EP2349607A2

EP2349607A2 - Method for manufacturing a bolting part, tool for implementing the method, and device for tightening and loosening such a bolting part

Info

Publication number: EP2349607A2
Application number: EP09815468A
Authority: EP
Inventors: Carlos Rodrigues De Oliveira
Original assignee: RDO Alpha
Current assignee: RDO Alpha
Priority date: 2008-10-24
Filing date: 2009-10-23
Publication date: 2011-08-03
Also published as: US9028334B2; FR2937568A1; CN102196870A; MA32760B1; FR2937568B1; BRPI0919618A2; CA2738227A1; WO2010046611A3; AU2009306172A1; US20110183766A1; MX2011003368A; WO2010046611A2

Abstract

The invention relates to a method for manufacturing a bolting part, such as a screw (10) or a nut, comprising a head (12) comprising a perimeter (18) including at least one shoulder (20) extending in a radial plane. The method comprises at least the following shaping steps: shearing a wire of material (38) so as to obtain a part with a predetermined length, calibrating the part so as to correct the geometry of the part, blanking the calibrated part (34) so as to obtain the head of the bolting part, and finishing the blanked part by means of a third punch (36) so as to form a head comprising at least one shoulder (20), the calibration, blanking and finishing steps being performed only by cold stamping.

Description

Method of manufacturing a bolting part, tool for the implementation of the process, device for screwing and unscrewing such a piece of bolting

The present invention relates to a method of manufacturing a screw.

More particularly, it relates to a method of manufacturing a piece of bolting, such as a screw or a nut, comprising a head extending longitudinally between two ends, the head having in section in a plane perpendicular to the longitudinal direction a substantially circular shape, the head having a periphery comprising at least one shoulder extending in a radial plane.

It is known from the state of the art to make screws by cutting. However, this method causes a loss of material that is ejected during the formation of the screw in the tool.

It is known from GB 1913 113555 to make screws by hot forging. More particularly this document describes a screw head which is made to allow the screwing of the screw in a first direction, but to prevent the unscrewing thereof. For this purpose the screw comprises a head which has shoulders and which has a conical shape.

However the manufacture of screws by hot forging is long and expensive and no longer meets the current needs of industries using the screws of this type. The object of the present invention is to overcome these drawbacks and to propose a method of manufacturing tamperproof or removable screws with specific tools, the method offering increased production rates, without loss of raw material constituting the screw, while providing a manufacturing accuracy compatible with accepted tolerance thresholds. For this purpose, the manufacturing method as described above is characterized in that it comprises at least the following shaping steps: shearing a wire of material so as to obtain a piece of determined length, calibration of the workpiece in order to correct the geometry of the piece, that is to say to obtain end faces parallel to each other and perpendicular to the body, roughing of the calibrated part, so as to obtain the head of the bolts, finishing of the part sketched by means of a third punch so as to form at least one shoulder on the head of the bolting part, the calibration, roughing and finishing steps being carried out only by cold stamping.

With the cold-forming process, the material is deformed to obtain the final shape, without loss of material, and the production rates are improved over those of the prior art. According to other characteristics

prior to each shaping step, the piece of bolting is set up respectively in a first, a second and a third die and in that it is struck cold during each shaping step, at means respectively of a first, a second and a third punch.

The invention also relates to a tool for implementing the method described above, wherein: the first, the second and the third matrix are respectively arranged one after the other on a cold stamping line; the second punch has a fingerprint adapted to form a conical head; the second punch is adapted to form a head having a convex contour; the angle formed between the head and the longitudinal direction is between

0 and 45 °; the third punch is adapted to form n shoulders extending in radial planes, n being between 1 and 12, each shoulder forming with the subsequent shoulder an angle β such that β = 360 / n;

The present invention will be better understood on reading the following detailed description based on the appended drawings in which: FIG. 1 represents an overall view of the tooling line according to the invention, FIG. 2a shows a screw comprising three shoulders, FIGS. 2b and 2c show respectively a side view and a bottom view of the screw represented. in FIG. 2a, FIGS. 2d and 2e are views similar to those of FIGS. 2b and

2c, the shoulders being oriented in the opposite direction, FIGS. 3a, 3b and 3c respectively represent a perspective view, a side view and a top view of a screw whose head has a conical shape and comprises three shoulders. , Figures 4, 4b and 4c show views similar to Figures 3a,

3b and 3c of a screw whose head has a conical shape and comprises four shoulders, FIGS. 5, 5b and 5c represent views similar to FIGS. 3a, 3b and 3c of a screw whose head has a conical shape and comprises five shoulders, Figures 6a, 6b, 7a and 7b show a screw whose head has respectively a spherical shape and a curved shape, Figures 8a, 8b respectively show a sectional view and a bottom view of a screw device / Unscrewing associated with a piece of bolts according to the invention, illustrated in bottom view in Figure 8c, Figures 9a and 9b show a screw with a hollow head having a female cavity, Figure 10 is a bottom view of a punch and a punch insert according to the invention; Figures 10b and 10c show a sectional view and a bottom view of a punch according to the invention.

FIG. 11 illustrates a device for screwing and unscrewing according to a variant of the invention,

FIGS. 12 and 13 illustrate a device for screwing and unscrewing according to a variant of the invention

In the different figures, the identical references correspond to identical or similar elements.

Figures 2 to 5 illustrate screws 10 having a head 12 having specific means to prevent or make difficult the unscrewing thereof. Each screw 10 comprises a body 11 and a head 12, and extends longitudinally between a first end 14 of the side of the screw head 12 and a second end 16 opposite to the first. The screw heads 12 have in a plane perpendicular to the longitudinal direction X a substantially circular shape. Each screw head 12 has an outer periphery 18 on which at least one shoulder 20 is made.

Each shoulder 20 has a bearing face 22 and a convex portion 24. The bearing face 22 extends in a radial plane and is preferably arranged over the entire width I of the periphery 18.

As can be seen in FIG. 2a, 2b and 2c, the screw head 12 comprises three shoulders 20a, 20b, 20c oriented to the right, arranged in the forward direction, that is to say in the opposite direction of the needles of a shows. The bearing faces 22, on which a screwing / unscrewing device can come into abutment, allow easy screwing of the screw 10, in the clockwise direction, and unscrewing in the opposite direction of the needles. a watch. .

Figures 2d and 2e illustrate a screw head 12 for which the shoulders 20 are oriented to the left that is to say in the direction of clockwise.

As illustrated in FIGS. 3, 4 and 5, the screw heads 12 comprise respectively three, four and five shoulders 20. The number n of shoulders 20 made on the screw head is chosen according to the needs of the user. . However, on screws of standard size, the number n of shoulder 20 will not be greater than 12. Each shoulder forms with the consequent shoulder an angle β such that β = 360 / n. Figures 3, 4 and 5 the screw head 12 has a conical shape, the top of which is disposed on the side of the first end 14. The angle α formed between the longitudinal direction and the straight line passing through the inclined periphery is such that α is between 0 and 45 °. Unscrewing is possible for heads having an angle α between 0 and 7.30 °.

For αsuperior or equal to 8 °, the convex portion 24 of the shoulders 20 causes a difficult unscrewing, if not impossible with a standard tool, because the convex shape makes it virtually impossible to grip the head 12 of screws in a tool to loosen it.

In FIG. 3 α = 7.30 °°, in FIG. 4 α = 15 ° and in FIG. 5, α = 45 °.

The higher the value of the angle α, the greater the difficulty of unscrewing screws with standard tools. The combination of the shoulders 20 and the conical shape thus confers a double guarantee to prevent unscrewing of the screw. The value α will therefore be determined according to the needs of the user.

Figure 1 schematically shows a production line of a screw described above. The production line consists of three dies 26, 28, 30 cooperating respectively with three punches 32, 34, 36 respectively disposed in a punch insert 31a, 31b and 31c. The screw is obtained from a thread of material 38 which is struck cold between the dies 26, 28, 30 and the three punches 32,

34, 36correspondants, according to the following steps. The wire is first disposed in a first die 26 by means of a transfer clip 40. Then the first punch comes into contact with the first die 26 to calibrate the piece or piece of wire 38, that is, say to give it the full cylindrical shape. Then the calibrated obtained part is placed in a second matrix 28 by means of a transfer clamp. The second punch 34 comes into contact with the second die 28, by means of an automatic press 42a, for the step of roughing the screw.

With this step, the head 12 of the screw is formed without loss of material.

The head 12 of the screw may have a cylindrical shape or a conical shape as described above. The second punch 34 will be chosen according to the desired shape of the head 12.

In order to obtain the shoulders 20, the rough part obtained is placed in a third die 30 associated with a third punch

36 via the automatic press 42b. The third punch 36 is illustrated in FIG. 10. It comprises a cavity 44 representing the cavity making it possible to obtain the final screw head 12 with one or more shoulders 20.

Depending on the size of the bolt head, the number of dies and punches may vary.

Each of these three steps are performed by cold stamping, that is, by forging the materials at room temperature. This method is particularly advantageous because it allows high production rates, and there is almost no loss of material, and therefore little waste. In addition, unlike hot stamping, cold stamping does not require an additional step cutting the fibers, that is to say a clipping operation, when there is overflow of the material, to obtain the final product.

In addition, this method makes it possible to obtain greater precision during the manufacture of the parts and thus to reduce the manufacturing tolerances.

For this purpose the tools for implementing the method, and in particular the punches 32, 34, 36 and the matrices 26, 28, 30 are made by electroerosion, which offers a high accuracy of the dimensions of the screw obtained after striking.

In addition, the parts obtained have an improved resistance compared to those manufactured from the processes of the prior art, because the fibers of the material are not deformed.

According to other embodiments, the screw head 12 has a convex shape, as visible in Figures 6 and 7. The curved shape may be a part of a spherical or ellipsoid shape. In Figures 6a and 6b the head 12 having the shape of a ball formed by a sphere portion. This type of shape is of interest for hard-to-reach angles, for example when the alignment of the screw axis required for standard screwing and unscrewing is placed in a crowded and difficult to access environment. For example an automobile gearbox or any concentrated mechanical assembly preventing access or direct vision on the screw head. When manufacturing in cold stamping, the used punches are retractable to obtain spherical negative shapes.

In Figures 7a and 7b, the head has a convex shape. This variant is applicable to the assembly of elements that can be used by children, for example for toys. The rounded shape prevents chafing injury and prevents unwanted disassembly.

Figure 8 shows a screwing device 46 of a screw according to the invention having a partially spherical shape. The device 46 comprises a socket 48 comprising a female cavity comprising at least one shoulder 50 adapted to cooperate with at least one shoulder

20 of the screw head so as to drive the screw in the screwing direction and in the unscrewing direction. The female cavity of the sleeve 48 has the shape of a cavity having shoulders 50 arranged without the opposite direction to that of the screw head and adapted to drive the screw head in the screwing direction by cooperation of the surfaces of support and convex parts of the tool and head.

When the tool is brought in the unscrewing direction of the head, the convex portion of the tool bears tangentially on the convex portion 24 of the head. The convex portion 24 acts as a cam and the head is driven in the unscrewing direction.

FIG. 11 illustrates another type of device for screwing and unscrewing 52 a piece of fasteners according to the invention. More particularly, it illustrates a joint eye and flat key which has, at a first end 54, a symmetrical female cavity, according to an orthogonal symmetry with respect to a plane, of the shape of the head of the bolting part according to the invention.

At the second end, the key has a fork 56 having at least one shoulder oriented in the opposite direction to that of the head of the bolt. This type of device operates in the same manner as that described and illustrated in Figure 8 to screw and unscrew the bolts.

Other screwing and unscrewing devices can be used for screwing or unscrewing a head of a bolting part according to the invention. For example this may be wrenched wrenches, socket wrenches, open end wrenches, flat and tube wrenches, screwdriver bits, ratchet screwdriver bits.

Figures 12 and 13 illustrate an alternative embodiment of a tool or device for screwing and unscrewing a bolt part according to the invention. The tool makes it possible to apply a compressive force and a torque that makes it possible to drive the screw in rotation.

For this purpose, the tool comprises a substantially cylindrical longitudinal arm 58 and rotatably mounted in a tubular sleeve 60. The handle 60 and the arm 58 are arranged coaxially. The arm 58 has a first 62 and second 64 ends extending beyond the handle.

On the first end 62 is fitted a sleeve 64. The sleeve 64 is removably fitted on the end of the arm, and can be removed from the arm. The user can thus choose the bushing 64 adapted to the various forms of nut or screw according to the invention. For this purpose is provided a set of bushings having different impressions 66 and adapted to be fitted on the first end of the arm 58.

The tool further comprises a coaxial brass ring 68 and disposed on the side of the first end 62 of the arm. The ring 68 acts as a stop for the sleeve 64, when the latter is biased in translation in a direction of unscrewing.

An elastic means 70, forming a compression spring, is disposed adjacent to the stop 68, and absorbs the translational movement of the sleeve 64, transmitted via the ring 68, during unscrewing. The tool works as follows. When the user wishes to screw a nut or a screw according to the invention, he chooses the bushing 64 adapted to the screw or nut determined, and engages the bushing 64 on the first end 62 of the arm 58 of the tool. The user applies manually or using a press, visible in Figure 13, a force to move the tool in axial translation in a first direction to the screw or nut. When the screw or the nut is engaged in the socket, the user exerts on the arm a force torque tending to rotate the arm 58 in a first direction of rotation corresponding to the screwing, while maintaining the axial force. The couple is transmitted to the sleeve 64 via the integral connection between the first end 62 of the arm and the sleeve 64.

When the user wishes to unscrew the screw or the nut, he always exerts an axial force so as to maintain the nut or the screw engaged in the sleeve 64. Then he exerts on the arm a torque of effort tending to unscrew the screw or nut. The screw or the nut then tends to move in translation in a second direction, reverses the first direction and exerts an axial pressure on the tool. This pressure is transmitted to the elastic means 70 via the sleeve and the ring 68 forming a stop. Thus the pressure exerted on the screw does not prevent unscrewing and consequently its movement in translation in the second direction.

FIG. 9 illustrates another embodiment of a piece of bolting made from the method according to the invention. In this embodiment, the head comprises a hollow female cavity having three shoulders. This embodiment has the same characteristics and the same advantages as those described above. The associated tool then has a socket having shoulders oriented outwardly and adapted to cooperate with the female footprint of the head of the bolt. The invention is in no way limited to the described and illustrated embodiments which are given by way of example only. In particular the invention can be applied to a piece of bolts such as a nut.

Claims

claims

A method of manufacturing a bolting part, such as a screw (10) or a nut, having a head (12) extending longitudinally between two ends, the head (12) having in section in a perpendicular plane in the longitudinal direction (X) a substantially circular shape, the head (12) having a periphery (18) comprising at least one shoulder (20) extending in a radial plane, characterized in that the method comprises at least the steps following formatting:

Shearing a material thread (38) so as to obtain a piece of determined length,

Calibrating the part so as to correct the geometry of the part, that is to say to obtain end faces (12) and (16) parallel to each other and perpendicular to the body (11),

Roughing of the calibrated part (34), so as to obtain the head of the bolting part,

Finishing the blank with a third punch (36) so as to form a head having at least one shoulder

(20)

The calibration, roughing and finishing steps are performed only by cold stamping.

2. The manufacturing method according to claim 1, wherein, prior to each shaping step, the bolt piece (10) is placed respectively in a first, a second and a third die (26, 28, 30). ) and in that it is cold-stamped, at each forming step, by means of a first, a second and a third punch (32, 34, 36) respectively.

3. Tool for the implementation of method according to claim 3, characterized in that the first, second and third dies (26, 28, 30) are respectively arranged one after the other on a striking line. Cold.

4. Tool according to claim 3 wherein the second punch (34) has a recess adapted to form a conical head (12).

5. Tool according to claim 3, wherein the second punch (34) is adapted to form a head (12) having a circumference (18) curved shape.

6. Tool according to claim 6, wherein the angle (oc) formed between the head (12) and the longitudinal direction (X) is between 0 and 45 °.

7. Tool according to claim 3 wherein the third punch (36) is adapted to form n shoulders extending in radial planes, n being between 1 and 12, each shoulder forming with the consequent shoulder an angle β such that β = 360 / n.

8. Device for screwing and unscrewing a bolting part obtained from the method according to claim 1, characterized in that it comprises a female cavity having at least one shoulder (50), oriented in the opposite direction to that the bolt part, and adapted to cooperate with at least one shoulder (20) of the head (12) of the bolt piece so as to drive the screw in the screwing or unscrewing direction.

9. Device for screwing and unscrewing a bolting part obtained from the method according to claim 1, characterized in that it comprises a longitudinal handle (60), in which is mounted freely rotatable an arm (68). , a bushing (64) being mounted at the end of the arm and having an imprint (66) corresponding to a bolt part obtained according to the method of claim 1.