||Herstellungsverfahren für eine Tellerfeder
||Barnes Group Inc., Bristol, Conn., US
||Labeski, Matthew John, Warren, Pennsylvania 16365, US
||derzeit kein Vertreter bestellt
||AT, BE, CH, DE, DK, ES, FI, FR, GB, GR, IE, IT, LI, LU, MC, NL, PT, SE
|Sprache des Dokument
|EP date of grant
|Veröffentlichungstag im Patentblatt
This application relates to a method of making a Belleville spring.
Springs of the Belleville type have been used for various applications
and constitute circular elements of spring steel having a generally frusto-conical
shape with an inner periphery which is spaced axially from the plane of the outer
spring periphery so that the force applied axially against the spring causes the
inner periphery to move toward the outer periphery to place the spring under compression.
This movement of the frusto-conical spring steel element in an axial direction causes
the spring to generate a restoring force proportional to the applied load, which
restoring force is not uniform over the relatively small movement of a frusto-conical
spring. Belleville springs are used in many applications and are produced by the
millions for a wide variety of mechanical devices, such as transmissions for automobiles,
etc. Since Belleville springs are mass produced components, the reduction in the
overall cost of manufacturing a Belleville spring, even if relatively small, translates
into substantial gross cost savings.
Belleville springs have heretofore been formed by blanking a flat,
washer like, ring from a sheet of plain carbon steel that is normally cold roiled.
After the flat ring of carbon steel is stamped or punched from the steel sheet or
strip, it is pressed formed into a truncated conical shape by applying pressure
through matching dies. The frusto-conical steel element is heated to a relatively
high temperature, approaching 1093,3 °C (2000 °F), and is subsequently quench hardened
to create the spring characteristics in the frusto-conical element. Quench hardening
is often followed by heating and cooling steps to stress relieve the spring, reduce
distortions in the spring, obtain the desired final hardness and to set the spring
into its final shape. This general manufacturing procedure is employed in making
Belleville springs. The manufacture of such springs results in a considerable amount
of scrap material, especially in larger sizes above about a 50,8 mm (2.0 inches)
in diameter for the inner periphery, where the metal content of the Belleville spring
is often 30-50% of the price of the spring itself. Due to stamping of the ring shaped
blank used in forming the Belleville spring from strip steel, the edges of the part
have the normal burrs and shear marks. When the formed component is heat treated,
the edges of the stamped sheet metal blank can become very brittle due to minute
cracks. These cracks must be removed by costly and time consuming procedures, such
as tumbling or grinding, which smooths the edges to increase the fatigue life of
he Belleville spring. Thus, the amount of metal waste, the resulting burrs and stress
cracks in the stamped edges of the spring and other problems experienced in manufacturing
Belleville springs substantially add to the cost of these mass produced springs.
The present invention relates to an improvement in manufacturing of Belleville springs,
which improvement reduces scrap, avoids the deleterious effect of edge imperfections
caused by stamping and heat treating and results in a Belleville spring having the
desired technical parameters or characteristics.
Moreover, the patent GB 1 248 473 discloses load applying springs
engaging a friction clutch. The springs comprise an annular component of sheet spring
metal, one of the radially inner and outer edges of the annular component being
moveable axially relative to the other to engage or disengage to clutch. A method
of producing said spring includes the step of bending a spring metal into a ring
form with the width of the strip extending substantially radially of that ring form.
The ends of the strips are joined together to form a closed ring after the strip
has been bent into the ring form. The spring has a dished shape made by a coning
operation which may be performed after the ends of the strip have been joined together.
Alternatively, the ring form produced by the step of bending the strip of spring
metal has a dished shape imparted to it during the bending step. The ends of the
strip may be joined together by welding or one of the ends of the strip may be formed
with a notch and the other end formed with a tongue which is arranged to mate with
the notch. The two ends being joined together by engaging the tongue and the mating
notch provide a mechanical interlock.
In the brochure entitled Belleville Spring Washers published by Associated
Spring, at pages 71-77, the structure and operation of Belleville springs are described
so that the technology associated with Belleville springs need not be repeated.
US-A-3,259,383 illustrates a particular type of Belleville spring, and US-A-4,039,354
describes the method of making Belleville springs and improvement in that method
involving controlling the carbon in the steel used for stamping and forming Belleville
In accordance with the invention, there is a method of making a Belleville
spring comprising the steps of mechanically coiling a flat strip of hardened spring
steel into a continuous, generally flat circular convolution, wherein the strip
has first and second parallel edges defining the width of the strip. The coiler
produces a coiled convolution of the hardened spring steel strip with a preselected
radius of curvature that is formed around an axially extending center of generation,
wherein the first edge, or periphery of the convolution, has a first radius and
the second edge, or periphery of the convolution, has a second radius. The first
radius being less than the second radius by an amount generally equal to the width
of the coiled spring steel strip. Thus, the strip is coiled into a flat configuration
preparatory to cutting the spring steel strip of the circular convolution to create
a generally flat shaped spring, with first and second free ends joined together
i.e. the free ends are interlocked and/or permanently fixed to each other prior
to the forming operation. These method steps are known from GB-A-1 248 473. The
invention is characterised by heating said flat ring shaped spring on a temperature
of over 426,7°C and simultaneously forming said flat ring shaped spring under axial
pressure to heat set said ring shaped spring into a frusto-conical shape.
After the spring strip has been coiled about a given center of curvature
with a selected radius, the convolutions can overlap each other and be cut to form
the free ends or the free end can be stamped or cut separately. The free ends may
have an interlocking dovetail or some other arrangement, for joining the free ends
into a circular configuration resulting in a Belleville spring. It has been found
that joining of the free ends of the coiled hardened spring steel into a Belleville
spring configuration obtains the characteristics of a typical stamped and heat treated
As an example of a Belleville spring constructed in accordance with
the present invention, a hardened strip of SAE 1074 carbon steel having a thickness
of 1,1mm (.043 inches) and a width of 8,3 mm (.325 inches) was forceably coiled
into a convolution having an inside diameter, or periphery, of 129,3 mm (5.098 inches)
and an outside diameter, or periphery, of 146,0 mm (5.748 inches). This frusto-conical
Belleville spring had dovetailed or interlocking free ends held together. A test
fixture was used to compare this split Belleville spring with a standard continuous
ring Belleville spring. It was found that the characteristics of the example and
a continuous stamped Belleville spring were essentially the same. They both had
a height to thickness ratio of 1,9. The Belleville spring, produced in accordance
with the present invention, was fatigue tested between the heights of 2,1 - 1,2
mm (.083 - .048 inches) for 2.500.000 cycles without failure. The tensile stress
on the outside diameter of the new Belleville spring was approximately 572 MPa (83,000
psi) at a height of 2,1 mm (.083 inches) and 869 MPa (126.000 psi) at a height of
1,2 mm (.048 inches) using standard Belleville design parameters. This test of the
example revealed that a Belleville spring that is frusto-conical in configuration
and has two free ends joined together operates substantially the same as a stamped
Belleville spring which is continuous in configuration.
The present invention is particularly applicable for Belleville springs
which are large in diameter and operate in a low stressed environment. Two arrangements
are employed for practicing the present invention. In one instance, the spring steel
is coiled into a frusto-conical configuration which has overlapping convolutions.
A punches of a die set stamp through these convolutions to form the first and second
free ends of the Belleville spring. Thereafter, the Belleville spring is merely
In accordance with the preferred embodiment of the present invention,
the hardened spring steel is distorted transversely like a snap ring to form the
convolutions. The interlocking elements are then stamped by a die set passing through
the overlapping convolutions, the split ring is joined at its free ends and heat
set under pressure. In both embodiments, the starting spring steel strip, or wire,
is a hard drawn steel strip of oil tempered material with a hardness of at least
43-48 C on the Rockwell C scale. By using a hardened spring steel, the coiler forms
the circular body of the spring in a form having a selected radius. During the heat
setting operation, when the convolution is formed into a frusto-conical shape, the
hardness is reduced by about 5-10 points on the Rockwell C scale. Thus, the resulting
Belleville spring has a hardness of approximately 30-40 C on the Rockwell scale.
The invention will become more apparent from the following description
taken together with the accompanying drawings.
- FIGURE 1 is a pictorial view of a Belleville spring constructed in accordance
with the present invention, showing the free ends with interlocking elements spaced
- FIGURE 2 is a pictorial view, similar to FIGURE 1, showing the Belleville spring
with the free ends interlocked as the spring is assembled for use;
- FIGURE 3 is a cross sectional view of a Belleville spring showing the normal
parameters of a Belleville spring;
- FIGURE 4 is a top plan view of the apparatus and method for forming a Belleville
spring in accordance with the present invention showing the circular convolutions
from a coiler, which convolutions are cut to create free ends;
- FIGURE 5 is a side partial view taken generally along line 5-5 of FIGURE 4;
- FIGURE 6 is an enlarged cross-sectional view taken generally along lines 6-6
of FIGURE 4;
- FIGURE 7 is a top enlarged plan view of the die cutting station illustrated
in FIGURE 4;
- FIGURE 8 is an enlarged portion of the free ends of a Belleville spring constructed
in accordance with the present invention showing the interlocking elements stamped
out by the die cutting station schematically illustrated in FIGURE 7;
- FIGURE 9 is a top plan view of a circular preform with the tree ends interlocked
and having a flat configuration preparatory to heat setting in accordance with an
aspect of the present invention;
- FIGURE 10 is a view of the interlocking elements on the free ends of a Belleville
spring showing an embodiment of the invention wherein the free ends of a spring
at rest have a slight gap preparatory to interlocking as shown in FIGURE 9;
- FIGURE 11 is a cross sectional view of the heat set forming dies with the flat
preform as shown in FIGURE 9 in place for heat setting of the Belleville spring;
- FIGURE 12 is a view similar to FIGURE 11 with the heat set and forming die in
the forming position;
- FIGURE 13 is a graph showing a comparison between the sample discussed above
and a standard Belleville spring;
- FIGURE 14 is a top plan view, similar to FIGURE 4, illustrating an embodiment
not in accordance with the present invention wherein the circular convolutions are
inclined as they issue from the coiler to automatically produce the frusto-conical
configuration of a Belleville spring;
- FIGURE 15 is an enlarged cross sectional view taken generally along line 15-15
of FIGURE 14;
- FIGURE 16-23 are enlarged top views wherein the free ends of a Belleville spring
constructed in accordance with the present invention with several interlocking male
and female configurations;
- FIGURE 24 is a top plan view showing the free ends of a Belleville spring constructed
in accordance with the present invention wherein the free ends are butt welded together;
- FIGURE 25 is a side cross sectional view of the free ends of the Belleville
spring showing schematically, the butt welding procedure;
- FIGURE 26 is an enlarged cross sectional view taken generally along line 26-26
of FIGURE 24; and,
- FIGURE 27 is an enlarged view showing the free ends of a Belleville spring with
an angular gap therebetween, which gap may be used for joining the free ends.
Referring now to the drawings wherein the showings are for the purpose
of illustrating preferred embodiments of the invention only, and not for the purpose
of limiting same, FIGURE 1 illustrates a Belleville spring B, in the form of a circular
body 10 formed from coiled, hardened spring steel strip S having free ends 20, 22
with interlocking or dovetail elements, illustrated as female element 24 and male
element 26. In use of the Belleville spring, the free ends are interlocked or held
together by elements 24, 26 to form the frusto-conical configuration of a Belleville
spring, as shown in FIGURE 2. This spring is used in the same applications of any
Belleville spring. It is not necessary to securely affix the interlocking or dovetail
elements; however, these elements can be fixed by welding, adhesion or otherwise.
When Belleville spring B has been constructed in accordance with the present invention
it has the side profile illustrated in FIGURE 3. The spring B is frusto-conical
in configuration with a circular body 10 formed from hardened spring steel strip
S, which strip has a width w and thickness t. The frusto-conical configuration creates
an inner circular periphery 14, with a diameter a, and an outer circular periphery
12, with a diameter b. The overall height h is from the top of the Belleville spring
to the bottom plane of outer periphery 12. The height H is the basic parameter taken
together with the thickness t, which defines the operating characteristics of Belleville
spring B. In practice, the ratio of h/t is in the general range of 1,4-1,6, which
ratio allows Belleville spring B to operate at substantially constant load between
about 50% deflection up to 100% deflection, i.e. flat.
In FIGURE 4, the method and apparatus for constructing the Belleville
spring B is schematically illustrated. A standard snap ring coiler 30 coils flat
strip S, stored on spool 32 which spool is rotated at 90° to show the supply of
strip S. The strip is curved about radius r in a direction transverse to width w
and perpendicular to thickness t. Strip S is hardened to provide a spring steel
strip. Such hardness, in practice, is approximately 43-48 C on the Rockwell C scale
when SAE 1074 carbon steel is employed as in the previously discussed example. Flat
strip S, which in practice has a width of 8,3 mm (.325 inches) and a thickness of
1,1 mm (.043 inches), is coiled into a circular shape having radius r which in practice
is at least 25,4 mm (1.0 inches). As strip S is passed through snap ring coiler
30 it is deflected transversely into convolution C around a center of curvature
c with a radius r so that the convolutions continue to overlap one over the other
as the strip issues from coiler 30. To form free ends 20, 22, a die cutting station
40 is provided. This station has reciprocal dies that cut both ends 20, 22 simultaneously,
or in succession. As shown in FIGURE 7, die cutting elements 42, 44 are moved downwardly
against body 10, after a small end 50 of strip S has been passed through cutting
station 40. A die 40 having die elements 42, 44 moves downwardly, which action cuts
both the female and male elements of the free ends 20, 22. In that instance, portion
50 is scrap and is formed in each stamping operation. Another arrangement for cutting
the elements 24, 26 involves cutting a single layer of strip S at any given time.
This procedure is shown in FIGURE 5. After the cut has been made by the die elements
42, 44, the previously cut free end 20 coacts with the subsequently cut free end
22. Thereafter, new free end 20 progresses around the convulation C into an overlapping
position as shown in FIGURE 5. Each cut produces the interlocking element at the
end of the circular convolution for coaction with the previously cut end; consequently,
no scrap is produced. The profile for the upper die element 42 and the lower die
element 44 is the shape shown in dotted linea in FIGURE 7. The elements are the
upper and lower die elements shown in FIGURE 5. Use of these die sections could
be employed for cutting simultaneously, as shown in FIGURE 7, or cutting in sequence,
as shown in FIGURE 5. Other stamping procedures could be used to cut the ends of
the convolutions to make a split ring shaped spring. Irrespective of the form of
cutting, the strip S has free ends 20, 22 with interlocking elements 24, 26 as shown
in FIGURE 8.
After the ends 20, 22 have been cut at die station 40, the two ends
are joined as shown in FIGURE 8. This joining action provides a flat coiled blank
or preform 100, as shown in FIGURE 9. In the cutting procedure shown in FIGURE 5,
it is possible to create a spacing or gap 60, as shown in FIGURE 10. This spacing-is
closed when element 26 is moved into interlocking relationship with element 24.
The simultaneous cutting operation shown in FIGURE 7 does not produce gap 60. Gap
60 can be of some value in providing a certain amount of holding tension on the
interlocking action between elements 24, 26.
The flat coiled ring of hardened spring steel is preform 100 shown
in FIGURE 9. This preform is formed into the frusto-conical configuration, as shown
in FIGURES 1 and 2, by a pressure and heat processing schematically illustrated
in FIGURES 11 and 12. Heat set press 110 has a upper platen 112 and a lower platen
114. Electrical sources 120, 122 create energy to heat the platens to the desired
heat set temperature, which temperature is in the range of 426,6 °C - 537,7 °C (800
°F - 1.000 °F). In the example explained in this disclosure, the temperature is
approximately 482,2 °C (900 °F). Upper platen 112 has a die element with a conical
surface 130. In a like manner, lower platen 114 has a die member with a conical
surface 132. The lower die member has an upwardly extending cylindrical boss 134
generally matching inner periphery 14 of blank or preform 100. Boss 134 extends
into cylindrical recess 136, which provide clearance for the boss when platen 112
is moved from the loading position shown in FIGURE 11 to the forming position shown
in FIGURE 12. Preform 100 is formed into a frusto-conical shape, as shown in FIGURE
12, and is held in the forming position for a prolonged time which, in practice,
is in the general range of 1,0 - 2,0 minutes. Blank or preform 100 in its flat condition
has ends 20, 22 interlocked by element 24, 26. After the heat set cycle which employs
a selected temperature and a selected time, platen 112 is shifted upwardly into
the loading position, as shown in FIGURE 11. This results in a frusto-conical Belleville
spring as shown in FIGURES 1 and 2. In this embodiment of the invention, flat hardened
spring steel strip is first formed transversely into convolutions C which are cut
to create the flat interlocked preform 100. This preform is then formed by heat
and pressure into a Belleville spring. In FIGURE 6, edges 150, 152 are contoured
to have a smooth arcuate configuration. Thus, these edges 150, 152 need not be machined
during the manufacturing process to remove surface imperfections.
FIGURE 13 is a graph showing the load characteristics for a Belleville
spring constructed in accordance with the present invention which is illustrated
by the solid line curve of the graph. This curve is compared to the dashed line
curve of the graph, which second curve represents a standard stamped circular Belleville
spring. As can be seen, as overall height H decreases, from 3,3 mm to 1,1 mm (0.130
inches to 0.045 inches), both springs operate substantially in accordance with the
same load characteristics. The example of the invention has an inside diameter of
129,3 mm (5.098 inches) and is formed from a hard-ened spring metal strip with a
width w of 8,3 mm (.325 inches) and a thickness t of 10,9 mm (0.43 inches). These
same dimensional characteristics were employed for the standard Belleville spring
represented by the dashed line curve in FIGURE 13.
Referring now to FIGURES 14 and 15, mechanical snap spring coiler
200 is modified to automatically form the frusto-conical configuration when coiling
hardened spring strip S. The coiled strip S issuing from coiler 200 has a frusto-conical
configuration wherein the diameter a is less than the outer diameter b by an count
substantially less than width w. Cutting station 202 performs the cutting processes
illustrated in FIGURES 5 and 7. In this manner, the coiled strip S is formed into
convolutions C' and cut into circular bodies. The bodies are provided with free
ends having interlocking or dovetailed interlocking elements. In this fashion, the
Belleville spring is manufactured merely by cutting the convolutions into circular
configurations. This procedure avoids the heat set process illustrated in FIGURES
11 and 12. Since there is no heat set operation, coiler 200 distorts strip S transversely
to a greater extent than when only a flat preform 100 is produced. By over distortion,
the configuration springs back toward the original shape to create the desired frusto-conical
configuration of Belleville spring B'. The Belleville spring is still a spring coiled
from a hardened strip. The preferred embodiment using the steps shown in FIGURES
4, 11 ad 12 has been practiced; however, the illustrated second embodiment illustrated
in FIGURES 14-15 will produce a Belleville spring that does not require stamping,
forming, heat treating, etc., as used in the prior art.
Referring now to FIGURES 16-23, free ends 210, 212, with or without
a gap as shown in FIGURE 10, have interlocking structures using matching interlocking
elements or dovetails. In FIGURE 16, interlocking means 220 include a dovetail element
222 fitting into recess element 224. In a similar manner, FIGURE 17 uses interlocking
means 230 with elements 232, 234 and FIGURE 18 shows an interlocking dovetail means
240 with elements 242, 244. In FIGURE 19, the interlocking means 250 includes transversely
extending interlocking elements 252, 254 on free ends 210, 212, respectively. A
similar arrangement using longitudinally spaced dovetails is shown as interlocking
means 260 having elements 262, 264 in FIGURE 20. FIGURES 21-23 include interlocking
means 270, 280, 290, respectively, having interlocking elements 272, 274 and 282
and 284, 292 and 294. In these embodiments, the free ends 210, 212 are cut or stamped
by the die cutting station along generally diagonal lines 276, 286 and 296, respectively.
These interlocking means are permanently fixed together, or are used as merely interlocked
elements. The Belleville spring generally maintains the engaged relationship between
the interlocking means while it is in use. The respective elements could be formed
simultaneously by a single punching or stamping operation by die cutting station
40 or by die cutting station 202 as shown in FIGURE 7.
In FIGURES 24-26 free ends 310, 312 are butt welded together along
line 320. As illustrated in FIGURE 25, the free ends may have a space 322 after
being cut by die cutting station 40 or by die cutting station 202. Clamps 330, 332
capture ends 310, 312 and move these ends together as a power supply 340 applies
current between the ends 310, 312 to butt weld the ends along weld 320. The final
product is shown in the cross sectional view in FIGURE 26.
In FIGURE 27, free ends 350, 352 are butt welded along the diagonal
cut line 354 to form weld 356. Various processes could be provided for fixedly securing
the free ends of the Belleville spring. In practice, the dovetail or interlocking
elements illustrated in FIGURE 9, or the dovetail elements illustrated in FIGURE
16, are preferred. The interlocking means hold the free ends together without subsequent
processing, such as welding or adhesively joining the interlocking elements.
Strip S of the example is purchased material having No. 1 rounded
edges, which edges 150, 152 are shown in FIGURE 6. This hardened spring steel strip
is coiled into the desired convolutions and cut to create the interlocking or dovetail
elements. Blank or preform 100 is then assembled with the interlocking elements
together and formed in a heat set operation under pressure wherein preform 100 is
held between two forming dies. The forming process is conducted at a elevated temperature,
in practice, approximately 482,2 °C (900 °F) for about 1,0 minutes. Approximately
15-30 tons of pressure is applied between platens 112, 114. After the part is heat
set, the hardness of the part is lowered by approximately 2-5 points on the Rockwell
C scale. In forming the dovetail or interlocking elements, the die cutting station
40 or die cutting station 202 is added as a hydraulic cutoff to the outlet of a
standard number W 775 Torin coiler, which coiler is modified to feed wire or strip
S from a coil 32. The Torin coiler is standard equipment for producing snap rings.
Internal cams in the coiler are used to adjust the radius r for convolution C. Other
spring coilers could be used for coiling the flat preform 100, as shown in FIGURE
9 or the frusto-conical convolutions C', as shown in FIGURE 14.
- Verfahren für das Herstellen von Tellerfedern, die Schritte aufweisend:
- (a) mechanisches Wickeln eines flachen Streifens (S) aus gehärtetem Federstahl
zu einer stetigen, im wesentlichen flachen kreisförmigen Windung (C), wobei der
gewickelte Streifen (S) erste und zweite parallele, eine Weite (w) definierende
Kanten (150, 152) aufweist und wobei die gewikkelte Windung (C) aus dem Federstahlstreifen
(S) einen gegebenen Krümmungsradius und ein sich axial erstreckendes Erzeugungszentrum
aufweist, wo die erste Kante (150) einen ersten geformten Radius und die zweite
Kante (152) einen zweiten geformten Radius besitzt, wobei der erste Radius um einen
im wesentlichen zu der Weite (w) der Streifen gleich großen Betrag kleiner
als der zweite Radius ist;
- (b) Durchschneiden des gewickelten Federstahlstreifens (S) der kreisförmigen
Windung (C), um eine im wesentlichen flache ringförmige Feder (B) mit ersten und
zweiten freien Enden (20, 210, 22, 212, 310, 312) zu erzeugen;
- (c) Verbinden der freien Enden (20, 210, 22, 212, 310, 312);
- (d) Erhitzen der flachen ringförmigen Feder (B) auf eine Temperatur von über
426,7 °C (800 F) und gleichzeitiges Formen der flachen ringförmigen Feder (B) unter
axialem Druck, um die ringförmige Feder (B) in eine frustriertkonische Form zu thermofixieren.
- Verfahren nach Anspruch 1, wobei die Temperatur in dem Bereich von 426,7 °C
bis 537,7 °C (800 F bis 1000 F) liegt.
- Verfahren nach einem der Ansprüche 1 oder 2, wobei der Erhitzungsschritt für
eine Zeit von mindestens ungefähr 0,5 Minuten durchgeführt wird.
- Verfahren nach Anspruch 3, wobei die Zeit mindestens ungefähr 1,0 Minuten ist.
- Verfahren nach Anspruch 3, wobei die Zeit in dem Bereich von 1,0 - 2,0 Minuten
- Verfahren nach einem der Ansprüche 1 bis 5, wobei der Federstahl eine Härte
in dem Bereich von ungefähr C43 - 48 auf der Rockwell C-Skala aufweist und der Erhitzungsschritt
die Härte um ungefähr 5 - 10 Punkte auf der Rockwell C-Skala erniedrigt.
- Verfahren nach einem der Ansprüche 1 bis 6, zusätzlich die Schritte aufweisend:
- (d) Bereitstellen der freien Enden (20, 210, 22, 212) mit Verschlußelementen
(24, 26, 220, 230, 240, 250, 260, 270, 280, 290); und
- (e) Verschließen der freien Enden (20, 210, 22, 212) vor dem Formungsschritt.
- Verfahren nach Anspruch 7, wobei die freien Enden (20, 210, 22, 212) einen Spalt
(60) vor dem Verschlußschritt zwischen sich aufweisen.
- Verfahren nach Anspruch 7 oder 8, wobei der Verschlußschritt die freien
Enden (20, 210, 22, 212) permanent verbindet.
- A method of making a Belleville spring comprising the steps of
- (a) mechanically coiling a flat strip (S) of hardened spring steel into a continuous,
generally flat circular convolution (C), said coiled strip (S) having first and
second parallel edges (150, 152) defining a width (w), said coiled convolution (C)
of said spring steel strip (S) having a given radius of curvature and an axially
extending center of generation where said first edge (150) has a first formed radius
and said second edge (152) has a second formed radius, with said first radius being
less than said second radius by an amount generally equal to said width (w) of said
- (b) cutting said coiled spring steel strip (S) of said circular convolution
(C) to create a generally flat ring shaped spring (B) with first and second free
ends (20, 210, 22, 212, 310, 312)
- (c) joining said free ends (20, 210, 22, 212, 310, 312); characterized by
- (d) heating said flat ring shaped spring (B) on a temperature of over 426,7
°C (800 °F) and simultaneously forming said flat ring shaped spring (B) under axial
pressure to heat set said ring shaped spring (B) into a frusto-conical shape.
- The method as defined in claim 1 wherein said temperature is in the range of
426,7 °C to 537,7 °C (800 °F to 1000 °F).
- The method as defined in claim 1 or 2 wherein said heating step is performed
for a time of at least about 0,5 minutes.
- The method as defined in claim 3 wherein said time is at least about 1,0 minutes.
- The method as defined in claim 3 wherein said time is in the range of about
1,0 - 2,0 minutes.
- The method as defined in one of the claims 1 to 5 wherein said spring steel
has a hardness in the range of about C43 - 48 on the Rockwell C scale and said heating
step reduces said hardness by about 5 - 10 points on the Rockwell C scale.
- The method as defined in one of the claims 1 to 6 including the additional steps
- (d) providing said free ends (20, 210, 22, 212) with interlocking elements (24,
26, 220, 230, 240, 250, 260, 270, 280, 290); and
- (e) interlocking said free ends (20, 210, 22, 212) before said forming step.
- The method as defined in claim 7 wherein said free ends (20, 210, 22, 212) have
a gap (60) therebetween before said interlocking step.
- The method as defined in claims 7 or 8 wherein said interlocking step permanently
affixes said free ends (20, 210, 22, 212).
- Procédé de fabrication d'une rondelle Belleville, comprenant les étapes consistant
- a) enrouler mécaniquement une bande plate (S) d'acier à ressort durci, en une
spire circulaire continue généralement plate (C), cette bande enroulée (S) présentant
un premier bord et un second bord parallèles (150, 152) définissant une largeur
(w), la spire enroulée (C) de la bande d'acier à ressort (S) ayant un rayon de courbure
donné et un centre de génération s'étendant axialement, le premier bord (150) présentant
un premier rayon formé et le second bord (152) présentant un second rayon formé,
le premier rayon étant inférieur au second rayon d'une quantité généralement égale
à la largeur (w) de la bande,
- b) découper la bande en acier à ressort enroulée (S), de la spire circulaire
(C), pour créer un ressort de forme annulaire généralement plat (B) ayant une première
extrémité et une seconde extrémité libres (20, 210, 22, 212, 310, 312), et
- c) relier ces extrémités libres (20, 210, 22, 212, 310, 312),
caractérisé en ce qu'
- d) on fait chauffer le ressort de forme annulaire plate (B) à une température
de plus de 426,7°C (800°F) tout en formant simultanément ce ressort de forme annulaire
plate (B) sous une pression axiale pour lui donner une forme tronconique par application
de chaleur de mise en forme.
- Procédé selon la revendication 1,
la température de mise en forme se situe dans la plage de 426.7°C à 537,7°C (800°F
- Procédé selon la revendication 1 ou 2,
l'étape de chauffage est effectuée pendant une durée d'au moins 0,5 minute environ.
- Procédé selon la revendication 3,
la durée est d'au moins 1,0 minute environ.
- Procédé selon la revendication 3,
la durée se situe dans la plage d'environ 1,0 à 2,0 minutes.
- Procédé selon l'une des revendications 1 à 5,
l'acier à ressort a une dureté se situant dans la plage d'environ C43 à C48 sur
l'échelle C de Rockwell, et
l'étape de chauffage réduit cette dureté d'environ 5 à 10 points sur l'échelle
C de Rockwell.
- Procédé selon l'une des revendications 1 à 6, comprenant les étapes supplémentaires
consistant à :
- d) munir les extrémités libres (20, 210, 22, 212) d'éléments d'interverrouillage
(24, 26, 220, 230, 240, 250, 260, 270, 280, 290), et
- e) interverrouiller ces extrémités libres (20, 210, 22, 212) avant l'étape de
mise en forme.
- Procédé selon la revendication 7,
les extrémités libres (20, 210, 22, 212) ont entre elles un intervalle (60) avant
- Procédé selon les revendications 7 ou 8,
l'étape d'interverrouillage fixe les extrémités libres (20, 210, 22, 212) de façon
Patent Zeichnungen (PDF)