DE2349763A1 - FORCULAR SELF-LOCKING LOCKING ELEMENT - Google Patents

Description

The invention relates to an inevitably effective one Self-locking locking element with a screw that has a shaft and at one end an element to rest on includes on a workpiece surface. In particular, the invention relates to a form-fitting self-locking Screw that uses a compressible ring with a tapered segment near the end of the screw shank and the free outside of the workpiece in which the screw is located can interact to prevent that the screw without a special tool by means of which the ring can be compressed x ^ ground out of the Workpiece is pulled out.

The locking element according to the invention is is preferably a self-locking locking screw acting inevitably, in which at one end of the A fuse is provided for screw clamps,

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which inevitably secures the screw in a workpiece if the safety device is through a hole in the workpiece, into which the screw is inserted has passed. The fuse usually includes an annular groove on the Screw that widens outwards in the direction of the end of the screw, with the inclination of the widening the section runs in the direction in which the screw is inserted into the workpiece. A ring on his Outside diameter is elastically compressible, fits with Play and loose in the ring groove. When the ring is compressed in the radial direction or in its tensioned state is located, lying in the annular groove, its outer diameter not being greater than the diameter of the hole in the workpiece through which the screw is inserted. After the ring has passed through the hole in the workpiece, it expands it moves outwards into its relaxed state, with its outer diameter then being larger than the hole in the workpiece to which the screw is attached. The ring acts with a contact surface at the end of the screw and the outside of the workpiece in such a way that the screw is positively held in the workpiece. To expand the Screw a tool must be used to hold the ring where it can be compressed against the screw shaft when the screw is pulled out. It has been found that the screws described Kind of a critical relationship between the thickness of the compressible ring, its overall diameter, the length of the widening segment on the screw and the inclination of the widening segment must be adhered to to avoid a failure of the form-fitting self-locking "

The invention is based on the object of an inevitably effective self-locking lockable connecting element, in particular to create a screw with which it is ensured that

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that even then it cannot be pulled out of the workpiece can be applied when excessively strong forces attempting to loosen the lockable connector or if the connecting element is exposed to strong load changes or a load with vibrations.

This object is achieved according to the invention in that on formed the other end of the shaft an intermediate section with a device for form-locking self-locking is that the intermediate section is an outwardly widening one Includes segment whose diameter gradually increases from a smallest diameter to a largest diameter increases, which is smaller than the diameter of the shaft, that in addition to the intermediate section, an end section is formed which has a largest diameter, which is greater than the largest diameter of the expanding segment and not is larger than the diameter of the shaft, so that a bearing surface or shoulder next to the largest diameter of the widening segment that a radially inwardly compressible ring on the shaft around the intermediate section. is arranged around that the ring in the relaxed state has an outer diameter that is larger than the diameter of the shaft, and has an inner diameter which is smaller than the diameter of the end portion, so that the ring remains on the intermediate section so that the ring can be compressed radially inward to such an extent that its outer diameter is then at least equal to the diameter of the shaft that the diameter of the intermediate section on Shank plus twice the diameter of the cross-section of the ring is smaller than the diameter of the shank, so that the ring at the intermediate section are compressed radially inwards to an overall outer dimension can, which is smaller than the total outside diameter of the shaft, and that the angle of inclination of the expanding

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Segment is dimensioned so that when a portion of the ring touches the end portion, the distance from the longitudinal axis of the shaft to the center of the cross section of the ring is smaller than the radius of the end portion.

lockable In a preferred embodiment of the invention, the / Connecting element a form-fitting self-locking screw j in which the free end of the screw with an annular groove is provided, which merges into an outwardly widening segment, which extends on a radially outwardly Shoulder ends at the free end of the screw. A ring is arranged in the ring groove, the outside diameter of which is elastic is compressible. After the screw has been inserted into a workpiece, the ring acts on one side of the workpiece and the shoulder at the free end of the screw together in the sense that the screw is positively locked in the workpiece is secured so that the screw can only be removed from the workpiece when the compressible ring has been compressed radially inward. The contour of the expanding segment is set so that it is independent on the position of the compressible ring relative to the expanding segment the mean radius of the compressible ring is not greater than the radius of the Shoulder is. ■

An embodiment of the invention is in the drawings and is explained in more detail below. Show it:

Fig. I a Seitenansiäit, partially in section, of a formf positively self-locking screw in the installed state;

Fig. 2 is a schematic representation of the form-fitting

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Self-locking of a trained according to the invention Screw; and

3 shows an illustration similar to FIG. 2 of a self-locking screw which is inherently form-fitting and in which the self-locking fails after applying a releasing force in the presence of an alternating load.

In the figures and in particular in Fig. 1, a form-fitting self-locking screw 10 is shown in the installed state, by holding two workpieces 12 and 13 together. ' The screw 10 comprises a shaft 16 and a screw head 18 at one end, on which a support surface 20 is formed for a workpiece. The screw head 18 has any head formation; preferably it is around a hexagon 22. The screw shaft 16 can be of any desired clamping length, which is determined by the Thickness of the workpieces to be connected 12 and 14 is determined.

The end 24 of the screw 10 is provided with a threaded section, the largest diameter of which is preferably smaller than the diameter of the screw shank 16, so that the screw 10 during installation through the aligned through holes 28 inserted into workpieces 12 and 14 and so that a cylindrical removal tool over the end of the Screw can be pushed. An intermediate section 30 of the screw clip 16 comprises a segment with an annular groove 32, the diameter of which is significantly smaller than the diameter of the screw shaft 16. The segment with the ring groove expanded outwards to a conical segment 34 from the smallest diameter of the annular groove 32 to a «, largest Diameter at 36, the diameter at 36 being smaller than the diameter of the end 24, so that a shoulder 38 is formed will."

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An elastically compressible ring 40 extends around the intermediate section 30. The ring 40 is relaxed State a largest outside diameter, which is larger than the diameter of the through hole 28 in the workpiece, so that the ring with the outside of the workpiece 14 and the shoulder 38 on the shaft 16 of the screw 10 in the manner can cooperate to prevent the screw from being pulled out of the workpiece.

In a preferred embodiment of the invention form-fitting self-locking screw is after the screw 10 has been pushed through the workpieces 12 and 14 Nut 44 is screwed onto the threaded portion 26 and tightened to create a clamping force on the workpieces 12 and. 14 exercise. The nut 44 is provided with a counterbore 46, through which sufficient space for the ring 40, at which is a locking ring is created. The form-fitting self-locking of the invention Screw is a safety feature in the event that the nut 44 due to vibrations or by accidental Acceptance comes free or falls off. In certain applications, however, the threaded portion 26 and the Nut 44 can be omitted, so that only the ring is the form-fitting and establishes a self-locking connection.

Thus, the ring cooperates with the shoulder 38 and the outside 42 of the workpiece in the sense that it is pulled out the screw is prevented. In order to be able to remove the screw, a cylindrical removal tool (not shown) is used placed on the end of the screw in such a way that the ring 40 is pressed radially inward into the annular groove 32 and that is compressed. At the same time a Force applied by which the screw is sucked out or pushed out, so that the ping and screw

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pressed ring through the through hole 28 in the workpiece go through.

In the following, Fig. 2 is explained, in which an inventive formed end of a screw and the critical dimensions to be taken into account are shown. the Way in which the inventive form-fitting Self-locking screw acts can be better understood if the typical dimensions for a given Screw size are known. Accordingly, Fig. 2 shows typical ones Dimensions for a screw designed according to the invention.

Dimension A represents the hole diameter of the through hole in the workpiece through which the screw is inserted; Dimension B is the major diameter of the screw shank 16, which is approximately equal to the dimension A minus a tolerance that allows the screw to be easily inserted into the through hole; Dimension C is the diameter of the annular groove 32; Dimension D is the axial length of the ring groove. 32; Dimension Ξ is the diameter of the cross section through the compressible ring 40; Dimension F is the overall outer diameter of the compressible ring 40 in the relaxed state; Dimension G is the largest diameter of the conical segment 34 of the screw at 36? Dimension H is the largest diameter of the threaded section 26 of the screw biw. the outside diameter of the thread and leads to the formation of the shoulder 38 _c. The angle α reflects the inclination of the conical segment 34. It has been found that the angle α must be smaller than a critical maximum value in order to rule out failure of the form-fitting self-locking of the screw.

For a screw with a nominal diameter of 9/16 "(= 14.2875 inm)

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have the individual dimensions of a designed according to the invention Screw the values listed below.

A = 0.565 "= 14.3510mm

W = 0.562 "= 14.2748mm

C = * 0.432 "= 10.9728mm

D = 0.037 "= 0.9398mm

E = 0.060 "= 1.5240mm

F = 0.518 "= 14.7574mm

G = 0.472 "= 11.9888mm

H = 0.527 "= 13.3858mm

As can be seen from the table, there are certain relationships between the dimensions in order to obtain the desired screw To provide self-locking. The outside diameter of the relaxed ring 40, i.e. the dimension F, is 0.581 "(= 14.7574mm) and is therefore larger than the diameter of the through hole 28, i.e. the dimension A, see above that the ring 40 will not fit through the through hole in the workpiece unless it is compressed radially inward. Furthermore, certain other relationships between the dimensions must be observed. For example, the length is of the annular groove 32, i.e. the dimension D = 0.037 "(= 0.9398mm) and thus somewhat larger than the radius of the cross-section of the Ring 40, so that the ring when it is stretched and compressed, completely on the part of the ring groove sits with the smallest diameter. It can also be seen that the largest outside diameter of the ring 40 when it is compressed and rests on the annular groove 32, amounts to 0.552 "(= 14.0208mm) (dimension C + 2« E) and that this is 0.013 "(= 0.3302mm) less than the diameter the through hole, i.e. as the dimension A, so that the ring has sufficient tolerance to fit through the through hole.

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Since the ring has to be compressed radially inwards, to be able to remove the screw, and since the removal tool, which is used to press the ring against the screw shaft in the annular groove 32, preferably a cylindrical one Socket, the largest diameter of the threaded portion 26, i.e. the dimension H, should be smaller than the Diameter of the threaded shaft (dimension B) aain to enable that the removal tool is placed on the end of the screw and that the removal tool and screw go together fit into the through hole in the workpiece. Furthermore, the shoulder 38, the height of which should be equal to half the dimension H minus half the dimension G, have a minimum height so that a sufficient contact surface is formed so that the ring 40 cannot be printed over this contact surface. In the best case, this minimum amount is approximate equal to that and something more than the radius of the cross section of the ring 40. The contact surface for the screw described is 0.0275 "(= 0.6985mm) high ·, and thus slightly smaller than the 0.030" (= 0.7620mm) of the radius of the cross-section of the Ring 40.

To ensure that the form-fitting self-locking screw does not fail under tension, should certain minimum dimensions are observed. Therefore should the diameter of the cross section of the ring 40 must be made as large as possible to ensure that the Ring 40 does not fail under tension. However, since the ring 40 in the compressed state by the The through hole in the workpiece must fit, means an increase in the diameter of the cross section of the ring necessarily that the diameter of the annular groove 32 must be so small that it is twice the diameter of the Cross section of the ring 40 can be accommodated so that the ring fits through the through hole in the workpiece.

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Thus, there is an increase in the diameter of the cross-section of the ring, a reduction in the diameter of the annular groove 32 is necessary. However, this weakens the strength the screw excessively, since the screw breaks under high tension at the point of the smallest diameter knife would occur. Thus, the diameter of the cross section of the ring 40 and the smallest diameter in of the annular groove 32 can be selected so that a compromise between optimum strength of the ring and optimum strength the screw is hit.

In addition to the explained proportions of the dimensions and construction criteria, another * factor must be added to the Design of a screw according to the invention taken into account will. This is the inclination of the expanding segment 34, i.e. the angle α.

If the angle α of the conical section 34 is small and, for example, in the order of magnitude of 1, the Length of the expanding segment of the screw, i.e. dimension I in Fig. 2, is greater. If the dimension I is large and the nut 44 is unscrewed from the threaded section of the screw 10 (Fig. 1), there is a considerable margin, before the ring 40 comes into engagement with the outer side 42 of the workpiece 14. Furthermore, the support surface can then Remove 20 of the screw head from the workpiece 12 to an appreciable extent. In addition, the counterbore would have to be 46 of the nut 44, which is assigned to the screw, is made excessively long. Thus, the dimension should be In the best case scenario, I should be made as small as possible. The dimension I can be reduced by changing the angle α is increased to increase the inclination of the tapered segment.

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However, there is an upper limit up to which the angle α can be enlarged. Above this limit, a state is reached in which the self-locking of the inventive Bolt tends to fail when the bolt is subject to vibration and a force that affects the bolt tries to bring it out of engagement with the workpieces. This state is explained below with reference to FIG. When the nut 44 is removed and the screw is in a horizontal position or when the screw is in a vertical position and is subject to alternating loads or vibrations, the ring 40 tends to move in slide in the annular groove 32 so that the upper portion of the ring 40 lies in the annular groove 32, while the lower Section of the ring 40 outside the groove 32 is. If the screw is in this state and one through the Arrow R is subject to the force indicated by the screw trying to push it out, it moves into the workpiece into it, causing it to tilt the ring 40 so that the upper portion 48 of ring 40 into through hole 28 is moved into the workpieces, since this upper section rests against the annular groove 32 «, the lower section 50 of the ring 40 wedges between the outside 42 of the workpiece and the shoulder 38.

When the angle of inclination of the conical segment 34 exceeds a critical limit value, for example 20 ° and the ring is skewed, the distance from the longitudinal axis 52 of the screw to the center of the cross-section of the ring 40, - this distance is as dimension J in Fig. 3 shows -, larger than the radius of the outer diameter of the threaded section, i.e. larger than half the dimension H. If the shaft 16 in this state in the workpiece slides in, resulting in the lönstellation shown in dashed lines in FIG. 3, then the

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Force R, which tries to separate the screw from the workpiece, on the lower portion 50 of the ring 40. In this way acts a component of the reaction force of the force R on the lower portion of the ring. Since the distance from the Longitudinal axis 52 of the screw to the center of the cross-sectional area of the ring 40 is greater than the radius of the threaded section up to the contact surface, i.e. larger than half the dimension H, this component of the reaction force acts outwards, so that it tries to push the ring 40 outwards until it slips over the contact surface, which results in a failure of the self-locking.

From Fig. 2, in which the angle α! More than 20, preferably in the order of magnitude of 12 °, it can be seen that even with the ring at an angle .40 and Located in the annular groove 32, the upper portion of the ring is the distance from the longitudinal axis 52 of the screw to Center of the cross section of the lower portion of the ring 40 smaller than the radius of the outer diameter, i.e. smaller than half the dimension H. As long as this condition prevails, that is on the lower section of the Ring 40 acting component of the reaction force is directed inward, so that no failure of the ring due to a lateral evasion occurs. In this way it is avoided that the ring can tend to slip over the shoulder 38.

It has been found that the angle α is in the range should be between 1 ° and 20 ° and preferably in the order of magnitude of 12 °, around the length of the conical segment (Dimension I) to be as small as possible so that the screw clearance in the workpiece is as small as possible, if no nut on the threaded portion of the screw

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is screwed on. If the angle α is greater than 20 ° and the screw is arranged horizontally or is exposed to heavy loads with vibrations, the ring has 40 the tendency to lean on itself, so that a section of the ring goes into the through hole and it the leaves the remaining section to absorb the reaction force. However, as long as the angle α of the inclination of the segment 34 lies below the critical limit value, so that the distance from the longitudinal axis of the screw to the center point of the cross section of the ring 40 is smaller than the outer radius of the contact surface, the resulting Reaction force on the ring 40 directed inwards, whereby a lateral deflection of the ring section is excluded so that the self-locking is maintained.

The invention thus represents a form-fitting self-locking screw in which a failure of the self-locking itself It is then excluded if the screw is subject to an alternating claim or is exposed to vibrations.

Patent claims:

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Claims (6)

P a te n claims üche Form-fitting self-locking connection element with a screw that has a shaft as well as one of its End comprises an element for resting on a workpiece surface, characterized in that at the other end of the shaft (16) has an intermediate section (30) with a Device for form-locking self-locking is designed that the Zwxschenabschnxtt one after outwardly widening segment (34), the diameter of which gradually increases from a smallest diameter (C) increases to a largest diameter (G) which is smaller than the diameter (B) of the shaft (16), that In addition to the intermediate section, an end section (24) is formed which has a largest diameter (H), greater than the largest diameter of the expanding segment and not greater than the diameter of the Shank is so that a contact surface or. shoulder (38) In addition to the largest diameter of the expanding segment, there is also a radially inwardly compressible segment Ring (40) is arranged on the shaft around the Zwxschenabschnxtt around that the ring (40) in the relaxed state an outside diameter (F) which is larger than the diameter of the shaft (16), and has an inner diameter which is smaller than the diameter (H) of the end portion (24), so that the ring what remains at the intermediate section is that the ring can be compressed radially inwards to such an extent that its outer diameter then at least equal to the diameter of the shaft that the diameter (C) of the intermediate section on the shaft plus twice the diameter (E) of the cross-section of the ring smaller than the diameter 409816/0389 diameter of the shank, so that the ring at the intermediate section can be compressed radially inward to "an outer overall dimension that is smaller than the overall outer diameter of the shank, and that the angle of inclination (α) of the expanding Seg- ". Mentes is dimensioned so that when a portion of the ring touches the 'end portion (24), the distance from the longitudinal axis (52) of the shaft to the center of the cross section of the ring is smaller than the radius of the end portion. 2. Connecting element according to claim 1, characterized in that that the angle of inclination (α) of the expanding segment (34) is between 1 and 20. 3. Fastener after. Claim 2, characterized in that that the angle of inclination (α) of the expanding segment (34) is approximately 12. 4. Connecting element according to one of claims 1 to 3, characterized in that the intermediate section (30) has an annular groove (32) of immediately next to the shaft includes finite axial length (D), the diameter (C) of which is smaller than the diameter of the shaft, and that the annular groove merges into the outwardly widening segment (34). 5. Connecting element according to claim 4, characterized in that that the axial length (D) of the annular groove (32) is at least ι equal to half of the largest dimension of the cross section of the ring (40). 6. Connecting element according to one of claims 1 to 5, characterized in that the contact surface or shoulder 409816/0389 (38) of the largest diameter (G) of the expanding Segment (34) has a radial height that is approximately equal to the radius of the cross section of the ring (40) is. 409816/0389 Blank page