Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
  • F16B31/00—Screwed connections specially modified in view of tensile load; Break-bolts
  • F16B31/02—Screwed connections specially modified in view of tensile load; Break-bolts for indicating the attainment of a particular tensile load or limiting tensile load
  • F16B31/028—Screwed connections specially modified in view of tensile load; Break-bolts for indicating the attainment of a particular tensile load or limiting tensile load with a load-indicating washer or washer assembly

Definitions

• the invention relates to a device for controlling screw connections according to the preamble of patent claim 1.
• the invention further relates to a method for producing such a device according to claim 13.
• Screws are known in a wide variety of applications. They are used for detachable connection of at least two parts. For reliable attachment of the parts sufficient axial force of the screw is required. The torque acting on the screw when screwing in causes the axial force or preload force via the thread.
• DE 31 48 730 C2 discloses an interposer disk unit in which a measuring body is provided between two disks which are formed by balls of different diameters which are embedded in an elastic layer.
• the DE offers
• a device for controlling force-locking connections in which a measuring system is provided with two disc-shaped components, which comprises a measuring layer of, for example, piezoelectric material.
• a disk which has an angled section which is continuously pressed against the component as it is tightened by the nut or screw.
• US 6,152,665. the disc is provided with cuts, which limit bulging strips which are pressed by the mother or the screw when tightening continuously to the component. In this case, the strips are dimensioned such that they protrude in the pressed state over the outer diameter of the disc.
• the invention aims to remedy this situation.
• the invention is the task
• a device for controlling screw connections is created, which reliably and with the naked eye indicates the achievement of a defined biasing force, is simple and works purely mechanically.
• the metastable state of the display element achieved by means of mechanical pretensioning causes it to experience a significant, erratic, perceptible deformation with the application of a defined pretensioning force acting on the device.
• This type of training has the advantage that a deformation of the display element takes place only when the predetermined torque is reached. In this way it is prevented that at a merely approximately sufficient bias voltage, which, however, does not correspond to the design-side specified torque, no change of the display element occurs. It is thus ensured that the device according to the invention only upon reaching the prescribed torque of the screw, or the defined bias, gives feedback.
• the triggering of the transition from the metastable state to the steady state is associated with an acoustic noise, whereby an additional perception of the achievement of the defined tightening torque is given.
• Essential to the invention is the provision of a preload in the washer, whereby a "force reservoir" is formed which, upon reaching the required preload force, permits an abrupt deformation of the washer or a region of the washer (transition from the metastable to a stable state) the known in the prior art continuous deformation of a portion which is difficult to perceive by the naked eye and which can characterize the achievement of a certain torque or a certain biasing force insufficient here, there is a sudden, significant change of a first state into a second an immediate perception of the achievement of a defined biasing force that triggers the transition from the metastable into the stable condition is required.
• the washer is made of a spring steel.
• the device is integrally formed.
• the device according to the invention comes out with only one additional component, namely the washer.
• the washer In the event that a washer is provided for the screw anyway, the number of components is even unchanged.
• the display element is formed by a radial portion of the washers.
• the radial section at least partially on a reduced material thickness.
• an outer radial portion is biased against an inner radial portion which is funnel-shaped extending axially outwardly extending.
• a lever mechanism is effected, which allows a change of a metastable state into a stable state by the defined biasing force, even with larger material thicknesses.
• the outer edge of the inner radial portion is formed embossed such that it has a nearly flat, horizontal surface.
• a flat, inner annular surface is arranged, to which an axially conically from the plane of the inner annular surface extending out collar adjoins, which is integrally formed on the inner ring portion, so through the inner ring portion and the collar an annular circumferential curvature is formed, which preferably has a cross section in the form of an upside-down V.
• At least one arcuate, preferably annular groove is introduced on one side of the washer, which extends between two radial sections.
• the washer has a thickness of ⁇ 0.8 mm, preferably ⁇ 0.7 mm. It has been shown that this ensures a reliable triggering of the transition from the metastable to the stable state. In this case, good results were achieved in the manufacture of washers made of a spring steel.
• the invention is further based on the object to provide a method for producing a device for controlling screw connections, which reliably indicates the achievement of a defined biasing force, is simple and works purely mechanically. According to the invention, this object is solved by the features of claim 13. (The design of the disc before application of the axial force corresponds to the stable state, as it can be seen from FIG. 4 or FIG. 9).
• the washer assumes a metastable state, as shown in FIG. 5 or FIG is shown.
• a washer is set in a metastable state, so that it performs a sudden, significant deformation in response to a defined bias by a defined tightening torque of the screw or the nut of the screw in a defined area, which with the naked eye is clearly visible.
• the second funnel-shaped section has at least twice, preferably at least four times, particularly preferably at least five times, the width of the first funnel-shaped section. This causes a clearly visible, erratic deformation during the transition from the metastable state to the stable state.
• Figure 1 is a schematic representation of a screw with a
• Figure 2 is a schematic representation of the screw according to Figure 2 before tightening the nut (not strained state);
• Figure 3 is a schematic representation of the washer of the screw of Figure 2 in plan view;
• Figure 4 is a schematic representation of a screw with a
• Control device in a further embodiment (not strained state);
• Figure 5 is a schematic representation of a washer for a
• Figure 6 shows the schematic representation of the washer of Figure 5 in the stable, braced state
• a screw connection comprising a threaded bolt 1, which protrudes from an indicated component 2.
• a nut 3 On the thread of the threaded bolt 1 is a nut 3 auf- screwed. Visible between the component 2 and the nut 3 serving as a control washer 5 is arranged.
• the washer 5 is substantially circular in shape, with an inner ring section 51 having a passage 52 and an outer ring section 53.
• the display element is formed by the outer ring section.
• the washer 5 is biased, whereby it is brought into a met astabilen state.
• the outer ring portion 53 forms a flat annular surface, from which the inner ring portion 51 protrudes hollow frustoconical.
• the nut is located on this hollow truncated cone-shaped inner ring portion 51 (see Figure 2).
• the inner ring section 51 is embossed on its edge facing the nut 3, so that the edge 54 in this frustoconical state of the inner ring section 51 forms a planar contact surface formed parallel to the nut 3.
• the inner ring portion 51 Upon further screwing the nut, the inner ring portion 51 is pressed in the direction of component 2 until it rests flat on the component 2. For this purpose, the complete overcoming of the bias of the washer 4 is required. By overcoming the pretensioning, the washer is "released", whereby it is suddenly transferred into the stable state, whereby the outer ring section 53 assumes a conically widening in the direction of the nut 3, this collar-like enclosing state (see FIG. This stable state is also maintained in a later loosening of the nut, so that in this embodiment, the outer ring 53 forms a reliable display element recognizable with the naked eye, whether the mother originally with the required defined torque or with the defined preload force has been tightened.
• control device is formed by a washer 6 in a further embodiment.
• a mirrored to this on the inner ring portion of the washer 6 is formed, whereby an inner, arranged on the level of the outer ring portion 63, a bushing 62 having inner
• Ring surface 64 is formed, which is connected via a conically widening collar 65 with the edge of the inner ring portion 61.
• the inner annular surface 64 is dimensioned smaller than the circumference of the nut 3, so that when tightening the nut 3, a part of the biasing force acts on the collar 65, over which ultimately the 6 required to trigger the washer force is introduced to the inner ring portion 61.
• This design allows the realization of a device according to the invention even for very large required tightening torques, since only a part of the biasing force is initiated as a triggering force in the inner ring portion 61.
• a washer 7 which has an inner ring section 71 having a bushing 72 to which an outer ring section 73 adjoins, is likewise used in the screw connection as a control device. Also in this embodiment, the display element is formed by the outer ring portion.
• the washer 7 is also biased, whereby it is spent in a metastable state.
• the inner ring portion 71 is formed frustoconical from the inside to the outside widening upward and merges into the outer ring portion 73, which forms an outwardly rising annular surface ( Figure 5).
• a wave-shaped intermediate portion 74 Arranged between the inner ring portion 71 and the outer ring portion 73 is a wave-shaped intermediate portion 74 which has a cross-section in the form of a "lying S.”
• This intermediate portion 74 initially runs counter to the slope of the inner ring portion 71 and then enters the slope via an inflection point of the outer ring section 73.
• the nut (not shown in FIG.
• the outer ring section 73 forms a reliable display element, as it does only after reaching the stable State rests on the component. As a result, it can be recognized with the naked eye whether the nut has originally been tightened with the required, defined torque or with the defined preload force.
• An optical support of the display element formed thereby can be achieved in that the outer edge of the outer ring portion 73 is at least partially provided with a paint reservoir, which is destroyed by the sudden turning of the outer ring portion 73, whereby the color emerges circumferentially of the outer ring portion.
• the exemplary embodiment according to FIGS. 5 and 6 also has the advantage that after a sudden reaching of the stable state, a bias voltage for additional securing of the screw connection is formed. Further, in the washer 7 according to this embodiment, the support surface changes from the inside to the outside, whereby penetration of the washer 7 is prevented in the component surface. This washer 7 is therefore particularly suitable for soft component materials.

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• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Bolts, Nuts, And Washers (AREA)

Applications Claiming Priority (2)

Publications (1)

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ID=54252148

Family Applications (1)

Country Status (5)

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Citations (7)

• 2015
  • 2015-10-01 NO NO15187980A patent/NO3150868T3/no unknown
  • 2015-10-01 PL PL15187980T patent/PL3150868T3/pl unknown
  • 2015-10-01 EP EP15187980.6A patent/EP3150868B1/de active Active
  • 2015-10-01 DK DK15187980.6T patent/DK3150868T3/en active
• 2016
  • 2016-07-06 WO PCT/EP2016/065924 patent/WO2017054946A1/de not_active Ceased

Patent Citations (7)

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