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Title:
TOOLING FOR ASSEMBLY A MAGNET TO A RETAINER
Document Type and Number:
WIPO Patent Application WO/2019/203889
Kind Code:
A1
Abstract:
Punch press tooling solves the problem of accurately and efficiently assembling an object in a retainer. In particular, when the retained object is a magnet, proper retainer/magnet alignment and accurate polarity marking on the retainer is achieved. During installation, a pre-assembly of the retainer and magnet is captured between a punch and a push-out pin. As the magnet closely approaches an anvil, opposite poles of the magnet and a magnetic stop attract each other so that the magnet rotates into alignment with the anvil marking bosses before a lip on the retainer is crimped. As a result, polarity marks are imprinted on the top of the lip that correspond to the magnetic poles of the magnet. The same process can be used with other non-magnet objects with any type of markings.

Inventors:
LAKE JENNIFER (US)
PATTON ROGER (US)
BENTRIM BRIAN (US)
ZHANG LARRY (CN)
Application Number:
PCT/US2018/057408
Publication Date:
October 24, 2019
Filing Date:
October 24, 2018
Export Citation:
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Assignee:
PENN ENG & MFG CORP (US)
International Classes:
B21D28/12; B21D19/08; B21D19/10; B21D22/02; B21D22/04; B21D22/08; B21D24/06; B21D28/34; B25B27/20
Foreign References:
US20160368038A12016-12-22
US4615475A1986-10-07
US20060067804A12006-03-30
Attorney, Agent or Firm:
GORE, Gregory J. (US)
Download PDF:
Claims:
Claims

1. Punch press tooling for assembling an object within a retainer, comprising:

a main body adapted for rigid affixation to a framework of the press directly beneath a reciprocal punch, said main body having a main body bore within which an upwardly spring- biased, push-out pin reciprocates between compressed and released positions, said push-out pin having a base plate at a bottom end thereof that is closely received within said the main body bore and an upwardly extending shank terminating at a distal top end;

a compression spring operative between said base plate and an end wall at the bottom of the main body bore;

an anvil plate affixed to the top of the main body, said anvil plate having an aperture concentric with the main body bore through which said shank of the push-out pin extends; and

a sleeve abutting a top side of the anvil plate, said sleeve having a well in axial alignment with said main body bore, said well adapted to receive a pre-assembly of the object and the retainer and to also receive the punch which operates against one side of the retainer, whereby an opposite side of the retainer is pressed downward against the anvil plate while the push-out pin engages the object within the retainer such that a feature on the opposite side of the retainer is deformed to rigidly affix the object to the retainer.

2. The punch press tooling of claim 1, wherein said feature on the retainer is a circumferential lip extending from a top edge of the retainer, which is adapted to partially close a mouth of the retainer against the object.

3. The punch press tooling of claim 1, further including a stop affixed to the main body which abuts the push-out pin base plate when the pin is in the released position to prevent further upward movement of the pin from the released position.

4. The punch press tooling of claim 3, wherein the stop has a central hole through which said shank of said push-out pin passes as said push-out pin moves between its compressed and released positions.

5. The punch press tooling of claim 3, wherein the stop is a magnetic stop which operates to attract said base plate when said push-out pin is moved to the released position.

6. The punch press tooling of claim 5, wherein the object is a magnet loosely contained within the retainer, and said magnetic stop has upward facing north and south magnetic poles that match downward facing north and south magnetic poles of the magnet, wherein the magnet is magnetically brought into opposite polar alignment with the magnetic stop during a downward phase of the punch movement cycle.

7. The punch press tooling of claim 1, wherein the retainer and object are loosely assembled in a pre-assembly, and wherein the pre-assembly is captured between the punch and said push-out pin at all times during an installation stroke of the punch beginning when the punch first contacts the retainer during a downward phase of punch movement cycle, and ending during an upward phase of the punch movement cycle when the punch lifts away from the retainer.

8. The punch press tooling of claim 7, wherein the beginning and ending of the installation stroke correspond to the released position of the push-out pin.

9. The punch press tooling of claim 1, further including at least one raised boss on the anvil plate which imprints markings on the retainer as the object is affixed to the retainer.

10. The punch press tooling of claim 9, wherein the object is a magnet and the markings are polarity markings which correspond to the magnetic poles of the magnet.

11. The punch press tooling of claim 5, wherein the magnetic stop is at least partially located within the aperture of said anvil plate.

12. The punch press tooling of claim 11, wherein the shank of said push-out pin extends through the stop, the aperture of said anvil plate, and the sleeve well.

Description:
Tooling for Assembling a Magnet to a Retainer

Related Applications

[0001] This non-provisional U.S. patent application claims priority to Chinese Patent Appln. No. 201810337766.7 entitled“Tooling for Assembling a Magnet to a Retainer” filed April 16, 2018.

Field of the Invention

[0002] The present invention relates to items fixed within a retainer. More specifically, it relates to magnet assemblies and press tooling for fitting a magnet within a retainer where the polarity of the magnet is aligned in a predetermined orientation as it is installed.

Background

[0003] It is often desirable to fix a magnet to an article such as clothing. One solution is to mount the magnet within a retainer and clinch the retainer to the article. Adhesives are one of the most common methods of fixing the magnet within the retainer. However, the use of adhesives for this purpose has drawbacks. For example, the connection strength between the magnet and retainer is only as strong as the adhesive bond. Similarly, if the magnet is plated, the connection strength is only as strong as the plating bond to the magnet.

[0004] Eliminating the retainer and clinching the magnet directly to an article is generally not possible. Magnets generally cannot be shaped to include a clinch feature and/or do not have the strength to handle the installation force of the clinch process.

[0005] It is well known that the magnitude of the force between a magnet and target is dependent on the square of the distance between the two. Therefore, as the distance between a magnet and its target increases, the connection force between the two reduces exponentially. The design of many current magnet assemblies are undesirable because they leave a gap between the magnet and the retainer’s active surface, which weakens the assembly’s effectiveness.

[0006] U.S. patent 7,772,948 discloses an assembly having a magnet mounted flush within a retainer by forming the retainer around the magnet. This assembly is very expensive to produce and requires a high-force production process, which could damage the magnet.

[0007] Modem magnet structures can have multiple polarities, which require specific installation alignment. Many prior art assemblies do not orient the magnet with the desired polarity alignment.

[0008] Therefore, it would be desirable to provide a magnet assembly in which the retainer holds the magnet flush with the retainer’s active surface, and which is produced using an economical and efficient assembly process without the use of adhesives. It would also be desirable to provide a magnet assembly that orients the magnet in a prescribed polarity alignment and is economic and efficient to produce.

Summary of the Invention

[0009] The invention provides an assembly of an object within a retainer. In one preferred embodiment, the assembly is a clinching or swaging retainer assembly that can hold a magnet flush to a surrounding surface. A closing feature holds the magnet flush to the top, active surface of the retainer. In a preferred embodiment, the closing feature includes a deformable center knob in the counterbore at the bottom of the retainer. In addition to the knob, the secondary part can also be held with an adhesive although it is not necessary.

[00010] Alignment features on the outer portion of the retainer fix the magnet in a desired orientation if necessary. If the part is correlated or is asymmetrical, successive parts can be aligned in the same orientation during assembly. This ensures that the object is always aligned in the same orientation during assembly and installation into the retainer.

[00011] The invention also provides special tooling to accurately assemble the magnet in the retainer. The tooling solves the problem of proper retainer/magnet alignment and accurate polarity marking. As described in more detail below, the retainer and magnet are assembled with a punch press that aligns, assembles and marks the finished product in a single stroke of the punch press. In the pre-assembly, the magnet is loosely held within the retainer. The pre-assembly is placed upside-down (magnet facing downward) in the well of the tooling. As an installation punch advances against the retainer, the pre-assembly is pushed against a tooling anvil, which closes and marks the outer rim of the retainer with polarity indicia. A central spring-biased, push-out pin keeps the pre-assembly securely in the retainer during this process. An alignment magnet located within the tooling underneath the anvil magnetically aligns the magnet just before the retainer is closed upon it. The alignment magnet ensures that the marking made by the anvil is always aligned with the polarity of the magnet. After the assembly stroke of the punch is completed, the punch is withdrawn upward. The push-out spring provides sufficient force to overcome the magnetic attraction between the assembled part and the tooling alignment magnet. Brief Description of the Drawings

[00012] Fig. 1 is a top perspective of a magnet assembly in accordance with a preferred embodiment of the invention;

[00013] Fig. 2 is cross section taken along lines 2-2 of Fig. 1;

[00014] Fig. 3 is a top perspective of installation tooling in accordance with a preferred embodiment of the invention;

[00015] Figs. 4 and 5 are cross sections of the assembly tooling during sequential steps in the production process; and,

[00016] Fig. 6 is a top plan view of the marking/closing anvil and alignment magnet of the tooling shown in isolation.

Detailed Description of the Preferred Embodiments

[00017] A magnet assembly in accordance with a preferred embodiment of the invention is shown in Figs. 1 and 2, and is designated generally by reference numeral 10. In this embodiment, the magnet assembly generally comprises a cylindrical magnet 11 mounted within the internal cavity of a cylindrical retainer 13. The retainer 13 has a bottom 8 and upwardly-extending side walls 9 relative to the direction shown in Figs. 1 and 2. The top of the sidewalls define a mouth of the retainer. A rim 7 extends radially-outwardly from the top of the side walls 9 and a capture lip 17 extends radially-inwardly from the top side of the walls 9. An annular undercut 6 is formed in the outer surface of the side walls 9 proximate and underneath the rim 7.

[00018] Modem magnets can have a variety of magnetic poles and pole arrangements. In the embodiment shown in Fig. 1, the magnet 11 has four upward-facing, radially-alternating north and south poles. To mark the pole locations, the retainer rim 7 has upward-facing indicia 15, which indicate the polarity and location of the pole. The indicia 15 are preferably made during the assembly process of the magnet and retainer.

[00019] Referring to Fig. 2, the capture lip 17 securely holds the magnet 11 in a central counterbore within the body of the retainer 13. In a preferred embodiment, the upper edge of the magnet has a chamfered edge that contacts the lip 17. To compensate for dimensional variations in both the magnet 11 and retainer 13, a deformable knob 12 protrudes axially - upwardly from the bottom 8 of the retainer within the counterbore.

[00020] Tooling in accordance with a preferred embodiment for assembling the magnet 11 and retainer 13 is shown in Fig. 3. The various main elements of the tooling described below have a circular cross section centered on a common axis, and are seated in various sections of a central, irregularly-shaped bore extending through a main body 25. The main body 25 surrounds and supports several working components as better seen in Figs. 4 and 5. The main body 25 can be fixtured in a punch press (not shown).

[00021] With reference to the orientation shown in Figs. 4 and 5, the tooling 30 further includes an upper sleeve 24 enveloping the upper portion of the main body 25. The upper sleeve has a central, axially-extending well 23 that is constructed to receive a pre-assembly, i.e, the magnet assembly after the magnet has been inserted into the counterbore of the retainer but before the lips 17 have been deformed into contact with the chamfered edge of the magnet 11. In this embodiment, the pre-assembly is installed upside-down, i.e., with the magnet facing down and contacting the bottom of the well 23.

[00022] The tooling further includes a push-out pin 27, which reciprocates axially within the main body. The pin 27 has a main cylindrical body 27a with an upper end and a circular base plate 29 fixed to the lower end. In this preferred embodiment, the upper portion of the pin 27 reciprocates through a bore 34 in the anvil 28 (described below) and bottom of the well 23, and the lower end of the pin 27 and base plate 29 reciprocate within a middle counterbore 36 in the main body 25. The middle portion of the body 27a reciprocates through a bore 35 in an alignment magnet 26 (described below). The pin 27 reciprocates between a lower limit or compressed position show in Fig. 4 and an upper limit or released position shown in Fig. 5. In the lower limit position, the upper end of the pin 27 is flush with the bottom of the well 23. In the upper position, the base plate 29 contacts the alignment magnet 26, which acts as a stop against any further upward movement. In the upper position, the upper end of the pin 27 extends upwardly far enough to eject at least a portion of the magnet assembly 10 out of the well 23.

[00023] A compression spring 22 is seated the middle counterbore 36. The spring 22 contacts the base plate 29 and biases the pin 27 upwardly.

[00024] An anvil 28 is fastened to the top of main body 25 with screws 32. The anvil 28 supports the pre-assembly as the lip 17 is bent into contact with the magnet 11.

[00025] An alignment magnet 26 is located intermediate the anvil 28 and the compression spring 22. The alignment magnet 26 sits in another middle counterbore 35 in the main body. Since the magnet fits loosely within the retainer of the pre-assembly, the alignment magnet aligns the magnet within the retainer 13 with a predetermined polarity alignment before the lip is bent into contact with the magnet 11.

[00026] In the tooling shown in Fig. 3, a pre-assembly has been placed upside-down (relative to Figure 1) into the well 23 of the sleeve 24. This position corresponds to Fig. 4.

[00027] A method of assembling the magnet 11 and retainer 13 in accordance with a preferred embodiment is illustrated in Figs. 4 and 5. The method comprises a simple, two- step process using the above-described tooling 30. Using this method, the retainer 13 holds the magnet 11 flush with the retainer’s active surface, and orients the magnet 11 in a prescribed polarity alignment.

[00028] Initially, the pre-assembly is placed in the well 23 of the sleeve 24 with the top face of the magnet 11 resting on the top end of the pushout pin 27. An anvil 21 is then lowered into contact with the bottom of the retainer 13. The pre-assembly is gripped between the punch 21 and the push-out pin 27 throughout the assembly process.

[00029] Next, the punch 21 moves downward and applies a force to the bottom of the retainer 13 as shown in Fig. 4. The punch 21 proceeds downwardly toward the anvil 28 against the force of the push-out pin 27. Just before the pre-assembly approaches the anvil, 28, the alignment magnet 26 exerts a magnetic force on the assembly magnet 11 and aligns (rotates) it into the predetermined polarity alignment. Upon impact with the anvil 28, the capture lip 17 around the top of the retainer is closed (deflected) down against the magnet 11 to securely capture it within the retainer as seen in Fig. 2. At the same time, polarity indicia 15 are simultaneously stamped in the retainer rim 7 by marking bosses 30 on the anvil 28 as seen in Fig. 6. Thus, using this process, the magnet 11 and retainer 13 are assembled and marked in a single stroke of the press punch 21.

[00030] The punch 21 is then withdrawn upwardly. Even though the punch moves upwardly, the spring 22 continues to exert an upward force on the assembly 10 to hold the assembly 10 captive between the end of the punch 21 and the push-out pin 27. Once the punch 21 fully withdraws from the tooling as seen in Fig. 5, the assembly 10 is returned to a home position where the push-out pin 27 stops. As the pin 27 approaches the home position, the base plate 29 of the pin is magnetically attracted upwardly and held against the alignment magnet 26. This magnetic attraction provides a reliable stop for consistently discharging the assembly 10 from the top of the well 23. The upward magnetic attraction on the base plate 29 by the alignment magnet 26 also accommodates a greater tolerance for the spring length and tension. The alignment magnet 26 therefore provides two functions, namely, magnet alignment and ejection assistance of the completed assembly 10. After the assembly process is completed, the assembly 10 is removed and the next pre-assembly is placed in the well 23 against the push-out pin. The assembly process can then be repeated.

[00031] The anvil 28 and alignment magnet 26 are shown in isolation from above in Fig. 6 for a more complete understanding of the tooling. The anvil 28 is secured to the body of the tooling by screws 32. In the embodiment of Figs. 3-5, the anvil 28 has four raised embossing features 30, which stamp the rim 7 of the retainer 13 with polarity markings as seen in Fig. 1. Referring to Fig. 6, the north and south polarity indicia of the anvil bosses 30 are opposite to the alignment magnet poles (as shown in dotted lines). This arrangement will therefore attract opposite poles of the magnet 11 in the retainer 13 just before the parts are secured. Thus, the magnet 11 will always be radially aligned in polarity with the markings that will occur on the retainer rim of the assembly 10.

[00032] The foregoing description is to be considered illustrative only of the principles and possible embodiments of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described. Accordingly, suitable modifications and equivalents may be resorted to, all falling within the scope of the invention which shall be determined only by the following claims and their legal

equivalents.