been raised in the meantime, is capable of generating a pressure on the mentioned surfaces which is sufficient to trigger the phenomenon of atomic exchange. The frame 2 can be conventional and, as in the accompanying figures, can for example comprise a cabinet 5 that offers accommodation and / or support for the components necessary to the correct operation of the apparatus 1, including for example the motor 6a that actuates the movement means 6b, which is responsible for making one or both of the assemblies 3a, 3b translate along the main direction A.

[0040] Furthermore, the apparatus 1 can be provided with a control and command station 7, independent of the cabinet 5 (as in the accompanying figures) or integrated in it.

[0041] It is emphasized however that, for all aspects not discussed in the present description, any implementation detail relating to the apparatus 1 can be conventional. In particular therefore, the apparatus 1 can be provided with all the components necessary or useful to the operation that the person skilled in the art will be able to identify based on the common general knowledge of the sector and according to the specific requirements, while remaining within the scope of protection claimed herein.

[0042] With regard to the components necessary to the correct operation, it should be noted at this point that in the solution in the accompanying figures the electrodes 4 are brought to the desired temperature by plates 8 (made of copper) passed through by a current, which is applied to the electrodes 4 on the opposite side from the mutually facing portions thereof.

[0043] According to the invention, at least one first assembly 3a comprises a compensating device 9, in particular for compensating the irregularities in the flatness of the workpieces and / or of the assemblies 3 a, 3b and / or of other components of the apparatus 1 which are involved in the treatment. It should be noted in this regard that the distinction between "first" assembly 3a and "second" assembly 3b is used here solely to distinguish the assembly (3a) that is fitted with the device 9 from the assembly (3b) that is not. In the accompanying figures, the first assembly 3a is the lower one, but it could also be the upper one; however, the possibility is not ruled out of both assemblies 3 a, 3b being fitted with a respective device 9.

[0044] The device 9 comprises a plurality of presser elements 10 which are adapted to exert, in at least one active configuration, a direct or indirect pressure on the respective electrode 4 (i.e. belonging to the same assembly 3a) which is directed toward the other electrode 4 (the one belonging to the other assembly 3b). "Indirect" pressure means that other components may be interposed between the element 10 and the electrode 4 (such components are absent in the case of "direct" pressure, which in any case is comprised in the scope of protection claimed herein).

[0045] Each presser element 10 comprises a plunger 11, preferably axially symmetric, which can move parallel to the main direction A (along a trajectory for intercepting the electrode 4) and is partially accommodated so that it can slide within a respective chamber 12, which in turn is preferably cylindrical or axially symmetric.

[0046] Sealing elements, which may be conventional, are used between the plunger 11 and (the delimiting wall of the) chamber 12 so as to guard against the danger of leaks.

[0047] The chamber 12 is provided internally with a first compartment 13a and a second compartment 13b, which are separated (delimited) by the plunger 11.

[0048] At least the first compartments 13a, i.e. the compartments arranged on the opposite side from the corresponding electrode 4, are placed in mutual communication by means of a compensation circuit 14, which during use is kept closed and filled with a pressurized fluid, which in turn is adapted to keep the presser elements 10 in the active configuration.

[0049] Therefore, "active configuration" refers to any position that the plunger 11 can assume in its translation (sliding) motion parallel to the main direction A, in which it can press against the electrode 4, directly or indirectly, in particular because it is pushed on its other side by the pressurized fluid. In the preferred embodiment, which in any case is not limiting of the invention, the second compartments 13b are also placed in mutual communication by means of an auxiliary circuit 15, which during use is kept closed and preferably filled with air.

[0050] In other words therefore, and as can be seen for example in Figures 8 and 9, the space delimited by each chamber 12 is partially occupied by the respective plunger 11: the portions of the compartment that are not occupied by the plunger 11, the volumes of which are variable by virtue of the movement of the latter, naturally constitute the compartments 13a, 13b.

[0051] At rest, the presser elements 10 and the plungers 11 in particular are at level "zero", at which they are already in the active configuration and press directly or indirectly against the respective electrode 4, or in any case they are in direct contact with the electrode 4 itself, and are kept in that condition by the pressurized fluid in the first compartments 13a and by the equilibrium of forces generated with the opposing thrust produced by the air in the second compartments 13b (or produced in some other way).

[0052] When the assemblies 3a, 3b are brought mutually close together to clamp the workpieces, a possible irregularity of flatness imposes a displacement (even if slight) in a plunger 11 (or in one of the plungers). This displacement is reflected in a pressure on the fluid contained in the corresponding first compartment 13a, which, through the compensation circuit 14, is in communication with the other first compartments 13a. Thus, a greater pressure is automatically generated on the other plungers 11 by virtue of the balancing action of the pressurized fluid, which makes it possible to (constantly) keep all the plungers 11 under sufficient pressure against the electrode 4, so achieving the set aim.

[0053] In particular, in the preferred embodiment, the fluid that fills the compensation circuit 14 is hydraulic oil; however, the possibility is not ruled out of using another liquid, or even air or another gas.

[0054] The oil, or other fluid, is preferably degassed, so as to reduce or eliminate any elasticity of response.

[0055] It should be noted however that the role of the auxiliary circuit 15 and in general of the air that fills the second compartments 13b is to contribute to the definition of the "level zero" at which the plungers 11 are normally kept when they are not subjected to forces; a similar role could also be played by springs. More generally, the device 1 can be provided with any suitably powered device that can return the plungers 11 to the "level zero" mentioned above.

[0056] Usefully, the plungers 11 can be arranged in a mutually parallel manner along one or more mutually parallel rows, oriented at right angles with respect to the main direction A. The arrangement of the plungers 11 will in any case be such as to keep them practically at the same longitudinal elevation (the elevation defined by the main direction A), so as to be able to react adequately to any irregularity in flatness.

[0057] In particular, in the embodiment in the accompanying figures, see for example Figure 6, the device 9 comprises three plungers 11 aligned along a (single) row; any matrix (or other form of) distribution should in any case be understood to be included in the scope of protection claimed herein. The choice in this regard can for example depend on the dimensions and shapes of the workpieces to be treated (and of the electrode 4), and also on the desire to ensure a greater or lesser distribution of the pressure stresses along the full extent of the surfaces involved.

[0058] With further reference to the preferred embodiment, proposed in the accompanying figures for the purposes of non-limiting example of the invention, the device 9 can comprise a plate 16 (preferably but not necessarily made of metallic material), which has, along a face 16a thereof which is directed toward the respective electrode 4, a plurality of openings 17 for access to respective chambers 12, which are provided within the plate 16.

[0059] As can be seen for example in Figures 8 and 9, at least a part of the circuits 14, 15 can be provided within the plate 16.

[0060] Usefully, the device 9 can comprise at least one verification instrument 18, which is configured for detecting the pressure value in the compensation circuit 14. For example therefore, if a pressure value is detected that is lower than desired, the operator can temporarily access the compensation circuit 14 (when the apparatus 1 is not in use) to add oil (or other fluid) and restore the desired value.

[0061] The instrument 18 can for example be (or comprise) a pressure switch, which as in the accompanying figures is facing a portion of the compensation circuit 14.

[0062] In any case any other component can be used, including components of commercial type, which the person skilled in the art would be able to deem suitable for performing the task indicated above.

[0063] In the preferred embodiment, which in any case does not limit the application of the invention, the device 9 comprises a plurality of flanges 19, which are stably interposed between respective plungers 11 and the delimiting wall of the corresponding chambers 12.

[0064] The flanges 19 (preferably cylindrical or axially symmetrical) facilitate the mounting of the device 9 and of the presser elements 10 in particular; they can furthermore accommodate at least one part of the auxiliary circuit 15.

[0065] Usefully, at least one of the circuits 14, 15 comprises at least one venting branch 14a, 15a, which is open outward at an orifice which is closed by a removable plug 14b, 15b.

[0066] In more detail, preferably both the circuits 14, 15 are provided with one or more respective venting branches 14a, 15a, as shown clearly in Figures 8 and 9.

[0067] With further reference to Figures 8 and 9, the venting branches 14a of the compensation circuit 14 can for example be provided at least partially in the plate 16 and / or in the plungers 11, while the venting branches 15a of the auxiliary circuit 15, as previously mentioned, can be provided partly in the flanges 19, as well as in the plate 16.

[0068] In the preferred form, (at least) the first assembly 3a can also comprise an abutment plate 20, which is interposed between the device 9 and the respective electrode 4: in such case, the presser elements 10 are adapted to apply, at least in the active configuration, a (direct) pressure to the plate 20 and therefore, indirectly, a pressure on the electrode 4.

[0069] Even more specifically, both the abutment plate 20 and the plates 8 passed through by current can be interposed between the device 9 and the respective electrode 4.

[0070] Usefully, the device 9 is self-sufficient from an energy standpoint. In fact, as has been seen, the movement and the position assumed by the plungers 11 (with respect to the translation trajectory permitted to them), and also their return to level "zero", are determined solely by the pressurized fluid in the first compartments 13a (and, for example, by the air in the second compartments 13b), with no need for external energy or power sources.

[0071] The operation of the apparatus 1 has effectively already been explained: the treatment of the workpieces occurs according to methods that are traditional per se, by virtue of the clamping of those workpieces between the assemblies 3a, 3b and the electrodes 4 in particular, but, in an entirely particular and innovative manner, by virtue of the device 9 any irregularity of flatness is effectively compensated, be it in the workpieces being treated or in the components of the apparatus 1 in play.

[0072] In fact, in conventional solutions, irregularities of flatness generate uneven forces which ensure that the pressure on the clamped workpieces is not uniform for all of the surfaces in contact (with grave consequences for the quality of the weld / of the permanent bond obtained). By contrast, in the apparatus 1 such irregularities cause a translation movement of one or more plungers 11 , but this is immediately compensated by the pressurized fluid in the first compartments 13a: when the irregularities "displace" one or more plungers 11, the pressurized fluid contained in the first compartments 13a redistributes the corresponding pressure gradients generated by the displacement to the other plungers 11 (by virtue of the fact that all the first compartments 13a are in communication via the compensation circuit 14) and therefore the uneven forces are balanced and compensated. The corresponding electrode 4 is therefore constantly pressed against the workpieces with uniform and constant pressure on all the surfaces involved.

[0073] This makes it possible to obtain the permanent bonding of workpieces of any shape and size, while still ensuring high quality and consistency of the result obtained, even in the presence of irregularities in the flatness of the workpieces or of the components of the apparatus itself. In particular, the apparatus 1 can carry out "diffusion bonding" treatments on workpieces of large dimensions, ensuring high quality and consistency of the result obtained.

[0074] By virtue of the perfect adhesion of the surfaces and of the workpieces to be bonded, the apparatus 1 requires a decidedly reduced consumption of current to execute the permanent bonding required, and this enables the apparatus 1 to operate effectively, even on workpieces of large dimensions, while still improving the contact between the surfaces and the apparatuses. As has been seen, the device 9 does not require any external power source, thus ensuring once again reduced energy consumption for the apparatus 1 of which it is part.

[0075] The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims. Moreover, all the details may be substituted by other, technically equivalent ones.

[0076] In the embodiments illustrated, individual characteristics shown in relation to specific examples may in reality be substituted with other, different characteristics, existing in other embodiments. In practice, the materials employed, as well as the dimensions, may be any according to requirements and to the state of the art.

[0077] The disclosures in Italian Patent Application No. 102024000016852 from which this application claims priority are incorporated herein by reference.

[0078] Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.

Claims

CLAIMS1. A workpiece treatment apparatus, comprising at least one frame (2) for supporting two clamping assemblies (3a, 3b), which are provided with the capacity for relative translation along a main direction (A) of mutual approach and spacing apart, said assemblies (3a, 3b) comprising respective electrodes (4) which face each other and are configured for clamping a pair of workpieces to be permanently bonded, characterized in that at least one first said assembly (3a) comprises a compensation device (9); said device (9) comprising a plurality of presser elements (10) adapted to exert, in at least one active configuration, a direct or indirect pressure on the respective said electrode (4) which is directed towards the other said electrode (4), each of said presser elements (10) comprising a plunger (11) which can move parallel to said main direction (A) and is partially accommodated so that it can slide within a respective chamber (12), which has a first compartment (13 a) and a second compartment (13b) which are separated by said plunger (11), at least said first compartments (13a), which are arranged on the opposite side from the corresponding said electrode (4), being placed in mutual communication by means of a compensation circuit (14), which during use is closed and filled with a pressurized fluid, and which is adapted to keep said presser elements (10) in said active configuration.

2. The apparatus according to claim 1, characterized in that said second compartments (13b) are placed in mutual communication by means of an auxiliary circuit (15), which during use is closed and preferably filled with air.

3. The apparatus according to claim 1 or 2, characterized in that said fluid is hydraulic oil.

4. The apparatus according to one or more of the preceding claims, characterized in that said plungers (11) are arranged in a mutually parallel manner along one or more mutually parallel rows oriented at right angles to said main direction (A).

5. The apparatus according to one or more of the preceding claims, characterized in that said device (9) comprises a plate (16) which has, along a face (16a) thereof which is directed toward the respective said electrode (4), a plurality of openings (17) for access to respective said chambers (12), provided within said plate (16).

6. The apparatus according to one or more of the preceding claims, characterized in that said device (9) comprises at least one verification instrument (18) configured for detecting the pressure value in said compensation circuit (14).

7. The apparatus according to claim 6, characterized in that said instrument (18) is a pressure switch, which faces a portion of said compensation circuit (14).

8. The apparatus according to one or more of the preceding claims, characterized in that said device (9) comprises a plurality of flanges (19), which are stably interposed between respective said plungers (11) and the delimiting wall of said corresponding chambers (12).

9. The apparatus according to one or more of the preceding claims, characterized in that at least one of said circuits (14, 15) comprises at least one venting branch (14a, 15a), which is open outward at an orifice which is closed by a removable plug (14b, 15b).

10. The apparatus according to one or more of the preceding claims, characterized in that said first assembly (3a) comprises an abutment plate (20), which is interposed between said device (9) and said respective electrode (4), said presser elements (10) being adapted to apply, in at least said active configuration, a pressure to said plate (20).

11. The apparatus according to one or more of the preceding claims, characterized in that said device (9) is self-sufficient from an energy viewpoint.

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