EP2198446B1 - Method for producing a contact pin for a fluorescent tube and contact pin for a fluorescent tube - Google Patents

Abstract

The present invention relates to a method for producing a contact pin (01) for use as an electric contact element of a fluorescent tube, wherein the contact pin has a recess (06) extending along the longitudinal axis (05) thereof, wherein a connection wire of the fluorescent tube can be inserted into said recess and can be electrically connected to the contact pin (01), wherein the outer wall of the contact pin (01) has a cylindrical contact region (17) which can be engaged in a base bracket of the fluorescent tube in order to establish an electrical contact between the base bracket and the fluorescent tube, and wherein the outer wall of the contact pin (01) has an annular collar (08) with which the contact pin rests against the wall (04) of an end cap (02) when inserted into a recess of the end cap (02) which is provided on the axial end of the fluorescent tube.

Description

The invention relates to a method for producing a contact pin for use as an electrical contact element on a fluorescent tube according to the preamble of claim 1.

Furthermore, the invention relates to a contact pin, as can be produced in particular by the method according to the invention.

Known fluorescent tubes have end caps on their axial ends, on each of which two contact pins are provided. These contact pins serve as electrical contact elements, with which the fluorescent tube is fixed in base receptacles and electrically contacted. In the case of the generic contact pins, a recess is provided along the longitudinal axis, in each of which a connecting wire of the fluorescent tube, through which the fluorescent tube is supplied with electrical voltage, can be inserted. The lead wire is electrically contacted after insertion into the recess of the contact pin with the contact pin, which can be done in particular by Ankrempeln. The outer wall of the contact pin has a cylindrical contact area, which at startup of the fluorescent tube is electrically contacted in the base socket. Further, an annular collar is provided on the outer wall of the contact pin, which projects beyond the cylindrical Kotaktbereich. This collar serves as a positive stop to allow the assembly and fixation of the contact pin in the end cap in a simple manner. The end cap has a recess for each contact pin whose diameter is slightly larger than the diameter of the cylindrical contact region of the contact pin. When mounting the contact pin, the contact pin is inserted with one end in the recess of the end cap until the molded collar comes to rest on the end cap.

To produce the known contact pins, a semi-finished metal product is used, which is made of a brass material. The generic contact pins is a mass-produced small part, so that large quantities must be produced within a very short time. The use of brass as a starting material for the production of the contact pins, however, the maximum achievable production speed is limited, since brass can be processed with known manufacturing processes only with a limited production speed.

The object of the present invention is therefore to propose a new method for the production of contact pins for use on fluorescent tubes, with which the production speed can be further increased. It is another object of the present invention to propose a new contact pin, which can be produced in particular with the new method at the highest production speeds.

These objects are achieved by a method and by a contact pin according to the teaching of the two independent main claims.

Advantageous embodiments of the invention are the subject of the dependent claims.

The inventive method is based on the basic idea that for the production of the contact pin, a metal semi-finished product is used, which consists of an aluminum alloy. The second essential aspect of the production method according to the invention is that the shaping of the contact pin takes place after the metal semi-finished product has been cut to length in two process sections which are in principle separate. In the first process section, the cut-to-length section of the metal semifinished product is first of all shaped, with the formation of at least the collar projecting beyond the diameter of the cylindrical contact region being formed by the reshaping. By reshaping the metal semi-finished product, it is possible to form the projecting collar to the metal semi-finished, so that can be used as starting material, a metal semi-finished product whose diameter corresponds to the diameter of the cylindrical contact area. A metal removal on the outer circumference of the contact pin can be omitted in this way substantially.

In order to produce the recess in the interior of the contact pin, the contact pin is then machined in a subsequent second process section.

By the combined forming and machining of the metal semi-finished product made of an aluminum alloy extremely high production speeds can be achieved. In addition, contact pins of the highest quality can be produced with very good electrical properties by the method according to the invention. As a semi-finished metal product, it is particularly advantageous if a wire is used, since wires with correspondingly well-tolerated diameters are available at low cost. In addition, the substantially endless wire blanket enables quasi-continuous processing and manufacture of the contact pins.

Which forming method for producing the projecting collar on the outer circumference of the contact pin is used, is basically arbitrary. Cold forming processes have proven to be particularly suitable. In particular, the upsetting of the cut-to-size metal semi-finished product is very well suited to form the projecting collar.

In order to ensure good post-processability of the contact pin during assembly on the end cap or when contacting the base socket, the projecting collar should preferably be formed on one side with a conical flank and on the opposite side with a flat flank or with a second conical flank become. The flat edge ensures a secure fit of the contact pin when the federal government abuts against the wall of the end cap.

In order to avoid twisting the contact pins relative to the end cap, whereby the contact wires of the fluorescent tube could be turned off, form and frictional connection between the flat edge of the collar on the contact pin and the opposite wall of the end cap should exist. To ensure this, in a simple manner by the forming process protruding teeth can be formed on the flat edge of the federal government. Since the formation of the protruding teeth takes place during the forming of the aluminum alloy material, no significant additional costs are caused thereby.

The removed by the cutting removal of semi-finished metal material can only be used as metal scrap and is therefore almost worthless. In order to reduce the amount of this resulting from the machining span chip, according to a preferred variant of the method, a portion of the recess can not be produced by machining, but by forming. That is, in the context of the production stage for forming the metal semi-finished product not only the projecting collar is formed on the outside of the cut-to-size metal semi-finished, but also at least a portion of the recess extending in the interior along the longitudinal axis of the contact pin generated by material flow. In particular, by counterfluxing one or two wells can be made reshaping on the front sides of the initially solid metal semi-finished product.

In order to achieve the desired production performance, a drilling should be made after completion of the forming of the metal semi-finished product for the production of the recess. The drilling allows a very high production capacity, in particular when drilling at a speed of more than 10,000 rpm, for example at a speed of 12,800 rpm. During machining, the material should be cooled and lubricated with a lubricant, especially with a nano-lubricant.

In order to ensure that the bore extends exactly along the longitudinal axis of the contact pin and that the drill does not migrate laterally during drilling, it is particularly advisable to drill the recesses starting from both end faces. The hole can be mounted in stages. In other words, this means that the hole is gradually expanded by using drills of ever larger diameters.

In order to simply insert the connecting wire of the fluorescent tube in the recess, a particularly large diameter of the recess is desirable. Conversely, it is advantageous if the recess in the region of the contact between the contact pin and connecting wire has the smallest possible diameter, since then already a very small deformation or deformation is sufficient to produce the electrical contact between the connecting wire and pin. In order to realize both requirements for a contact pin, the one bore should have a larger diameter from an axial end of the contact pin than the bore extending from the opposite end face. As a result, a recess is thus created in the contact pin, which has a region with a larger diameter and a region with a smaller diameter. The area with the larger diameter points to the fluorescent tube after mounting on the fluorescent tube and thus allows easier insertion of the connecting wire. The smaller diameter portion faces away from the fluorescent tube and serves to contact the terminal wire in the contact pin.

To ensure easy insertion of the lead wire from the larger diameter section to the smaller diameter section, a tapered transition section with a drill bit should be drilled between the two cylindrical holes. At the tapered inner wall of this transition region can then be the end of the lead wire from the bore of larger diameter in the area of the bore of smaller diameter out.

The geometry of the conical transition region between the two bore sections is basically arbitrary. Particularly suitable is an opening angle of 60 ° has been found, so that for its production a drill bit with a bevel of 60 ° opening angle should be used.

In order to be able to fix the contact pin to the end cap in a simple manner, the bore with the larger diameter should form a wall thickness in the region of the one axial end of the contact pin, which can be reshaped, in particular folded over. For mounting the contact pin on the end cap, this axial end is then inserted into the recess of the end cap and pushed so far until the projecting collar comes to rest on the wall of the end cap. Subsequently, the protruding on the inside of the end cap end of the contact pin is formed, for example, riveted and thereby fixed the contact pin on the end cap. As far as the outer edges of the contact pin to be chamfered, for example, to avoid injury to the user or to facilitate assembly by insertion, these outer edges should be chamfered by machining in the machining stage.

In order to be able to optimally exploit the potentials of the method according to the invention, in particular with regard to a high production capacity in which, for example, a unit performance of 135 to 155 pieces / min is required, an optimally adapted to the requirements of the manufacturing process material must be used. This material must also meet the requirements for electrical conductivity and mechanical stability. In order to achieve optimum production performance, extensive tests were carried out with a wide variety of aluminum alloy materials. Among other things, materials were used in accordance with the Specification A199.5 (AW 1050), AlMn1 (AW 3103), AlZn5.5 MgCu (AW 7075) and similar aluminum alloys investigated. The various materials studied could not fully meet the required profile of requirements.

The investigations have shown that optimum production conditions and an optimal compromise in terms of material costs, electrical properties and mechanical properties are achieved by using aluminum alloys, in particular aluminum wrought alloys, provided that these aluminum alloys have a minimum content of 90% aluminum and a Minimum content of 4.5% copper and / or a minimum content of 0.5% magnesium. These specifications can be met in particular by aluminum wrought alloys from the 2000 series (Al-Cu) or by aluminum wrought alloys from the 5000 series (Al-Mg) or by aluminum wrought alloys from the 6000 series (Al-Mg-Si) Material contents in percent, these are in percentages by weight.

The aluminum content of the aluminum alloy should preferably be in the range of 93% to 94%. The copper content, in turn, should preferably be in the range of 5% to 6%, in particular in the range of 5.4% to 5.6%.

An even further improvement in the machinability of the aluminum alloy material in the two-stage processing with a forming step and a Zerspanstufe is achieved when the aluminum alloy additionally contains bismuth. Bismuth material is sometimes referred to as bismuth.

The bismuth content should be in the range between 0.1% to 0.9%, in particular in the range between 0.2% to 0.6%. Best results are achieved with a bismuth content of 0.45% to 0.55%.

As part of the material trials, an aluminum alloy was identified as particularly suitable, the quality of which corresponds to the material designation AlCu6Bi.

Furthermore, the aluminum alloy should preferably also have a lead content. The lead content should preferably be in the range between 0.2% to 0.6%, in particular in the range between 0.2% and 0.4%.

Insofar as the aluminum alloy of aluminum, copper and bismuth additionally contains lead, the aluminum alloy should conform to a quality according to the material designation AlCu6BiPb. In addition to the specified ingredients (aluminum, copper, bismuth, lead), the aluminum alloy may also contain traces of silicon, iron, manganese, magnesium, chromium, zinc and / or titanium.

Of the aluminum wrought alloys from the 2000 series (Al-Cu), in particular the aluminum alloy according to the quality of the material number EN AW 2011 is outstandingly suitable for producing the contact pins with the method according to the invention. The quality EN AW 2011 contains, for example, 5.5% copper, 0.48% bismuth, 0.51% lead, 0.06% silicon, 0.13% iron, 0.01% manganese, 0.01% magnesium, 0.01% chromium, 0.03% zinc and 0.03% titanium. The rest of the aluminum alloy is made of aluminum. The aluminum alloy according to the material number EN AW 2011 is also described in detail in the Euro standard EN 573-3. Also well suited is the aluminum alloy according to the material number EN AW 2011 A with the slightly lower minimum copper content of 4.5%.

Alternatively, aluminum 5000 series alloys (Al-Mg) are aluminum alloys according to the material numbers EN AW 5019 (AlMg5) or EN AW 5754 (AlMg3) or EN AW5154A (AlMg3.5 (A)) or EN AW 5083 (AlMg4 , 5Mn0.7) very well suited for the production of the contact pins with the inventive method. Of the aluminum wrought alloys of the series 6000 (Al-Mg-Si), the aluminum alloy according to the material number EN AW 6082 (AlSi1MgMn) is very well suited for the production of the contact pins with the method according to the invention.

Various aspects of the invention are illustrated schematically in the drawings and are exemplified below.

Fig. 1

eine Endkappe zur Anordnung an einem Axialende einer Leuchtstoffröhre mit zwei Kontaktstiften im Querschnitt;

Fig. 2

einen Kontaktstift gemäß Fig. 1 im vergrößerten Querschnitt;

Fig. 3

den Kontaktstift gemäß Fig. 2 in Ansicht von oben;

Fig. 4

den Kontaktstift gemäß Fig. 3 im Schnitt entlang der Schnittli- nie A-A;

Fig. 5

die Herstellung eines Kontaktstifts gemäß Fig. 2 durch Kombi- nation von Umformung und spanender Bearbeitung.

Show it:

Fig. 1

an end cap for mounting on an axial end of a fluorescent tube with two contact pins in cross section;

Fig. 2

a contact pin according to Fig. 1 in enlarged cross-section;

Fig. 3

according to the contact pin Fig. 2 in top view;

Fig. 4

according to the contact pin Fig. 3 in section along section line AA;

Fig. 5

the production of a contact pin according to Fig. 2 through the combination of forming and machining.

Fig. 1 shows in cross-section two contact pins 01 for electrically contacting a fluorescent tube by mounting in a base socket. The two contact pins 01 are made of an aluminum alloy according to the quality described by the material number AW 2011 (Euro standard EN 573-3). To attach the two pins 01 to a fluorescent tube, they are mounted on a cup-shaped end cap 02. The end cap 02, for its part, is pushed onto an axial end of the glass body of the fluorescent tube and fastened there. The end cap 02 is composed of a cylindrical sleeve 03 and an end cap 04, which is made of an electrically insulating material, such as plastic. On the outer wall of the contact pin, a cylindrical contact region 17 is provided which can be brought into engagement in a base socket of the fluorescent tube to produce an electrical contact between socket and fluorescent tube.

The two contact pins 01 each have along their longitudinal axis 05 continuously extending from one axial end to the other axial end recesses 06. In each of these recesses 06, a lead wire of the fluorescent tube is inserted and electrically contacted by crimping the pins 01. The recess 06 has a region 06a with a large diameter, a region 06b with a small diameter and a conical transition region 06c. The connecting wire of the fluorescent tube is pushed through into the area 06b and contacted there electrically.

For fixing the contact pins 01 on the end cap 04, the axial ends 07 facing the fluorescent tube, whose outer and inner diameter initially corresponds to the outer and inner diameter in the region 06a, are riveted. In order to ensure a fixation of the contact pins 01 by the riveting, a collar 08 is also formed on the outer circumference, which comes to rest on the outside of the end cap 04. By the collar 08 and the riveted axial end 07 of the contact pin 01 is positively fixed in the recess of the end cap 04.

Fig. 2 shows the contact pin 01 with the areas 06a, 06b and 06c of the recess 06, with the not yet riveted axial end 07 and the collar 08 in an enlarged view. The collar 08 has a conically shaped edge 09 and a flat shaped edge 10. The flat edge 10 comes to the outside of the end cap 04 to the plant. In the region of the axial end 07 and in the region of the axial end 11, the outer and inner edges are chamfered. The wall thickness of the contact pin 01 in the region of the axial end 07 is just chosen so that the axial end 07 for attaching the contact pin 01 on the end cap 04 can be riveted.

Fig. 3 shows the contact pin 01 with the projecting collar 08 from the direction of the axial end 07. On the flat edge 10 of the collar 08 six protruding teeth 12 are formed, the form-fitting dig when riveting the axial end 07 in the material of the end cap 04 and a rotation of the contact pins 01 prevent. The geometry of the teeth 12 is in accordance with the cross section Fig. 4 seen.

Fig. 5 shows the production of the contact pin 01 in various stages of production. First, in a first stage of a wire material, a portion of predetermined length is cut to length. Subsequently, the cut-to-size metal semi-finished product is cold-formed in one or two stages. When forming the collar 08 is formed so that the material over the outer circumference of the wire, whose outer periphery corresponds to the outer periphery of the contact pin 06 protrudes. In addition, a cup 14 is produced by counter-extrusion in the forming at the axial end 07. The cup 14 forms the first part of the recess 06.

To produce the recess 06 with its areas 06a, 06b and 06c, the semi-finished metal product 13 is subsequently machined in eight stages. In the first three stages of machining bores 15 and 16 are mounted in stages at the axial ends 07 and 11 with fast rotating drills.

After the first three stages for the preparation of the recess 06 through the holes 15 and 16, the axial edges 07 and 11 chamfered or the edges are broken. Subsequently, the bore 15 is deepened in three further stages, each with drills are used with gradually smaller outer diameter. In the last processing stage is then drilled with a drill whose drill tip has a polished section with 60 ° opening angle, the inner contour and thereby formed the conical transition region 06c through the drill bit.

LIST OF REFERENCE NUMBERS

01

pin

02

endcap

03

shell

04

end cap

05

longitudinal axis

06

recess

07

axial

08

Federation

09

Conical flank

10

Level flank

11

axial

12

tooth

13

Elongated metal semi-finished product

14

bowl

15

drilling

16

drilling

17

cylindrical contact area

Claims (15)

1. Method for producing a contact pin (01) for use as an electric contact element of a fluorescent tube, wherein the contact pin has a recess (06) extending along the longitudinal axis (05) thereof, wherein a connection wire of the fluorescent tube can be inserted into said recess and can be electrically connected to the contact pin (01), wherein the outer wall of the contact pin (01) has a cylindrical contact region (17) which can be engaged in a base bracket of the fluorescent tube in order to establish an electrical contact between the base bracket and the fluorescent tube, and wherein the outer wall of the contact pin (01) has an annular collar (08) with which the contact pin rests against the wall (04) of an end cap (02) when inserted into a recess of the end cap (02) which is provided on the axial end of the fluorescent tube,
   comprising the following method steps of:

   a) cutting to length a semi-finished metal product (13a), in particular a wire, which is composed of an aluminum alloy and which has a diameter corresponding to the diameter of the cylindrical contact region (17),

   b) deforming the cut-to-length semi-finished metal product (13b) for producing the collar protruding beyond the diameter of the cylindrical contact region,

   c) machining the deformed semi-finished metal product (13d-13k) to form the recess (06).
2. Method according to claim 1,
   characterized in that
   the cut-to-length semi-finished metal product (13b) is deformed by means of cold deformation, in particular upsetting, in order to form the protruding collar (08).
3. Method according to claim 1 or 2,
   characterized in that
   the protruding collar (08) is deformed on one side with a conical flank (09) and on the opposite side with a planar flank (10) or else with a second conical flank, wherein the planar flank (10) or the second conical flank rests against the wall (04) of the end cap (02), in particular that protruding teeth (12) are deformed on the planar flank (10) of the collar (08), which engage on the wall (04) of the end cap (02) in a form-fitting and force-fitting manner.
4. Method according to any of claims 1 to 3,
   characterized in that
   prior to the start of the machining process, at least one frontal surface of the semi-finished metal product (13c) is deformed, in particular by means of backward extrusion, in order to create a part of the recess (06) in the form of a cup (14).
5. Method according to any of claims 1 to 4,
   characterized in that
   the deformed semi-finished metal product (13d-13k) for forming the recess (06) is machined by means of drilling, in particular by drilling at a rotational speed of more than 10,000 r/min, wherein in particular the recess (06) is drilled in the form of two separate bores (15, 16) starting from the two frontal surface axial ends (07, 11) of the semi-finished metal product (13d-13k), in particular in a gradual manner.
6. Method according to claim 5,
   characterized in that
   the one bore (15) has a diameter larger than that of the other bore (16), wherein in particular for connecting the two cylindrical bores (15, 16) each having a different diameter, a conical transition zone (06c) is created by drilling with the aid of a drill bit.
7. Method according to any of claims 5 or 6,
   characterized in that
   by means of the bore (15) with the larger diameter, a wall thickness which can be deformed, in particular riveted, for securing the contact pin at the end cap (02), is formed in the region of the one axial end (07) of the contact pin (01).
8. Method according to any of claims 1 to 7,
   characterized in that
   during the machining process, the outer edges of the semi-finished metal product (13g) are chamfered at the frontal surface axial ends (07,11).
9. Contact pin (01) for use as an electric contact element of a fluorescent tube, wherein the contact pin has a recess (06) extending along the longitudinal axis (05) thereof, wherein a connection wire of the fluorescent tube can be inserted into said recess and can be electrically connected to the contact pin (01), wherein the outer wall of the contact pin (01) has a cylindrical contact region (17) which can be engaged in a base bracket of the fluorescent tube in order to establish an electrical contact between the base bracket and the fluorescent tube, and wherein the outer wall of the contact pin (01) has an annular collar (08) with which the contact pin rests against the wall (04) of an end cap (02) when inserted into a recess of the end cap (02) which is provided on the axial end of the fluorescent tube,
   characterized in that
   the contact pin (01) is made of an aluminum alloy, in particular a wrought aluminum alloy, wherein the aluminum alloy has a minimum aluminum (Al) content of 90%, a minimum copper (Cu) content of 4.5% and/or a minimum magnesium (Mg) content of 0.5%.
10. Contact pin according to claim 9,
    characterized in that
    the aluminum alloy has an aluminum content in the range of 93% to 94%, and/or the aluminum alloy has a copper content in the range of 5% to 6%, in particular a copper content in the range of 5.4% to 5.6%.
11. Contact pin according to any of claims 9 or 10,
    characterized in that
    the aluminum alloy contains bismuth (Bi), wherein in particular the aluminum alloy has a bismuth content in the range of 0.1 % to 0.9%, in particular a bismuth content in the range of 0.2% to 0.6%.
12. Contact pin according to any of claims 9 to 11,
    characterized in that
    the aluminum alloy contains lead (Pb), wherein in particular the aluminum alloy has a lead content in the range of 0.2% to 0.6%, in particular a lead content in the range of 0.2 to 0.4%.
13. Contact pin according to claim 12,
    characterized in that
    the aluminum alloy has a quality conforming to material designation AlCu6BiPb.
14. Contact pin according to any of claims 9 to 13,
    characterized in that
    the aluminum alloy contains trace amounts of silicon (Si), in particular in the range of 0.01 % to 0.09%, and/or the aluminum alloy contains trace amounts of iron (Fe), in particular in the range of 0.05% to 0.25%, and/or the aluminum alloy contains trace amounts of manganese (Mn), in particular in the range of 0.05% to 0.15%, and/or the aluminum alloy contains trace amounts of magnesium (Mg), in particular in the range of 0.05% to 0.15%, and/or the aluminum alloy contains trace amounts of chromium (Cr), in particular in the range of 0.0005% to 0.0015%, and/or the aluminum alloy contains trace amounts of zinc (Zn), in particular in the range of 0.001% to 0.005%, and/or the aluminum alloy contains trace amounts of titanium (Ti), in particular in the range of 0.01 % to 0.05%.
15. Contact pin according to any of claims 9 to 14,
    characterized in that
    the aluminum alloy has a quality conforming to material designation EN AW 2011 (AlCu6BiPB) or conforming to material designation EN AW 5019 (AlMg5) or conforming to material designation EN AW 5754 (AlMg3) or conforming to material designation EN AW 6082 (AlSilMgMn) or conforming to material designation EN AW 5154A (AlMg3.5(A)) or conforming to material designation EN AW 5083 (AlMg4.5Mn0.7).

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