Component with deformable pads

Abstract

Component (40) for contact with a counter-component (50) during the fastening of the components (40, 50) to each other, wherein the component (40) has: a body (12) with an interface (24, 42), wherein the body (12) is able to come into contact with the opposite component (50) at the interface (24, 42) of the body (12); and at least one deformable pad (26) formed at the interface (24, 42), wherein the at least one deformable pad (26) has an upper surface (28) which is offset outwards relative to the interface (24, 42) and the body (12), wherein the at least one deformable pad (26) has a groove (30) surrounding the at least one deformable pad (26), the groove (30) being offset inwards relative to the interface (24, 42) and the body (12).

Description

BACKGROUND

[0001] This invention relates to features on a surface of a component, wherein the surface of the component is brought into contact with another surface by clamping pressure or loading.

[0002] Components are often connected together using pins or other fasteners. For example, a bearing cap may be attached to a mating component by tucking, bracing, or otherwise enclosing a bearing element between two semicircular surfaces found on the bearing cap and mating component, respectively. Typically, the bearing cap is attached to the mating component by inserting pins through two legs of the bearing cap, with the two legs straddling the semicircular area housing the bearing element. Once these pins are tightened, the bearing element is enclosed between the bearing cap and the mating component.

[0003] In this example, to correctly balance stresses during the fastening process, it is often necessary to carefully control the manner in which the bolts are tightened. If the bolt on one side is tightened too tightly before the bolt on the other side has been sufficiently tightened, there is a possibility that the bearing element held between the bearing cap and the mating element will be subjected to uneven stress around its circumference, and this uneven stress could cause the round configuration of the bearing to become compressively deformed. Because bearing elements are precision components, even slight deformation from a round shape is potentially damaging to the bearing elements and can render the bearing element less efficient or even unusable.

[0004] In addition, uneven tightening of the pins during assembly of the two mating components can also cause cracks in the bearing cap or even break the bearing cap. If the pins are not tightened evenly during assembly, the bearing cap may be subjected to varying stresses in its legs, which it cannot withstand based on its specifications.

[0005] Consequently, conventional practice has evolved to tighten the two pins simultaneously during mating, preventing the development of differential stresses across the legs. However, such simultaneous tightening can be complicated to implement and, if not performed correctly, can still result in the application of uneven stresses, damaging the components currently being mated.

[0006] Thus, there remains a need for improvements in the interconnection of multiple components while avoiding many of the problems caused by different stresses being induced during the joining process.

[0007] From WO 2013 163 410 A1 a bearing cap is known which has a pair of pin holes and next to them two elongated elevations.

[0008] A filter is known from US 2 808 937 A.

[0009] The object of the present invention is to at least partially solve the problems cited with reference to the prior art. In particular, a component designed to contact a mating component during the fastening of the components to one another, as well as a device comprising a component and a mating component, are proposed, which enable improved control over the stresses induced during the joining of the components.

[0010] A component having the features according to claim 1 and a device having the features according to claim 9 contribute to the solution of these objects. OVERVIEW OF THE INVENTION

[0011] To enable improved control over the stresses induced during assembly of the components, powder metal components are disclosed which have one or more deformable pads formed on a surface of the components. These deformable pads are formed on a surface of the component and are configured to contact a surface of another component under compaction or compression at an interface between the two components. First, the upper surface of the deformable pad is disposed over the interface of the components (i.e., away from the body of the components) such that when the two components are brought into contact under load, the pad is deformable downwardly into the surface of the component. There may be a trench or "relief groove" whichwhich accommodates the deformation of the pad in a direction substantially perpendicular to the direction of the load applied to the body of the components.

[0012] According to one aspect of the invention, a component is disclosed which is intended to come into contact with a mating component during fastening of the components together. The component comprises a body having an interface, the body being capable of being brought into contact with the mating component at the interface of the body. The component has one or more deformable pads formed at the interface. The deformable pad or pads each have an upper surface which is offset outwards relative to the body from the interface. The deformable pad or pads further have a groove surrounding the respective pad, the groove being offset inwards relative to the body from the interface.

[0013] The component may be a powder metal component, and the body may be a powder metal body. According to some embodiments, the powder metal component may be aluminum or an aluminum alloy.

[0014] According to a specific embodiment, the component may be a bearing cap for an axle shaft. The bearing cap may have a pair of pin holes. Two deformable pads may be provided near an opening of each pin hole at the interface. The centers of the deformable pads may be separated by 180 degrees around the opening of each pin hole. According to some embodiments, the two deformable pads may be positioned along a line passing through the axes of the two pin holes.

[0015] According to a further aspect of the invention, a component of the type described above can be attached to a mating component to form a device. The device comprises a component having a body having an interface with one or more deformable pads formed at the interface. Each deformable pad has a top surface offset outwardly from the interface relative to the body and a groove surrounding the deformable pad that is offset inwardly from the interface relative to the body. The device further comprises a mating component having an interface. The interface of the body of the component contacts the interface of the mating component (or the interface contacts an intermediate sealing ring).In order for the interfaces to contact each other (or the sealing ring), the mutual connection of the component and the mating component occurs under an applied load to deform the deformable pad or pads.

[0016] To connect the component and the mating component, the device may further comprise pins by means of which the component is fastened to the mating component. These pins can generate the load required to deform the deformable pad or pads such that the interfaces contact each other. It may be contemplated that, for other types of devices, fastening elements other than pins may be used, or that a clamping force between the component and the mating component may also be generated in other ways.

[0017] To better accommodate the deformation of the deformable pad(s), the materials of the device can be selected such that the mating component is harder and less deformable than the component with the deformable pad. This ensures that the deformable pad(s) form the feature that exhibits the most deformation.

[0018] Again, one or both of the component and the mating component may be formed as powder metal components (i.e., powder metal components formed by powder metal processes such as compacting and sintering powder metal to form a single-piece powder metal body). According to some embodiments, the powder metal component may be formed from aluminum or an aluminum alloy.

[0019] In the device, the component may be a bearing cap for an axle shaft and may have a pair of pin holes used to secure the component and the mating component by means of pins. Deformable pads of various arrangements and configurations may be positioned along the interface, particularly in the region of the pin holes.

[0020] These and other advantages of the invention will become apparent from the detailed description and drawings. The following is merely a description of some preferred embodiments of the present invention. The claims should be consulted for the full scope of the invention, as these preferred embodiments should not be construed as the only embodiments within the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows a perspective view of a deformable pad formed at an interface of an end of a leg of a powder metal component that is a bearing cap. Fig. Figure 2 shows a bottom plan view of the bearing cap, showing a possible placement of the deformable pads around ends of the two legs. Fig. Figure 3 shows a diagram comparing two cases of contact, where in one of these cases, the one in Fig. 3a (case 1), no deformable pad is present, and in the other of the cases, shown in Fig. 3b (case 2), a deformable pad is present. Fig. Figure 3c shows the initial deformation of the deformable pad under application of a compressive load. DETAILED DESCRIPTION

[0021] In the first to be described Fig. 1 shows one end of an exemplary bearing cover 10 in perspective. Furthermore, Fig. 2 shows a bottom view of the entire bearing cap 10. The bearing cap 10 has a body 12 with a central portion 14, which is provided on opposite sides with a first leg 16 and a second leg 18. As can be seen from the underside of the bearing cap 10, a semicircular surface 20 is formed on the central portion 14, which is arranged centrally between the two legs 16 and 18 and serves to receive a bearing element during assembly of the bearing cap 10 to a mating component. (The mating component has an opposite semicircular surface so that the bearing element can be received and held between the semicircular surfaces.)

[0022] At the Fig. 1, a pin hole 22 extends through the first leg 16, through which a pin can extend in order to fasten the bearing cover 10 to the other, ie the mating component. Since the Fig. 1 and Fig. 2 is located at the end of the bearing cap 10 opposite the mating component, the threaded end of the pin extends through and out of the opening shown in these figures to threadably engage an opening of the mating component. An interface 24 at the end of the leg 16 surrounds the opening of the pin hole 22, and this interface 24 extends substantially perpendicular to the axis of the pin hole 22.

[0023] In Fig. 2, a pin hole 22 and interface 24 are shown at one end of the second leg 18, similar to the pin hole 22 and interface 24 located at the end of the first leg 16. Thus, in the embodiment shown, the two legs 16 and 18 are formed substantially symmetrically about the central portion 14 of the bearing cap 10.

[0024] Again according to the Fig. 1, a deformable pad 26 is positioned at the interface 24 around the pin hole 22. Although in Fig. 1 only a single deformable pad 26 is shown due to the specific area shown, several pads 26 may also be present around each of the pin holes 22, as in Fig. 2. In the embodiment shown, these deformable pads 26 are arranged on opposite sides of each of the pin holes 22, and the pads 26 are separated by 180 degrees around the central axis of the pin hole 22. In some embodiments, these pads 26 may be arranged along a centerline passing through both pin hole axes to avoid torsional loads on the part being clamped (i.e., the bearing element). However, in the embodiment shown, the pads 26 are rotated 90 degrees with respect to this centerline. The pads 26 may also assume other arrangements around the pin holes. For example, the pads 26 may be rotated approximately 45 degrees with respect to this centerline on the interfaces. Alternatively, these pads 26 may be provided in different quantities or arrangements.For example, three, four or more pads 26 may be arranged around each of the pin holes 22.

[0025] Furthermore, the pads 26 are in no way limited to the Fig. 1 and Fig. 2. The pads 26 may take any of a number of different shapes. According to a particular embodiment, the deformable pad 26 may be doughnut-shaped and form a ring around the opening of the pin hole 22 at the interface 24.

[0026] The upper peak, upper plateau, or upper surface region 28 of the deformable pad 26 is located away from the body 12 of the bearing cap 10 relative to the interface 24. In the particular embodiment shown, the upper surface 28 is parallel to the interface 24 and is offset outwardly relative to the body 12 (i.e., away from the bulk of the material of the body 12). This upper surface 28 defines the initial area of ​​contact between the bearing cap 10 (or any other component on which it is formed) and the mating component.

[0027] Preferably, the deformable pad or pads are formed integrally with the powder material body 12. Each deformable pad 26 includes a stem, which may be formed from the same material as the base component or from a different material, as may be the case with a composite component where more than one type of material is used to form the component. The function of the stem is to undergo plastic-elastic deformation under compressive loads as its cross-sectional area increases, and to increasingly resist deformation (plastic deformation capacity) under further increasing loads.

[0028] The deformable pad 26 further includes a relief groove 30 or trench surrounding the area of ​​the deformable pad 26. This groove 30 is offset relative to the interface 24 toward the body 12 of the bearing cap 10. The groove 30 is configured to accommodate the laterally outward deformation or mushrooming of the deformable pad 26 when the bearing cap 10 and the mating component are mated under compressive loading or clamping force, forcing the upper surface 28 of the deformable pad 26 against the interface of the mating component.This deformable pad 26 and the relief groove 30 can be geometrically dimensioned to limit and control the relative displacement of the component (in the present example, the bearing cap 10) relative to the interface of another mating component when the component and the mating component are subjected to clamping or tightening loads during assembly of the components. The groove 30 is arranged at the base of the stem of the deformable pad 26 and can allow the stem to expand or deform completely below the interface 24 when the interface 24 is in contact with the mating component. This means that the interface 24 of the component having the deformable pads 26 and the corresponding surface of the other, ieCounter component can be made flush with each other, provided that the groove 30 is formed with sufficient volume to initially accommodate the volume of the shaft or the pad 26 located above the interface 24.

[0029] The general function of the pads 26 is to minimize the displacement of the adjoining components subjected to a load in a specific area, thereby reducing the maximum stresses and the stress range associated with any overloads acting on the bodies, except at the location of the applied loads and the interface contact. The materials selected for each of the components and the design parameters of the deformable pad and the corresponding relief groove may be selected to achieve the desired deformation profile across the range of loads during clamping.

[0030] In the case of a powder metal component, in this case the bearing cap 10, the deformable pad or pads 26 may be created during the compaction and sintering of the powder metal material to form the powder metal component. The tooling used to compact the powder may have the negative mold of the deformable pad or pads formed in the tool, so that the deformable pad or pads are formed in the preform during the compaction step before sintering occurs. Often, the manufacturing steps for forming the powder metal component may also include additional processing steps. These additional processing steps may include finishing steps such as drilling to achieve the final dimensions of the pin holes 22 or grinding to achieve the flat configuration of certain surfaces of the component.

[0031] As a result, if the component including the deformable pads 26 is formed from a powder metal material, the component may remain in a less than fully dense state, as powder metal components typically exhibit some degree of porosity even after sintering. According to a particular embodiment, the component may be a powder metal component formed by liquid-phase sintering and may have a density of 98% of theoretical.

[0032] Furthermore, it should be appreciated that the materials of the components can be selected to ensure that the deformable pad deforms elastically or plastically, rather than being pressed or impressed into the surface of the mating component. Accordingly, the deformable pad can be formed from a comparatively softer or more easily deformable material than the material of the mating component, which can be formed from a comparatively harder or less deformable material. According to one embodiment, the component provided with the deformable pads can comprise aluminum or an aluminum alloy. According to some embodiments, the deformable pads can have a density that differs from that of the majority of the mass of the component, thereby making the deformable pads comparatively more easily deformable.Because sintered powder metal pads are typically less than completely dense, powder metal parts often have some degree of internal porosity. According to yet further embodiments, the deformable pads could be formed from a different powder material that is more easily deformable or can be treated in another way. For example, the component's deformable pads can be masked during heat treatment or carburization (which adversely alters deformability) to improve the deformability of the pads relative to the other components.

[0033] To form a device comprising the powder metal component or the bearing cap 10, the component is pressed against a mating component such that an interface of the component faces an interface of the mating component. Since the interface of the component includes deformable pads, these deformable pads initially contact the interface of the mating component. It will be appreciated that according to some embodiments, only one of the components may have deformable pads, while according to other embodiments, both components may have deformable pads contacting the opposing interface. In either case, the components are then subjected to a compressive load (which may be applied by tightening pins or similar fasteners) to draw the component and the mating component together.When this compressive force is applied, the deformable pads mushroom out or deform into the relief grooves, while the interfaces are pulled toward each other. This creates a controlled and predictable application of stress and deformation to the components as they are tightened against each other.

[0034] Finally, the component with the deformable pad(s) and the mating component can come into direct contact with each other at the interfaces. According to some alternative embodiments, a sealing ring can be enclosed between the two interfaces, and the height dimension of the deformable pad(s) and the elastic properties of the pads can be designed to exert a desired degree of pressure on the sealing ring enclosed between the interfaces of the components.

[0035] According to one embodiment, the component device may be a hemispherical bearing cap for an axle shaft on the front-wheel drive portion of a vehicle. In this case, there is typically a pair of pin holes used to secure the bearing cap to the mating component. For such a component, one or more deformable pads positioned around each of the pin holes may be used. When tightening pins holding bearing caps of this type, the pins typically need to be tightened simultaneously to prevent the bearing cap from breaking. By using these deformable pads, the ability to tighten the pins separately without causing damage to the bearing cap can be improved.

[0036] It may be envisaged that the clamping arrangement provided with deformable pads described in this application may also be used for devices other than those intended for holding a bearing. Furthermore, although the device components preferably comprise at least one powder metal component, it may be envisaged that none, one, or both of the components are formed from powder metal. The components could possibly be formed in other ways (e.g., by casting instead of using powder metal production techniques), and the materials of the two components could be similar (e.g., two aluminum or two ferrous powder metal parts could be bonded together) or dissimilar (e.g., an aluminum powder metal component could be attached to a ferrous powder metal component).

[0037] In the now to be explained Fig. Figure 3 illustrates two cases where a component and a mating component are compressively secured to form a device. In the situation where the component is a bearing cap and the mating component is a component to which the bearing cap is secured by pins to form a device, the compressive force P is the force exerted by the pins to connect the two components.

[0038] A first case, Case 1, is in Fig. 3a, in which case no deformable pads are present on either component. In Case 1, a component 40 and a counter-component 50 are shown directly before the interface 42 of the component is pressed against the interface 52 of the counter-component 50, which occurs under a compressive load P. The component 40 and the counter-component 50 each have a spring constant k, assuming that they are made of similar materials. The component 40 has a height h1, and the counter-component 50 has a height h2. In Case 1, the total displacement d1 during compression can be modeled according to the following equation: d1=d(h1,k)+g+d(h2,k) where d(h, k) is the displacement of the component under the load P as a function of the height of the component and its spring constant k, and where g is the distance between the components.

[0039] This is compared to case 2, which was Fig. 3b, and in which the deformable pad 26 is further provided on one of the components 10. In Case 2, the deformable pad 26 has a height g that extends above the interface 24 of the component 10 and a spring constant k' that differs from the spring constant k of the material of the mating component 50 and the component 10. If the components are otherwise similar to those present in Case 1, but with the addition of the deformable pads 26, and are subjected to a compressive load P, the displacement d2 in Case 2 can be modeled according to the following equation: d2=d(h1,k)+d(g,k′)+d(h2,k) where the term d(g, k') replaces the term g of the equation given above for modeling case 1 and represents the displacement of the deformable pad 26.

[0040] Since, for a given applied load P, the value of d(g, k') in case 2 is less than or equal to the value of g in case 1, and the other terms in the equations are identical, it can be assumed that the load σ1 applied in the first case at a particular location on one of the components currently being fastened together is greater than or equal to the load σ2 applied in the second case at a similar location on the components.

[0041] In the detailed view according to Fig.3c, to which reference is made hereinafter, the initial deformation of the deformable pad 26 can be seen. The solid lines show the initial geometry of the component 10 and the deformable pad 26. The dashed line B shows the new profile of the deformable pad 26 at the beginning of the application of the clamping force. Under the compressive load P, the deformable pad 26 begins to mushroom outwardly, or deform, and it begins to fill the space of the relief groove 30, which is generally represented by the dashed line A. Upon further compression, the relief groove 30 continues to fill with the material of the deformable pad 26 until the interfaces 24 and 52 come into contact with each other (or, depending on the particular arrangement, come into contact with an intermediate sealing ring). Within this deformation range (i.e.From the initial part geometries to the contacting of the interfaces with each other or with an intermediate sealing ring, if the device is designed for this purpose), a very tightly controlled deformation and displacement takes place, which is induced under the applied load.

[0042] It should be understood that various further modifications and variations to the preferred embodiments may be made within the spirit and scope of the invention. Thus, the invention is not to be limited to the described embodiments. Reference is made to the following claims for a full scope of the invention.

Claims

[1] Component (40) for contact with a mating component (50) during attachment of the components (40, 50) to one another, the component (40) comprising: a body (12) having an interface (24, 42), the body (12) being capable of being brought into contact with the counter component (50) at the interface (24, 42) of the body (12); and at least one deformable pad (26) formed at the interface (24, 42), wherein the at least one deformable pad (26) has a top surface (28) that is offset outwardly from the interface (24, 42) relative to the body (12), wherein the at least one deformable pad (26) has a groove (30) surrounding the at least one deformable pad (26), wherein the groove (30) is offset inwardly from the interface (24, 42) relative to the body (12). [2] The component (40) of claim 1, wherein the component (40) is a powder metal component and the body (12) is a powder metal body. [3] Component (40) according to claim 2, wherein the powder metal component is formed from aluminum or an aluminum alloy. [4] Component (40) according to claim 1, wherein the component (40) is a bearing cap (10) for an axle shaft. [5] Component (40) according to claim 4, wherein the bearing cap (10) has a pair of pin holes (22). [6] The component (40) of claim 5, wherein the at least one deformable pad (26) comprises two deformable pads (26) proximate an opening of each pin hole (22) at the interface (24, 42). [7] A component (40) according to claim 6, wherein the centers of the two deformable pads (26) are separated by 180 degrees around the opening of each pin hole (22). [8] Component (40) according to claim 7, wherein the two deformable pads (26) are positioned along a line passing through the axes of the two pin holes (22). [9] Device with: a component (40) having a body (12) having an interface (24, 42), at least one deformable pad (26) formed at the interface (24, 42), the at least one deformable pad (26) having a top surface (28) that is offset outwardly from the interface (24, 42) relative to the body (12), the at least one deformable pad (26) having a groove (30) surrounding the at least one deformable pad (26), the groove (30) being offset inwardly from the interface (24, 42) relative to the body (12); a counter component (50) having a boundary surface (24, 42), wherein the interface (24, 42) of the body (12) of the component (40) contacts the interface (52) of the mating component (50), and wherein the component (40) and the mating component (50) are bonded together under an applied load to deform the at least one deformable pad (26). [10] The apparatus of claim 9, further comprising pins securing the component (40) to the mating component (50), wherein the applied load for deforming the at least one deformable pad (26) is generated by the pins. [11] Apparatus according to claim 10, wherein the counter component (50) is harder and less deformable than the component (40), thereby absorbing the deformation of the deformable pads (26) of the component (40). [12] Device according to claim 9, wherein at least one of the component (40) and the counter-component (50) is a powder material component. [13] Apparatus according to claim 9, wherein the powder material component is formed from aluminum or an aluminum alloy. [14] Device according to claim 9, wherein the component (40) is a bearing cap (10) for an axle shaft. [15] Apparatus according to claim 14, wherein the bearing cap (10) has a pair of pin holes (22). [16] The device of claim 15, wherein the at least one deformable pad (26) comprises two deformable pads (26) proximate an opening of each pin hole (22) at the interface (24, 42). [17] The device of claim 16, wherein the centers of the two deformable pads (26) are separated by 180 degrees around the opening of each pin hole (22). [18] Device according to claim 17, wherein the two deformable pads (26) are positioned along a line passing through the axes of the two pin holes (22).

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