Solenoid valve structure

Abstract

Solenoid valve (900) comprising a valve body (1) in which pneumatic connections and a valve seat are obtained, the latter alternately putting in fluidic communication at least two of said pneumatic connections, and a driving assembly operatively connected to the valve body (1). The driving assembly comprises a coil (20) for generating a magnetic field, identifying a central seat coaxial with a coil axis. Moreover, the driving assembly comprises a movable core (22), arranged coaxially to the coil (20) and axially translatable between a first closing position of the valve seat and a second opening position of the valve seat, and a fixed core (24), also arranged coaxially to the coil (20). The driving assembly further comprises an armature made of ferromagnetic material and magnetically coupled to the coil (20) so as to close the lines of force of the magnetic field generated by the coil (20). The armature comprises a head portion (260) extending in a direction substantially transverse to the coil axis, a side portion (262) extending in a direction substantially parallel to the coil axis, and a base portion (264) extending in a direction substantially transverse to the coil axis opposite to the head portion (260), wherein an axial through opening is obtained in the base portion (264), in which the movable core (22) is partially housed and sliding. The driving assembly comprises a polar expansion (266) surrounding the movable core (22) so as to increase the interface surface between the movable core (22) and the flux lines of the magnetic field, wherein the polar expansion (266) is made in one piece in a single body with the base portion (264) of the armature.

Description

SOLENOID VALVE STRUCTUREDESCRIPTION

[0001] The present invention relates to the field of solenoid valves and, in particular, to an armature and a method for producing such an armature for solenoid valves .

[0002] In the prior art , there are solenoid valve solutions having a magnetic circuit in which the magnetic field produced by a coil is induced . The magnetic circuit must be designed to facilitate the sealing of the fluid with other components of the solenoid valve so as to avoid fluid leaks even when the solenoid valve operates at high pressures . An example of a solenoid valve of the prior art is shown in Figures la and lb .

[0003] One of the problems of these types of solenoid valves is that the magnetic circuit , being made by the coupling of di f ferent ferromagnetic elements , forms air gaps which, together with the need to make sealing interfaces with other components of the valve , generate areas of dispersion of the lines of the magnetic field .

[0004] A further problem that arises from the complexity of the magnetic circuit of the solenoid valve of the prior art is the consequent complexity of the sealing system, which must necessarily adapt to the numerous interface surfaces that are created between the components once the solenoid valve is assembled .

[0005] For example, in the solenoid valve of Figures la and lb, the magnetic circuit is formed by a coil 3020 made of a wire wound on a spool 3210, an armature 3026 magnetically coupled to the coil 3020, a fixed core 3024 arranged coaxially to the coil 3020, a movable core 3022, also arranged coaxially to the coil 3020, and a polar expansion 3266 separated from the armature 3026. The magnetic circuit of the solenoid valve of the known art is operatively connected to the valve body 3001.

[0006] With reference to Figures la and lb, the solenoid valve of the prior art has a sealing system composed of three sealing rings, also called "O-rings". The first sealing ring 3310 is positioned between the polar expansion 3266 and the pneumatic valve body 3001, the second sealing ring 3312 is positioned between the polar expansion 3266 and the bobbin 3210, and the third sealing ring 3314 is positioned between the fixed core 3024 and the bobbin 3210.

[0007] Therefore, also considering the fact that many applications require increasingly miniaturized solenoid valves, it is evident that the solenoid valves of the known art suffer from some limitations related to the efficiency of the magnetic circuit and the difficulty in the making and assembling of the valve components.

[0008] An object of the present invention is to propose a solenoid valve, a magnetic circuit armature and itsmethod of production, capable of overcoming at least in part the drawbacks of the known art mentioned above .

[0009] Said obj ect is achieved by means of a solenoid valve in accordance with claim 1 , an armature for such solenoid valve according to claim 10 and a related method of production according to claim 12 .

[0010] Further characteristics and advantages of the invention will appear from the description below of its preferred embodiments , given by way of descriptive and non-limiting example , with reference to the annexed figures , in which :

[0011] - Figures la and lb respectively show a perspective view and a sectional view of a solenoid valve of the known art ;

[0012] - Figure 2 shows an exploded view of the components of a solenoid valve according to the invention;

[0013] - Figure 3 is a perspective axial section of the solenoid-armature group according to the invention, in which the three planes in which the head, side and base portions of the armature extend are highlighted;

[0014] - Figure 4 is a perspective axial section of a solenoid valve according to one embodiment of the invention;

[0015] - Figure 5 is another perspective view, in partial section, of the solenoid valve according to theinvention;

[0016] - Figure 6 is a sectional view of the solenoid valve according to the invention;

[0017] - Figure 7 is a perspective view in partial section of the solenoid valve according to the invention;

[0018] - Figure 8 is an enlarged axial section of the portion of solenoid valve at the engagement between the armature and the fixed core and between the fixed core and the movable core;

[0019] - Figure 9 shows a sequence of steps of the method for producing an armature for the solenoid valve according to the present invention.

[0020] With reference to the attached figures, the number 900 denotes a solenoid valve according to the invention as a whole.

[0021] The solenoid valve 900 comprises a valve body 1 in which pneumatic connections 1000 and a valve seat 100 are obtained.

[0022] According to one embodiment, the valve seat 100 alternately puts in fluidic communication at least two of the pneumatic connections. In fact, the valve seat 100 allows retention or release of the fluid contained inside the valve body 1 when it is respectively closed or open.

[0023] Moreover, a valve body cavity 10 is obtained in the valve body 1.

[0024] According to one embodiment, the valve body cavity 10 has a substantially cylindrical shape and is obtained around the valve seat 100 . Consequently, the valve body cavity 10 is internally delimited by a cylindrical side surface 12 .

[0025] Moreover, the solenoid valve 900 comprises a driving assembly 2 operatively connected to the valve body 1 . As described in detail in the following description, the driving assembly 2 allows control of the operation of the solenoid valve 900 by determining its opening and closing .

[0026] The driving assembly 2 comprises a coi l 20 for generating a magnetic field .

[0027] The coil 20 is made of a wire wound on a spool 210 . According to one embodiment , the spool comprises power supply terminals for supplying the supply current to the coil 20 . In fact , in order for the coil 20 to generate the magnetic field necessary for the operation of the solenoid valve , that is , for the movement of the movable core , the coil 20 must be traversed by the supply current . Therefore , the power supply terminals allow the coil 20 to be supplied with the supply current necessary for generating the magnetic field .

[0028] Preferably, the power supply terminals are fasten terminals made of copper and aluminium-based alloy .

[0029] The coil 20 extends around a coil axis Y.

[0030] The coil 20 defines a central seat 200 coaxial with the coil axis Y.

[0031] As observable in Figure 3, according to one embodiment, the coil 20 extends circularly around the coil axis Y, defining an equally circular central seat 200. In other words, both the coil and the central seat have a circular cross-section.

[0032] The driving assembly 2 comprises a fixed core 24 arranged coaxially to the coil 20.

[0033] As shown in Figure 2, according to one embodiment, the fixed core 24 has a substantially cylindrical shape so as to be arranged inside the circular central seat 200. Moreover, the fixed core 24 extends axially between a first contact end 240 and a second interaction end 241. The fixed core 24 is made of a ferromagnetic material to be influenced by the magnetic field generated by the coil 20.

[0034] Moreover, the driving assembly 2 comprises a movable core 22 arranged coaxially to the coil 20.

[0035] As shown in Figure 2 by way of example, the movable core 22 has a substantially cylindrical shape so as to be arranged inside the circular central seat 200. Moreover, the movable core 22 is made of a ferromagnetic material to be influenced by the magnetic field generatedby the coil 20 .

[0036] According to one embodiment , the movable core 22 is axially translatable between a first closing position of the valve seat 100 and a second opening position of the valve seat 100 . In fact , the magnetic field generated by the coil 20 when traversed by the supply current interacts with the ferromagnetic material of the movable core , determining its translation along the coil axis Y between a first closing position of the valve seat 100 and a second opening position of the valve seat 100 .

[0037] According to one embodiment , the solenoid valve 900 of the present invention is a "normally closed" solenoid valve , that is , in the absence of a magnetic field generated by the coil 20 , the movable core is pushed against the valve body 1 , causing the valve seat 100 to close . Once the coil is supplied with the supply current , it generates the magnetic field that causes the translation of the movable core 22 towards the fixed core 24 . Therefore , according to this embodiment , the first position of the movable core 22 corresponds to the closing position of the valve seat 100 , while the second position of the movable core 22 corresponds to the opening position of the valve seat 100 .

[0038] The driving assembly 2 comprises an armature 26 made of ferromagnetic material .

[0039] The armature 26 is magnetically coupled to the coil 20 so as to close the lines of force of the magnetic field generated by the coil 20 . In other words , the armature 26 allows the magnetic field lines to be directed onto the movable core 22 and the fixed core 24 present inside the central seat 200 .

[0040] The armature 26 comprises a head portion 260 extending in a direction substantially transverse to the coil axis Y . Moreover, the armature 26 comprises a side portion 262 extending in a direction substantial ly parallel to the coil axis Y . The armature 26 also comprises a base portion 264 extending in a direction substantially transverse to the coil axis Y opposite to the head portion 260 . In other words , as shown by way of example in Figure 2 , the armature 26 has a "C" shape in which the base portion and the head portion are parallel to one another and connected by the side portion which, consequently, is perpendicular to said base and head portions .

[0041] According to one embodiment , said base portion 264 is operatively coupled to the valve body 1 .

[0042] According to one embodiment , an axial through opening 2640 is obtained in the base portion 264 . According to said embodiment , the movable core 22 is partially housed and sliding in the axial through opening 2640 .

[0043] The driving assembly 2 further comprises a polarexpansion 266 surrounding the movable core 22 so as to increase the interface surface between the movable core 22 and the flux lines of the magnetic field .

[0044] According to one aspect of the invention, the polar expansion 266 is made in one piece in a single body with the base portion 264 of the armature 26 . In other words , the polar expansion 266 is integrated in the base portion 264 of the armature 26 , thus obtaining a single body .

[0045] According to a preferred embodiment , the polar expansion 266 is made in one piece in a single body with the base portion 264 of the armature 26.

[0046] The polar expans ion 266 makes it possible to maximi ze the cylindrical exchange surface of the base portion between the lines of force of the magnetic field and the movable core . Therefore , the polar expansion 266 allows the magnetic field generated by the coil to be optimi zed and, consequently, increases the overall pulling force with which the movable core is engaged to determine the opening of the valve seat 100 .

[0047] The one-piece manufacturing allows a series of advantages to be obtained . Firstly, making the polar expansion in a single body with the base portion signi ficantly reduces production time , as the f inished part may be obtained by progressive stamping from a sheetmetal strip. Furthermore, the manufacturing process proves to be easier to perform, with a significant reduction also in production costs.

[0048] Secondly, the one-piece manufacturing of the polar expansion allows discontinuity surfaces to be eliminated, which would be created if the base portion and the polar expansion were, for example, joined by welding. The elimination of discontinuity surfaces also provides advantages in terms of maximizing the effect of the magnetic field generated by the coil, since said discontinuity surfaces would cause a deviation of the magnetic field lines, resulting in dispersion and consequent loss of efficiency of the solenoid valve, as the movement of the movable core within the coil would be altered .

[0049] Moreover, the process of manufacturing the polar expansion in a single body with the base portion allows the sealing system of the solenoid valve to be significantly simplified.

[0050] Figures la and lb show a solenoid valve of the known art in which the sealing system involving the coil consists of three sealing rings 3310, 3312, 3314 or gaskets. The first sealing ring 3310 allows the polar expansion 3266 to be sealingly coupled to the valve body 3001, the second sealing ring allows the polar expansion3266 and the bobbin 3210 to be sealingly coupled, and the third sealing ring 3314 allows the fixed core 3024 to be sealingly coupled to the bobbin 3210.

[0051] Therefore, making the polar expansion in a single body with the base portion makes it possible to reduce the number of sealing rings, switching from a system with three sealing rings to a system with two sealing rings, as will be described in detail below. Reducing the areas subject to possible leaks means significantly increasing the efficiency and performance of the solenoid valve, as the pressure created inside the solenoid valve remains substantially constant and the translation of the movable core is not altered.

[0052] Moreover, the reduction in the number of sealing rings used in the solenoid valve also makes it possible to improve the contact between the head portion of the armature and the fixed core.

[0053] According to one embodiment, the head portion 260 is placed in direct contact with the first contact end 240 of the fixed core 24 in such a way that the distance between the head portion 260 and the fixed core 24 is substantially zero, i.e., the distance is reduced to the minimum possible distance obtainable by placing in contact two surfaces of two different bodies made of the same material. A substantially zero distance is necessary forcorrect operation of the solenoid valve . In particular, minimi zing the distance between the head portion of the armature and the fixed core makes it possible to increase the pulling force . Conversely, for example , a distance in the order of 0 . 05-0 . 1 mm causes a 40% decrease in the pulling force compared to the condition of correct contact , i . e . , the condition in which the distance between the armature and the fixed core is substantially zero . In fact , this technical feature of a substantially zero distance is achievable as a result of the elimination of one sealing ring from the sealing system, as described above .

[0054] According to one embodiment shown by way of example in Figure 6 , the polar expansion 266 has a polar expansion end 2660 which fits at least partially into the valve body cavity 10 obtained in the valve body 1 around the valve seat 100 . According to said embodiment , the cylindrical side surface 12 that laterally delimits the valve body cavity 10 and the polar expansion end 2660 together form an annular seat 300 in which a first sealing ring 310 is housed . Therefore , the first sealing ring 310 enables the valve body 1 and the armature 26 to be sealingly coupled .

[0055] According to one embodiment , the driving assembly 2 comprises a hollow tubular element 268 arranged coaxially in the central seat 200 so as to accommodate atleast the movable core 22 . Preferably, the tubular element 268 has a substantially cylindrical shape so as to be arranged coaxially in the central seat . In other words , the tubular element 268 is coupled to the central seat 200 by means of a form coupling so that said tubular element 268 is in contact with the spool on which the wire forming the coil 20 is wound . Therefore , the tubular element 268 is interposed between the coil spool and the movable core 22 , allowing better translation of the movable core 22 .

[0056] In fact , the tubular element 268 allows the ef fect of the magnetic field to be optimi zed for moving the movable core of the solenoid valve . Furthermore, the tubular element contributes to the pneumatic sealing ef fect together with the sealing rings that make up the sealing system of the solenoid valve .

[0057] According to one embodiment , the tubular element 268 has a tubular element base 2680 extending between the polar expansion 266 and the valve body 1 . Preferably, the tubular element base 2680 extends radially to the coil axis Y towards and near the cylindrical side surface 12 .

[0058] According to said embodiment shown by way of example in Figure 6 , the tubular element base 2680 , the cylindrical side surface 12 , and the polar expansion end 2660 together form an annular seat 300 in which the first sealing ring 310 is housed . Therefore , according to saidembodiment, the first sealing ring 310 enables the valve body 1, the tubular element 268 and the armature 26 to be sealingly coupled.

[0059] According to one embodiment, the polar expansion end 2660 has a substantially f rustoconical shape. Therefore, according to said embodiment, the first sealing ring 310 engages the f rustoconical side surface of the polar expansion end 2660.

[0060] According to one embodiment, an elastic element 220 is housed in the movable core 22, which engages the fixed core 24 at the second interaction end 241 so as to elastically maintain the movable core 22 in the closing position .

[0061] According to a preferred embodiment, the elastic element 220 is a cylindrical spring. The cylindrical spring, unlike, for example, a conical spring, has a greater axial encumbrance that makes the pushing action of the movable core against the fixed core more effective when the solenoid valve is in the opening configuration.

[0062] According to one embodiment, the fixed core 24 is sealingly housed in the central seat 200 identified by the coil 20 by means of a second sealing ring 312.

[0063] The solenoid valve according to the present invention makes it possible to reduce the number of sealing rings required for correct operation, namely from threesealing rings in solenoid valves of the prior art to two sealing rings in the solenoid valve according to the present invention . In particular, as can be seen by comparing Figure 4 with Figure lb relating to a solenoid valve of the prior art , the embodiment with the polar expansion integrated in the base portion of the armature allows elimination of the sealing ring present between the polar expansion, not integrated in the base portion, and the bobbin adapted to support the coil . The elimination of this third sealing ring allows the structure and mechanics of the coil to be simpli fied, since , precisely, a sealing ring placed between the spool and the polar expansion is eliminated .

[0064] According to a second embodiment , the fixed core 24 is sealingly housed in the tubular element by means of the second sealing ring 312 .

[0065] Therefore , the introduction of the tubular element improves the translation o f the movable core inside the central seat identi fied by the coil by reducing the frictional force existing between the coil and the movable core . Furthermore , the introduction of the tubular element makes it possible to reduce the number of sealing rings so as to signi ficantly reduce air leaks and, consequently, maintain unchanged the pressure generated inside the solenoid valve .

[0066] Furthermore , the introduction of the tubular element makes it possible to shi ft the seals of the solenoid valve from the coil wound on the bobbin to the ends of the tubular element . In fact , according to the present invention, the first sealing ring is compressed, due to the polar expansion made in one piece with the base portion of the armature , onto the seat of the valve body .

[0067] The solenoid valve according to the invention signi ficantly improves the ef ficiency of the magnetic circuit by making the polar expansion in one piece with the base portion of the armature and consequently reducing both the number of components and the interface surfaces that would otherwise deviate the lines of force of the magnetic field . Therefore , the solenoid valve according to the invention provides greater operating reliability . The reduction in components making up the solenoid valve according to the invention allows a reduction in production and assembly costs .

[0068] The obj ect of the present invention is also an armature 26 for a solenoid valve 900 .

[0069] The armature 900 comprises an armature body made of ferromagnetic material .

[0070] According to one embodiment , the armature body comprises a head portion 260 extending on a first armature plane 500 , a base portion 264 extending on a secondarmature plane 600 parallel to the first armature plane 500, and at least one side portion 262 extending between the head portion 260 and the base portion 264 on a third armature plane 700 substantially orthogonal to the first armature plane 500 and the second armature plane 600.

[0071] According to a preferred embodiment, the armature body comprises a head portion, a base portion and a side portion forming a "C"-shaped armature.

[0072] According to the present invention, an axial through opening 2640 is obtained in the base portion 264.

[0073] According to the present invention, the base portion 264, around the axial through opening 2640, has a f rustoconical thickening suitable for creating a polar expansion 266.

[0074] According to one embodiment, the polar expansion 266 is made in one piece in a single body with the base portion 264.

[0075] According to one embodiment, the armature body is made in one piece. Preferably, the armature body is made in one piece in a single body.

[0076] The object of the present invention is also a method for manufacturing an armature 26 for a solenoid valve 900 having an armature body made in one piece in a single body.

[0077] The method comprises the following steps:a ) providing a sheet metal 6 having a substantially rectangular shape ; b ) progressively deforming at least one sheet metal portion corresponding to the base portion 264 so as to obtain the f rustoconical thickening suitable for creating the polar expansion 266 ; c ) further deforming the base portion 264 so as to create the axial through opening 2640 ; d) bending the sheet metal 6 so as to define the head portion 260 , the side portion 262 and the base portion 264 .

[0078] According to one embodiment , the deformation step b ) for obtaining the polar expansion 266 is carried out by means of a first punch 2600 . Preferably, the first punch 2600 comprises a female portion 2601 such that the female portion 2601 can be positioned at the base portion 264 of the armature 26 to create the polar expansion 266 .

[0079] According to one embodiment , the step c ) of deforming the base portion to obtain the axial through opening 2640 is carried out by means of a second punch 2700 . Preferably, the second punch 2700 comprises a male portion 2701 such that the male portion 2701 can be positioned at the base portion 264 of the armature 26 to create the axial through opening 2640 .

[0080] According to one embodiment , the step d) ofbending the sheet metal 6 is carried out by means of a bending tool 2800 suitable for giving the armature a "C"- shaped form.

[0081] According to one embodiment, the method for producing an armature comprises the following steps: bl) creating a first bending line defining the base portion; b2) creating a second bending line defining the side portion and the head portion.

[0082] According to a preferred embodiment, the progressive deformation of the sheet metal is carried out by means of a progressive stamping method, that is, a type of stamping that allows each face of the armature necessary for the correct coupling of the solenoid valve to be obtained through a single sequence of steps.

[0083] It is clear that a person skilled in the art, in order to meet contingent requirements, could make modifications to the invention described above, all falling within the scope of protection as defined by the following claims.

Claims

CLAIMS1. A solenoid valve (900) comprising:- a valve body (1) in which pneumatic connections (1000) are obtained and a valve seat (100) , wherein said valve seat (100) alternately puts in fluidic communication at least two of said pneumatic connections;- a driving assembly (2) operatively connected to the valve body (1) and comprising:- a coil (20) to generate a magnetic field, said coil (20) extending about a coil axis (Y) and identifying a central seat (200) coaxial with said coil axis (Y) ;- a movable core (22) , arranged coaxially to the coil (20) , made of a ferromagnetic material to be influenced by said magnetic field, and axially translatable between a first closing position of the valve seat (100) and a second opening position of the valve seat (100) ;- a fixed core (24) , arranged coaxially to the coil (20) , made of a ferromagnetic material to be influenced by said magnetic field;- an armature (26) made of a ferromagnetic material and magnetically coupled to the coil (20) so as to close the lines of force of the magnetic field generated by the coil (20) ; wherein said armature (26) comprises a head portion (260) extending in a direction substantially transverse to thecoil axis (Y) , a side portion (262) extending in a direction substantially parallel to the coil axis (Y) and a base portion (264) extending in a direction substantially transverse to the coil axis (Y) opposite to the head portion (260) , wherein said base portion (264) is operatively coupled to the valve body (1) , an axial through opening (2640) , in which the movable core (22) is partially housed and sliding, being obtained in the base portion (264) ; wherein the driving assembly (2) further comprises a polar expansion (266) surrounding the movable core (22) so as to increase the interface surface between the movable core (22) and the flux lines of the magnetic field, characterized in that the polar expansion (266) is made in one piece in a single body with the base portion (264) of the armature (26) .

2. Solenoid valve (900) according to claim 1, wherein the polar expansion (266) has a polar expansion end (2660) which fits at least partially into a substantially cylindrical valve body cavity (10) obtained in the valve body (1) around the valve seat (100) , said valve body cavity (10) being internally delimited by a cylindrical side surface (12) , and so that said cylindrical side surface (12) and polar expansion end (2660) form together an annular seat (300)in which a first sealing ring (310) is housed.

3. Solenoid valve (900) according to claim 1 or 2, wherein the fixed core (24) is sealingly housed in the central seat (200) identified by the coil (20) by means of a second sealing ring (312) .

4. Solenoid valve (900) according to any one of claims 1 or 2, wherein the driving assembly (2) comprises a hollow tubular element (268) arranged coaxially in the central seat (200) so as to accommodate at least the movable core (22) , wherein the tubular element (268) has a tubular element base (2680) extending between the polar expansion (266) and the valve body (1) .

5. Solenoid valve (900) according to claim 4 when dependent on claim 2, wherein the tubular element base (2680) forms, together with the cylindrical side surface (12) and the polar expansion end (2660) , the annular seat (300) in which a first sealing ring (310) is housed.

6. Solenoid valve (900) according to any one of claims 2- 5, wherein the polar expansion end (2660) is substantially f rustoconical in shape, and wherein the first sealing ring (310) engages the f rustoconical side surface of the polar expansion end (2660) .

7. Solenoid valve (900) according to any one of the preceding claims, wherein an elastic member (220) is housed in the movable core (22) , which engages the fixed core(22) so as to elastically maintain the movable core (22) in the closing position.

8. Solenoid valve (900) according to claim 7, wherein said elastic element (220) is a cylindrical spring.

9. Solenoid valve (900) according to any one of claims 4- 8, wherein the fixed core (24) is sealingly housed in the tubular member (268) by means of a second sealing ring (312) .

10. An Armature (26) for a solenoid valve (900) , comprising an armature body made of a ferromagnetic material and comprising :- a head portion (260) extending on a first armature plane (500) ;- a base portion (264) extending on a second armature plane (600) parallel to the first armature plane (500) ;- at least one side portion (262) extending between the head portion (260) and the base portion (264) on a third armature plane (700) substantially orthogonal to the first armature plane (500) and the second armature plane (600) , characterized in that an axial through opening (2640) is obtained in the base portion (264) , and in that the base portion (264) , around the axial through opening (2640) , has a f rustoconical thickening suitable for creating a polar expansion (266) .

11. Armature (26) according to claim 10, wherein thearmature body is obtained in one piece in a single body.

12. A method for manufacturing an armature (26) for a solenoid valve (900) according to claim 11, comprising the steps of: a) providing a sheet metal (6) substantially rectangular in shape; b) progressively deforming at least one sheet metal portion corresponding to the base portion (264) so as to obtain the f rustoconical thickening suitable for creating the polar expansion (266) ; c) further deforming the base portion (264) so as to create the axial through opening (2640) ; d) bending the sheet metal (6) so as to define the head portion (260) , the side portion (262) , and the base portion (264) .

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