DE3107399A1 - Method and device for the production of a two-layer Bourdon tube for pressure and temperature gauges and a Bourdon tube produced by the method - Google Patents

Abstract

The invention relates to a method and a device for the production of a two-layer Bourdon tube for pressure and temperature gauges by winding a spring blank in opposite directions from its middle onto a mandrel. To achieve the object of obtaining an exact spring geometry and of avoiding a point of friction at the intersection of the two spring halves, the invention proposes that, before winding, the spring blank is bent in a Z shape in the middle in the direction of the longest axis of its cross-section to such an extent that the transverse spacing of the mutually parallel parts of the longitudinal axes of the two spring halves corresponds to the spacing of the centre plane of the two spring layers. The spring blank is then aligned relative to the mandrel in such a way that the longitudinal axes of the spring halves are moved outside the winding zone in planes radial to the mandrel. The invention also relates to a two-layer Bourdon tube produced by this method.

Description

109/1 «-4-

company

HOUSES ADMINISTRATION-Ges. m.b.H.

Zimmermühlenweg 21

6370 Oberursel / Ts.

"Method and device for the production of a two-layer Bourdon spring for pressure" and Temperature gauges and process-made Bourdon spring. "

The invention relates to a method for producing a two-layer Bourdon spring for pressure and temperature measurement l.c by goijcn I <inl hjrs winding einos Spring blank from his middle ai's on a winding mandrel.

Such a Bourdon pen consists of two lines or spring halves, which consist of a flattened metal tube, which is usually still with one or more long cracks is provided. Each position is in itself like an Archimedean one Spiral 'formed, the two layers in their center by a helical shape coiled middle part are connected to each other. One end of the Bourdon pen is aligned with a reference point of the meter while the other

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End acts on a measuring mechanism and with a corresponding ' Internal pressure, for example, is able to travel 360 degrees. The number of The turns of each layer can fluctuate; usually three to six • turns. ·

In the case of the known manufacturer, such a method Bourdon spring is a winding mandrel with two disc-shaped ropes leading to the front, in rioron / wiper space the one that is initially square and straight The spring blank is placed on the winding mandrel with its center at a slight incline to the tangent. Then (the blank is wrapped around the winding mandrel, that the two ends move past each other and the winding mandrel from the middle part of the The spring is wrapped in a spiral shape. Here of course, the two spring halves approach the side guides. Then the winding process begins in each case for one layer by means of a sliding shoe which is guided around the winding mandrel and which the Bourdon tube Slightly encompassed at the side.

In Bourdon springs produced in this way, however, are the side edges of the individual turns of each layer by no means exactly in plane-parallel surfaces.

In addition, in a not inconsiderable percentage of Bourdon springs, there is a point of contact and friction at the point where the two halves of the spring cross each other after they have been wrapped around the first time the middle part of the ^{fe -} d or if the Wi ekel process is continued

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is axially compressed after the spring halves Support on the side guides of the winding mandrel while generating the corresponding reaction forces. In this case, the initially helical line-shaped Winding direction can be deflected in a purely tangential winding direction, which is not without it a transverse deformation of the Bourdon tube is possible. The origin of geometric irregularities can be explained by the fact that the transverse deformation extends over more than one turn of each spring half distributed, with also a misalignment of the spring cross-section to the axis of the winding mandrel takes place. These operations are based on the figures 1-3 explained in more detail below. In any case, it shows when rewinding the spring, that this has not undergone any noticeable permanent transverse deformation, but has practically no benefit in diο stretched I aye returns. See the 'leprnetri Irregularities, especially the haul ic Occurring friction point at the crossover point of the two halves of the spring are the cause for inaccurate measurements and therefore for a certain Scrap of measuring instruments. It is particularly disadvantageous that the error in most Case only occurs during the first start-up or during a test run, i.e. after the Bourdon spring has been deformed beyond its full deflection by a corresponding operating pressure.

The invention is therefore based on the object "tin Specify method of the type described above, which zl without cumbersome straightening work

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a geometrically exact Bourdon spring that.an the intersection of the two spring halves none Has friction point.

The object is achieved in the method described at the outset according to the invention by cranking the spring blank in the middle in the direction of the longest axis YY of its cross section in a Z-shape so that the cross distance "d ^{1 of} the mutually parallel parts the longitudinal axes of the two spring halves corresponds to the distance "F" of the central planes of the two spring layers, and that the spring blank is then aligned with the winding mandrel so that the longitudinal axes of the spring halves are moved in planes radial to the winding mandrel until the end of winding.

Due to the bend of the spring blank according to the invention the winding path of the individual spring halves is exactly before the winding process begins fixed or specified, so that there are no more transverse forces or no more transverse deformation during winding required to accomplish the transition from the helical to the tangential course of the Bourclon tube / u. By preforming the spring blank, a defined winding path is achieved, so precisely that the side guides of the winding mandrel can be dispensed with. Consequently there is also no longer any axial upsetting - within the helical course of the Bourdon tube, so that the formation of a point of friction is completely eliminated. The side edges of each

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Layers of the Bourdon spring lie in plane-parallel planes, and an inclination of the spring cross-section within the first turns can no longer be observed. The result is a defined spring characteristic below considerable reduction in scrap. In particular, no more committee is observed that only occurs after Test run occurs. The dimensional deviations of the finished ßourdori feathers are much smaller than after conventional method, so that assembly is also considerably facilitated. On complex straightening work can be fully drawn.

The invention also relates to a two-layer Bourdon spring, which is characterized according to the further invention is that the spring blank is in the middle in the direction of the longest axis of its cross section Z-shaped is bent so that the transverse distance between the parts of the spring halves reaching up to the bend corresponds to the distance between the two spring layers.

Finally, however, the invention also relates to a device to produce the crank. This is characterized by two relative movements Tool jaws with aligned ■ plane-parallel surfaces, - their distance of the thickness "d" of the stretched spring blank, as well as bending mandrels attached to the tool jaws, which essentially fill the gap delimited by the plane-parallel pools and the perpendicular ones run to the gap and are arranged alternately on one and the other tool jaws that when moving the jaws towards each other in the direction of the plane-parallel surfaces, the desired offset of the between the bending mandrels of both jaws and the jaws

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self-inserted spring blank can be produced.

Further advantageous refinements of the subject matter of the invention are contained in the remaining subclaims described.

The state of the art, the inventive method, the Bourdon spring itself and the device required for its manufacture are described below with reference to Figures 1-7 explained in more detail.

Show it :

1 shows a plan view of a winding mandrel and the

Manufacture of a Bourdon spring according to the conventional method Procedure during the wrapping process,

• Fig.2 a perspective side view of the middle Te is a Bourdon pen after partial

Execution of the first wrapping process,. '

Fig. 3 an axial section through a two-layer Bourdon spring, which according to the conventional Method according to Figure 1 has been produced,

Fig. 4 is a plan view of an elongated spring blank according to the embodiment of the invention Kröpf process,

FIG. 5 shows an axial section analogous to FIG. 3, but through a two-ply Bourdon spring made according to the invention,

Fig. 6 is a schematic representation of the processes in the working gap of a Kröpf device and

Fig. 7 a Sei UmicJH ', i <.hl. the Kropl vurr ι t.li Uim <j <j <miiiiI '.

^Fig - ⁶ * ■ "

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-ΙΟΙ η Fig. 1 shows a cylindrical winding mandrel 1 on which two side guides 2 in the form of circular disks are attached. A conventional (stretched) Fedorrohling 3 was placed from the rear at an acute angle to the tangent on the winding mandrel 1 and, starting from the center, slipped around the winding mandrel by 180 degrees on a helical path. From here, the winding process is usually continued in the direction of both ends of the spring blank 3. The initial inclination of the spring blank to the tangent to the winding mandrel 1 can be seen approximately from the dashed line 4. When winding, the outer edges 3a and 3b of the spring blank lie against the radial inner surfaces 2a and Zh of the side guides, which forces a gradual transition from the helical course of the first loop to a tangential course of subsequent loopings. The winding mandrel has at the first contact point of the spring blank for the determination of the initial turn a not shown schraubenlinienfirmiges profile, the width of the spring width and the Ti first ife of the spring thickness .entspricht by ^1, starting from the middle, by two side by about 180 ° gradually against Zero goes.

By supporting the edges 3a and 3b, reaction forces are generated, which the neighboring edges of the spring blank press together at the intersection so that a friction point "x" is formed there. The intersection or the point of friction χ is illustrated in more detail in FIG.

The result of the manufacturing process described above is explained in more detail with reference to FIG. There the two layers L ₁ and L _{2 of} the Bourdon spring are shown, which include a transverse distance G between them. As a result of the pressure exerted on the individual turns and the axial compression of the first turns or wraps, geometric irregularities have arisen which are different

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Express dimensions A and B. It can be seen that the outer edges 3a and 3b of the individual layers L. and Lp lie in the same plane along their entire length, but rather that the inner twists pull you, have irregular misalignments, which can only be partially eliminated by Nachrich't work. In particular, this does not completely eliminate the problems at the point of friction X. All turns of the individual Lciyeri I .. and Lp are consequently also not between two parallel planes, and the imaginary center lines of all turns are not two-dimensional, .but a three-dimensional course, since the longest axes of the spring cross-section are in the center the Bourdon spring is also slightly oblique to the axis a-a

1.5 run. In any case, there is no other explanation for the fact that the Bourdon spring according to FIG has readily visible cranking, what after Course of the individual windings would have been expected.

The spring blank 5 according to the invention according to FIG. 4 is bent in the middle in the direction of the longest axis YY of the spring cross-section in a Z-shape. The extent of the crank is chosen so that the transverse distance G between the parts of the spring halves 5c and 5d reaching up to the crank 6 corresponds to _{the distance between the two spring layers L 1} and L _{2 formed later.} It is the clear distance between the two layers.

With regard to the longitudinal axis 5e of the spring blank 5, shown in phantom in FIG. 4, this can also be expressed in such a way that the transverse distance D of the mutually parallel parts of the longitudinal axes of the two spring halves 5c and 5d corresponds to the distance F of the center planes E. and E _?

the two spring acjen L ₁ and L ,, en Lsprich b. The length of the bend b / w. the Kröpfimg swirikel is chosen so that the edges 5a and 5b do not touch at any point after the winding process and also do not come so close that there is a risk of contact. In the case of a Bourdon spring, the overall dimensions Λ = 15 mm, a width of the finer blank of 6 mm, a distance between the central planes F = 9 mm and a resulting transverse distance (clear dimension) G = 3 mm has a crank angle of 21 degrees or An appropriate complementary angle of 159 degrees has proven to be particularly expedient and advantageous.

After the spring blank 5 with a crank according to FIG is provided, this is then aligned to the winding mandrel so that the parallel parts of the Longitudinal axes 5e of the two spring halves lie in a plane that is radial to the winding mandrel 1 (Fig. 1). In the area the crank 6, the longitudinal axis 5e then also extends at an acute angle to. Tangent to the winding mandrel, so that at the beginning there is a hatched line To set the winding mandrel. But here too, the mutually parallel parts of the longitudinal axis 5e move freely from the beginning to at the end of the winding process in the same planes, radial to the winding mandrel, without any inclination or twisting of the spring cross-section. The profiling of the winding mandrel described above (p. 10, lines 18-23) or correspondingly large lateral guides are used Diameter or the sliding shoes performing the winding process (Page 5, lines 17-20)

The result of the winding process according to the invention is shown in FIG. Outside the crank 6, the edges 5a and 5b of the fully wound Bourdon spring run in exactly radial planes, ie the entire Bourdon spring can be circumscribed by plane-parallel surfaces _{- also with regard to its individual layers L. and L 2.} The distances between the individual turns are largely constant; there is no training point at the crossing point. Unless the Bourdon

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The spring is unrolled more wildly according to FIG. 5, the j original shape of the spring blank according to FIG. |

Figures 6 and 7 show a device for the j

Production of the crank according to FIG. 4. The device = has - two tools that can move relative to each other -

bake, of which one (10) is stationary and the other j

(11) is attached to an I ressenstempel 12. The work '

Jaws 10 and 11 have | facing each other

plane-parallel surfaces 13, 14 that have a \

Include gap 15 (working gap). The distance of the;

plan-parallel surfaces or which corresponds to the gap width ^?

while the thickness d of the elongated spring blank 5 (Fig, 4). j

There are bending mandrels 16, 17, 18, 19 on the tool jaws 10 and 11
fastened, in the form of cylinder pins inserted into end-corresponding holes in the tool jaws.
The bending mandrels essentially bridge the gap 15
(Fig.7). The bending pins 16 and 18 are on the movable tool jaws 11, the bending pins 17 and 19
attached to the stationary tool jaws 10. :

As can be seen from Fig. 6, the bending mandrels are 16-19
arranged alternately on the two tool jaws,
that when moving the jaws towards each other
of the plane-parallel surfaces 13 and 14 the desired
Crank 6 can be produced according to FIG. The one on the side

Distance between the adjacent bending mandrels from each other
is essentially the same and corresponds to dimension H,
which is predetermined by the length of the crank 6.
The cranking process itself proceeds in the following way:

First, the mandrels 16 and 18 are together
with the tool jaw 11 in a raised position,
in which they are drawn in dashed lines. In this position

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a stretched spring blank can be easily Slide it in from the side, which is also indicated by the dashed lines. The successors will be the H iei: odorne 1G and 18 alxjosenkt in the direction of arrows 20, whereby the cranked shape of the spring blank 5 according to FIG results. Due to the narrow design of the gap 15, the spring blank 5 cannot move sideways, for which there is a certain tendency, but will be reliable around the cross-sectional axis of the largest Deformed at the moment of resistance.

In order to produce a clean parallel guidance of the two tool jaws 10 and 11 to one another, there is ¹ on the back of the tool jaw 10 a parallel guide jaw 21.

fk \ M tYY

Claims (3)

■ 2 3. Fe br in γ 1981 - Zap / He Files: 109/18 . Proverbs: · A process for preparing a two-layer Bourdon F_eder for pressure and temperature measuring devices through counter-rotating winding a spring blank from its center on a winding mandrel, characterized in that the spring blank before the start of winding at the center in the direction of the longest axis (yy) to its Querschni tts Z-förrnig so abkröpft that the "D" transverse spacing of the mutually parallel portions are longitudinal axes of the two Fe <'gets hurt ften the distance "F" corresponds to the center side end both · spring layers and that then the spring blank to the mandrel so aligned that the longitudinal axes of the spring halves are moved in planes that are radial to the winding mandrel until the end of winding. 2. The method according to claim 1, characterized gekennze i chnet that the cranking is carried out in der'Weise that the middle part of the K'dorrolil ings at an obtuse angle of 155 to 165 degrees, preferably of about 159 degrees, to the two parallel parts of the spring halves runs. 3. Two-ply Bourdon spring for pressure and temperature measuring devices with spring halves of a spring blank wound in opposite directions from the center, characterized in that the spring blank (5) in the middle (M) in the direction of the longest axis (yy) of its cross section Z -shaped like that EPO COPY 109/18 -2- is offset that the transverse distance (G) of the parts of the spring halves reaching up to the offset (6) (5c, 5d) the clear distance between the two. Spring layers ■ (L., Lp) corresponds. j 5 7.weilagi 4. (according to claim 3, Ge characterized Bourdon ^spring: denotes that the median part of the spring blank (5) at an obtuse angle of 155 to 165 degrees, preferably about 159 degrees, to the two parallel Parts of the spring halves (5c, 5d) runs. 5. Device for producing the crank for the method according to claim 1, characterized by two tool jaws (10, 11) which are movable relative to one another and have plane-parallel surfaces (13, 14) which are directed towards one another and whose spacing is the thickness "d" of the stretched spring blank (5 ), as well as by means of bending mandrels (16,17,18,19) attached to the tool jaws, which essentially fill the gap (15) delimited by the plane-parallel surfaces and which run down to the gap and alternately so on one and the other the other tool jaws are arranged that when moving the jaws to each other in the direction of the plane-parallel surfaces, the desired crank (6) of the between the mandrels (16,17,18,19) of both jaws and the jaws inserted Federroh ings (5) can be produced. 6.Vorrichtung according to claim 5, characterized in that one of the tool jaws (11) e.nen parallel guide jaws (21), the 6 m other tool jaws (10) on the side facing away from the gap (15) Ii i π t.prqre ill. EPO COPY 109/18
-3- 7. Apparatus according to claim 5, characterized in that the bending mandrels (16,17,18,19) are designed as cylinder sections whose Raidus corresponds to the bending radius. -4- EPO COPY g