The present invention is explained in greater detail in the following on the basis of multiple exemplary embodiments of a flared screw fitting which are illustrated in the drawing.
FIG. 1 shows an arrayed illustration of a connecting piece having union nut, a flared pipe end, and a union screw,
FIG. 2 shows a flared screw fitting made of the components in FIG. 1 in the hand-tight pre-mounted state,
FIG. 2
a shows a detail enlargement of FIG. 2 in the area of the tulip flare,
FIG. 3 is like FIG. 2, but in the final mounted state,
FIG. 3
a is like FIG. 2a, but in the final mounted state,
FIG. 4 is like FIG. 3, but having an alternatively shaped union screw,
FIG. 4
a is like FIG. 3a, but having an alternatively shaped union screw,
FIG. 5 is like FIG. 3, but having another alternatively shaped union screw,
FIG. 5
a is like FIG. 3a, but having another alternatively shaped union screw,
FIG. 6 shows a flared screw fitting having a connecting piece having external thread and a union nut, which works together therewith, having a transmission ring in the final mounted state of the screw fitting,
FIG. 6
a shows a detail enlargement from FIG. 6 in the area of the tulip flare.
FIG. 1 shows a flared screw fitting 1 according to the present invention, in which the individual components are illustrated arrayed neighboring one another for the sake of clarity. The flared screw fitting 1 comprises a connecting piece 2, a pipe 3, of which only a short end section is shown, and a union screw 4. The connecting piece 2 has an external threaded section 5 on its end shown on the left in the figure, adjoining a hexagon 6, and also a union nut 7 having an internal threaded section 8. This internal threaded section 8 is compatible with an external threaded section 9 of the union screw 4, which also has a hexagon 10 like the connecting piece 2.
One end of the pipe 3 is reshaped (flared) to form a tulip flare 11. The tulip flare 11 has a conical shape and originates from the non-deformed remainder of the pipe 3, whose external diameter is slightly smaller than the internal diameter of the through hole 12 of the union screw 4, so that the union screw 4 is displaceable on the pipe 3. The union nut 7 of the connecting piece 2 is implemented as a so-called “wire nut”, an annular, peripheral wire section 13 which is inserted later having half of its cross-section inserted into a semicircular groove in the connecting piece 2 and half inserted into an also semicircular groove in the union nut 7 and thus forming a connection fixed against an axial load, in which the ability of the union nut 7 to rotate in relation to the remaining connecting piece 2 is maintained.
In FIG. 2, the pipe connection is set in the so-called pre-mounted state. For this purpose, the union nut 7 is screwed onto the union screw 4 until no further mounting progress is achievable with the aid of the torque applicable by hand. It may be seen from the enlargement in FIG. 2a that an internal mantle surface 14 of the tulip flare 11 presses against a stop face 15 of the connecting piece 7. The cone angle of the stop face 15 on one side is slightly smaller in practice than the cone angle of the mantle surface 14 on the other side, so that in any case a contact is achieved externally on the stop face 15. A sealing ring 17, which is circular in cross-section in its unloaded starting state (see FIG. 1), inserted into a groove 16 having a triangular cross-section, has already assumed a rounded triangular shape in the pre-mounted state because of the slight pressure which is exerted by the external mantle surface 14 of the tulip flare 11.
The embodiment according to the present invention particularly comprises the internal mantle surface 18 of the union screw 4 only contacting the external mantle surface 19 of the tulip flare 11 in an area 20 whose smallest diameter 21 is larger than the smallest diameter of the stop face 22 of the connecting piece 7 and/or the largest diameter of the groove 16, i.e., the diameter of the groove edge facing toward the stop face 15. The special contacting conditions may also be recognized very clearly on the basis of the gap 23 existing between the internal mantle surface 18 of the union nut 4 and the external mantle surface 19 of the tulip flare 11, which increases continuously toward the outlet of the tulip flare. The gap results from cone angles of the external mantle surface 19 of the tulip flare 11 on one side and the internal mantle surface 18 of the union screw 4 on the other side which deviate slightly from one another. The angle difference is approximately 1°, but depending on the circumstances of the individual case (diameter of the screw fitting, materials, wall thicknesses of the pipe) may also be up to a few degrees. FIG. 3 shows the pipe connection 1 in the final mounted state. As may be seen from FIG. 3a, the final mounted state is achieved when the union screw 4 is in contact over the entire length 24 of its internal mantle surface 18 with the external mantle surface 19 of the tulip flare 11. As a result of further rotation of the union nut 7—starting from the hand-tight pre-mounted state—the union screw digs in in the forward area 20, which was solely in contact with the external mantle surface 19 of the tulip flare 11 in the hand-tight pre-mounted state. It is important that even in the final mounted state, the orientation of the internal mantle surface 14 of the tulip flare remains essentially unchanged, in particular that the gap 25 between the internal mantle surface 14 of the tulip flare 11 and the rounded edge 26 in the transition from the groove 16 into a forward front face 27 of the connecting piece 2 still exists. However, the internal mantle surface 14 of the tulip flare 11 is only deformed so slightly that no force transmission occurs between it and the forward groove edge. The preferably remaining residual gap 25 prevents a pressure strain on the connecting piece 2 in its forward area and thus protects the cross-section 28, which is critical in regard to material damage. The sealing ring 17 is pressed sufficiently solidly into the groove 16 in the final mounted state that the gap 25 also has no negative effects on the tightness of the screw fitting provided.
FIGS. 4 and 4
a show a variation 1′ of the flared screw fitting, in which the union nut 4′ is provided on its internal mantle surface 18, in the forward section thereof, i.e., in the area 20′, in which it comes into contact with the external mantle surface 18 of the tulip flare 11 in the hand-tight pre-mounted state, with a bead 29, which projects inward in relation to the remaining mantle surface 18. There is a depression 30 between the bead 29 and the conical section of the remaining internal mantle surface 18 of the union screw 4′.
Only the final mounted position of the components to one another is shown in FIGS. 4 and 4a. In this position, the bead 29 is dug far enough into the external mantle surface 19 of the tulip flare 11 that the conical section of the internal mantle surface 18 of the union nut 4′ is also in contact with the external mantle surface 19 of the tulip flare 11. The very large-area support of the tulip flare thus provided results in a high strength of the pipe connection, in particular, movement of the pipe in the area of the tulip flare is prevented even in the event of greater external transverse force loads on the pipe 3. Furthermore, the dug-in bead 29 prevents the pipe 3 from being able to be torn out from the screw fitting in the event of greater longitudinal force effect with deformation of the tulip flare 11.
An increase of the security in relation to pulling out the pipe 3 may be achieved alternatively (or also cumulatively) to the bead 29 shown in FIGS. 4 and 4a with the aid of the embodiment shown in FIGS. 5 and 5a. The flared screw fitting 1″ shown therein comprises an alternative union screw 4″, which is provided in an area 32 with an internal mantle surface 18 having teeth 33. While in the hand-tight pre-mounted state of the screw fitting, the internal mantle surface 18 of the union screw 4″ is only in contact in the area of a forward bead 29′ with the external mantle surface 19 of the tulip flare 11, digging in occurs in this area upon advancing tightening of the screw fitting, so that an embankment 33 arises in front of the bead 29′—as also in the screw fitting shown in FIGS. 4 and 4a—which prevents the pipe 3 from being torn out. In the final mounted state as shown in FIGS. 5 and 5a, the tips of the teeth 32 are dug into the external mantle surface 18 of the tulip flare 11 and thus additionally prevent the pipe 3 from being pulled out.
A further alternative flared screw fitting 1′″ is shown in FIGS. 6 and 6a. In this variation, the connecting piece 2′″ has an external threaded section on both sides of the hexagon 6, specifically the external threaded section 5 (as does the connecting piece 2 as well) and the further external threaded section 34, which works together with a fitted internal threaded section 35 of a union nut 36. The union nut 36 has a through hole which is slightly larger than the external diameter of the pipe 3. A transmission ring 38 is located between a conical internal mantle surface 37 of the union nut 36 and the tulip flare 11, which is used as a transmission body for introducing force axially and radially into the connecting piece 2′″ together with the union nut 36. While the rear external mantle surface 39 of the transmission ring 38 has the same cone angle as the internal mantle surface 37 of the union nut 36 (namely 45°), the angular difference already explained on the basis of FIG. 2a exists in the hand-tight pre-mounted state between the internal mantle surface 40 of the transmission ring 38 and the external mantle surface 19 of the tulip flare 11. This angular difference, which is no longer visible in FIG. 6a, is equalized as the screw is tightened further up to the final mounted state in that in the forward area of the transmission ring 38, which is perpendicularly opposite in cross-section to the stop face 15 of the connecting piece 2′″, a deformation procedure occurs, which causes the material of the tulip flare 11 to flow slightly, so that after the mounting is completed, essentially the entire external mantle surface 19 of the tulip flare 11 is in contact with the internal mantle surface 40 of the transmission ring 38. There is also a gap 25 here between the rounded edge 26 in the transition of the groove 16 to the forward front face 27 of the connecting piece 2′″ and the internal mantle surface 14 of the tulip flare 11, which securely prevents shearing off of the most critical, smallest cross-section of the connecting piece 2′″ in the area of the groove base.
Of course, the transmission ring 38 may also be provided with a forward bead corresponding to that in FIGS. 4, 4a or teeth corresponding to the embodiment in FIGS. 5, 5a.
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List of reference signs
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1, 1′, 1″, 1′′′
flared screw fitting
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2, 2′′′
connecting piece
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3
pipe
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4, 4′, 4″
union screw
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5
external threaded section
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6
hexagon
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7
union nut (wire nut)
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8
internal threaded section
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9
external threaded section
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10
hexagon
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11
tulip flare
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12
through hole
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13
wire section
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14
external mantle surface
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15
stop face
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16
groove
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17
sealing ring
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18
internal mantle surface
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19
external mantle surface
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20
area
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21
diameter
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22
diameter
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23
gap
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24
length
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25
gap
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26
edge
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27
front face
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28
cross-section
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29
bead
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30
depression
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31
area
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32
teeth
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33
embankment
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34
external threaded section
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35
internal threaded section
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36
union nut
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37
internal mantle surface
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38
transmission ring
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39
external mantle surface
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40
internal mantle surface
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Patent Application
20070236016
