EP1572394B1 - Screw plug made of a metallic material, method for the production thereof, corresponding blank, and corresponding tool - Google Patents

Abstract

Disclosed is a screw plug (10) for a liquid conduit, particularly an oil pipe or an oil container, comprising a cylindrical shaft (36) that is placed on a top plate (12) and is provided with an external thread (22). A pocket hole (28) having a polygonal cross section is centrally arranged on the top plate as a receiving member for a tool. The shaft (36) is embodied as a tubular butt (14) that is provided with the external thread (22). A pocket hole (18) which is arranged coaxial to the pocket hole (28) of the top plate (12) extends from the face (16) of the shaft. In order to produce said screw plug (10), a blank comprising the cylindrical tubular butt (36) that is connected to the top plate (12) in a molded-on manner is made, the inner diameter and outer diameter of said tubular butt (36) being smaller than the final corresponding diameters (e, f) of the screw plug (10). The tubular butt (36) of the blank is then enlarged by applying pressure to the inner wall surface of the pocket hole thereof. Also disclosed is a tool for carrying out the inventive method, in which one end of a pressure die is fixed as a mandrel-type tool while a supporting or holding head which is disposed so as to be movable relative thereto and encompasses a seat for a blank is associated with the free end thereof.

Description

The invention relates to a method for producing a screw plug made of metallic material for a fluid line - in particular for an oil line or an oil vessel - with a cylindrical shaft containing an external thread on a ridge plate, in which centrally provided a blind hole polygonal cross-section as a receiving member for a tool is.

From the EP-A-0 461 344 is a provided with blind hole plastic plug known.

The GB-A-1 274 754 shows a metallic screw plug.

From the JP 57 151246 U a closure screw is known which has a blind hole on a side opposite a drive opening. The production of such a screw is relatively expensive.

Screw plugs of this type are mainly used in motor vehicles and must therefore be produced in large quantities. It has proven to be favorable so far that their production must be carried out in at least three stages of production. To improve this improvement is the object of the invention.

To achieve this object, the teaching of the independent claim; the dependent claims indicate favorable developments. In addition, all combinations of at least two of the features disclosed in the description, the drawings and / or the claims fall within the scope of the invention.

In a screw which can be produced by the method according to the invention, the shaft is designed as a tube stump provided with the external thread, and a blind hole coaxial with the usual blind hole of the ridge plate emerges from the end face of the shaft of the locking screw. Of particular importance is that at one of the ridge plate achswärts - at a longitudinal angle of preferably 30 ° - inclined and widening firstward phase section as a transition to the pipe stump the rohrwärtige foot contour of this phase section at the same time - constructive - inner approach line for over this contour radially protruding external thread should be. Otherwise, a diameter of the foot contour of the phase section of 19.5 mm is preferred.

As low it has proven to have the deepest hole of the blind hole of the pipe stump have a inclined from the wall surface to the screw longitudinal axis cross-section; Advantageously, the depth of the wall surface should be about 8 mm, in particular 7.8 mm.

According to a further feature of the closure screw which can be produced by the method according to the invention, the diameter of the blind hole measures approximately 14 mm and the external diameter of the external thread measures approximately 21 mm; the dimensions should in particular cover the values of 13.8 mm or 20.97 mm.

The shaping of the closure screw which can be produced by the method according to the invention also comprises at least one, and preferably one on both sides, a phase edge inclined away from this tube edge toward the ridge plate, the outer phase edge merging into the external thread should.

In the context of the invention is a method for producing this screw plug, in which a blank is produced with an integrally formed on a ridge plate subsequent cylindrical stump, the inner diameter and outer diameter are formed shorter than the intended, this corresponding diameter of the screw plug; the tube stump of the blank is widened by simultaneously creating pressure on the inner wall surface of its blind hole. According to another feature of the invention, a plunger is driven as a mandrel tool in the blind hole of Röhlingrohrstumpfes and radially widened by this wall of the pipe stump.

It has proved to be beneficial if the outer surface of the pipe stump on the foot contour of the at Ridge plate subsequent - cross-sectionally inclined to the axis - phase portion of the blank pushed out radially becomes; the external thread is to be formed in the tube outer surface of the flared tube stub, advantageously in the achswärts of that foot contour of the phase section specific region of the tube stub. This molding is advantageously carried out after the production of the above-described shape of the screw plug by a separate thread rolling process.

However, within the scope of the invention is also a method in the course of which the outer surface of the pipe stump is pressed during its expansion against a surrounding mold surface with threaded negative.

Of particular importance is the blank used for the process for producing the closure screw; in this connects to the ridge plate a cylindrical pipe stub of an outer diameter and a diameter of the blind hole, the dimensions of which are shorter than the outer diameter and the hole diameter of the actual screw plug; The diameter of the blind hole should measure about 12 mm and the outer diameter of the pipe stump about 19 mm, preferably 19.2 mm. The dimensional difference to the final product is compensated by the expansion process.

Also, it has proved to be favorable to choose the outer diameter of the pipe stub on the blank shorter than the foot diameter of the phase section on the screw plug; the latter - as well as the phase section of the blank - should enclose an angle with the blank longitudinal axis, which preferably measures about 30 °.

According to another feature, the pipe edge of the pipe stump on both sides is assigned in each case one of the pipe edge inclined away phase edge, wherein the outer phase edge merges into the cylindrical pipe outer surface.

Of importance is also a tool with which the deformation of the blank can be done in a simple manner; According to the invention, a plunger is set as a mandrel tool at one end in a housing and the free end of a relatively movably arranged support or holding head associated with a receptacle for a blank; the axis of which runs in the central axis of the tool or the plunger. It is also beneficial that at the that the support or holding head far end of the sleeve-like housing, a stationary base plate is provided which forms an abutment for her seated plunger. According to the invention, the free end of the plunger partially surrounded by a plunger tube is intended to engage in a central bore of the support or holding head, a printhead of the plunger then projecting axially beyond the mouth edge of the plunger tube. For this purpose, it has proven to be advantageous if this stamp tube at the other end - preferably with a disc base - a stationary stationary sleeve of the tool is seated, which forms a support surface for the stationary sleeve passing through plunger. In order to improve the printing process, a central pressure base can be formed on that base plate, which forms a common abutment for the plunger and the stand sleeve.

It is preferred that the carrying or holding head of the tool is seated on a sliding sleeve, which is associated coaxially with the pressure ram and the stationary sleeve. The diameter of the pressure base should then correspond approximately to the seated diameter of the sliding sleeve.

The latter has, moreover, on a base portion assigned to the pressure base, a head portion which is radially widened relative to the latter and is intended to be held in a retaining manner by the holding head by a guide chuck and to be arranged so that it can move axially relative to the housing.

To support the movement of the base plate and the guide chuck, a force store is arranged according to the invention between these tool parts, in particular a profile element of elastic material. This profile element is preferably placed annularly around the pressure base of the base plate and can be made of strands of material of different cross-sectional shape.

Finally, it has proved to be favorable that the blank sitting in the supporting or holding head blank can be pressed in its axial movement on the print head of the plunger, wherein the diameter of the plunger is greater than the diameter of the blind hole in the blank, i. when inserting the plunger, the blank expands.

Overall, a captivatingly simple method for producing the closure screws mentioned above results.

Fig. 1:

eine skizzenhafte Schrägsicht auf einen erfindungsgemäßen Rohling für eine Ver- schlussschraube;

Fig. 2:

einen Diametralschnitt durch die Ver- schlussschraube;

Fig. 3:

eine der Fig. 2 entsprechende Darstellung des Rohlings zur Herstellung der Ver- schlussschraube;

Fig. 4:

den Längsschnitt durch ein Werkzeug zum Herstellen der Verschlussschraube mit oberhalb eines Pressstempels eingesetztem Rohling vor Beginn des Formvorganges;

Fig. 5:

die der Fig. 4 entsprechende Darstellung des Werkzeuges am Ende des Formvorganges mit entstandener Verschlussschraube;

Fig. 6:

den Längsschnitt durch den Presstempel mit zugeordnetem Rohling.

Further advantages, features and details of the invention will become apparent from the following description of a preferred embodiment and from the drawing; this shows in

Fig. 1:

a sketchy oblique view of a blank according to the invention for a closure screw;

Fig. 2:

a diametrical section through the cap screw;

3:

one of the Fig. 2 corresponding representation of the blank for the production of the closure screw;

4:

the longitudinal section through a tool for producing the screw plug with blank inserted above a press ram before the beginning of the molding process;

Fig. 5:

the the Fig. 4 Corresponding representation of the tool at the end of the molding process with a developed screw plug;

Fig. 6:

the longitudinal section through the ram with associated blank.

A screw plug 10 for a not shown for reasons of clarity oil line or oil tank of a motor vehicle has on a plate-like ridge plate 12 axial height b of 4.5 mm and the diameter d of about 27 mm to the longitudinal axis A of the screw plug 10 axially integrally formed pipe stump 14th the outer diameter f of 20.97 mm; the axial height a of the screw plug 10 measures 19 mm, from which a height c of the tube stump 14 of 14.5 mm is calculated.

In the stump 14 a - from his designed as a pipe edge 16 face - blind hole 18 of diameter e of 13.8 mm and the wall depth c of 7.8 mm provided, the lowest 20 of the wall surface 19 of the blind hole 18 for Screw longitudinal axis A out - viewed in cross-section - is centrally inclined, so forms a flat conical surface. Those tube edge 16 accompanies the blind hole 18 towards an inclined phase edge 15th

Such an inclined phase edge 17 also surrounds the tube edge 16 from the outside and merges into an external thread 22 of that external diameter f of 20.97 mm and the height h of 12 mm. At the upper edge of the external thread 22 includes a molded, to the ridge plate 12 in a cross-sectional angle w of 30 ° (s. Fig. 3 ) conically expanding phase portion 24 axial height i of 2.5 mm. Its randwärtiger foot diameter g measures 19.5 mm. The external thread 22 attaches to the rohrwärtige foot contour 25 of the phase portion 24 and protrudes radially beyond this.

From the surface 13 of the ridge plate 12 is a central blind hole 28 hexagonal cross-section of the diameter z of about 4.8 mm (SW 10) and the wall depth y of 7 mm. Its hole deepest 30 is also centrally inclined from the wall surface 29 to the screw longitudinal axis A, also forming a flat conical surface. In this first blind hole 28 is used to rotate the screw plug 10 a - not reproduced in the drawing - tool.

For producing the screw plug 10 is a in Fig. 3 illustrated blank 34 made of metal (for example, from 19 MnB ₄ ) made of - the ridge blind hole 28 containing - ridge plate 12 and an integrally formed thereon cylindrical tube stub 36; while the ridge plate 12 in its and its blind hole 30 dimension (b, d, y, z) corresponds to that of the finished screw 10, the tube stub 36 of the blank 34 is different to the tube stub 14 designed. The pipe outer surface 38 is here at the end of the ridge plate 12 far end - also the final dimensions g, w having - inclined phase portion 24 at; the diameter f _{1 of} its cylindrical contour is 19.2 mm, that is to 1.77 mm shorter than the outer diameter f of the finished screw plug 10. The diameter e ₁ of the existing in the blank 34, to the inner phase edge 15 _{a of} the pipe edge 16 _a subsequent blind hole 18 _a measures 12 mm, that is 1.8 mm shorter than the diameter e of the finished screw plug 10. The outer phase edge is denoted here by 17 _a .

For the production of the screw plug 10 from the blank 34 whose tube stub 36 is widened approximately by driving a mandrel into the blind hole 18 _a and pressure generation on the latter wall surface 19 _a precisely to the tube stump 14, which easily the male thread 22 is able to be formed.

A tool 40 for a preferred way of producing the screw plug 10 is the 4 to 6 refer to. Coaxial with its central axis M is a cylindrical tool housing 42 of the exemplary outer diameter q of 120 mm, a base plate 44 with centrally formed pressure base 46 of a diameter q ₁ of 60 mm and a height n ₁ of 21.5 mm and associated with a radial stepped bore 45.

On the pressure base 46 sits a stand sleeve 48 of length n ₂ of about 47 mm with an axial bore 47, which offers a cross-sectionally expanded end portion 47 _{t of} the diameter t ₁ of 16 mm. This axial bore 47, 47 _t receives a plunger 50 as a mandrel tool, the above the standing sleeve 48 a plunger tube 54 of length n of almost 60 mm from a pipe section 55 with this integrally formed Tellerfuß 57 of diameter t ₃ of about 40 mm surrounds; the outer pipe diameter t ₂ measures 21 mm, the inner diameter t of the pipe interior 58 about 14 mm. The latter continues downwards through those axial bores 47 of the stationary sleeve 48. In addition to the axial bore 47, 47 _t and to her at a radial distance extending in the stationary sleeve 48 is still an axially parallel bore 49 of narrower diameter, which is aligned with a corresponding bore 49 _a in the base plate 44.

On the stationary sleeve 46 of the diameter q ₂ , a sliding sleeve 60 of a height of about twice the length n ₂ mentioned above is attached to the outside; the lower edge 62 sits in Fig. 5 the centric pressure base 46 of the base plate 44. The cylindrical outer surface of the lower half and the foot portion 64 _{t of} the sliding sleeve 60 continues the outer surface of the pressure base 46 and defines a cylindrical cavity 63. In a length n _{2 of} the stationary sleeve 48 approximately corresponding distance to that lower edge 62 starts a wider head portion 64th the sliding sleeve 60, which carries on its ridge end 66 a holding head 68 - upwardly tapered cross-section - with a central bore 70; this takes up the upper end of the tube section 55 of the plunger tube 54, whose outer diameter t _{2 determines} the diameter of the bore 70. The height n _{3 of} the holding head 68 is slightly shorter than the length n _{2 of} the stationary sleeve 48.

Between the outer tool housing 42 on the one hand and the sliding sleeve 60 and the holding head 68 on the other hand extends a space filling, also sleeve-like guide chuck 80. This encloses the sliding sleeve 60 and the holding head 64 conclusive and can be moved together with these inner parts together as a unit in the tool housing 42 become. In the area of that cavity 63, it is provided with a thread 81 for a threaded sleeve 84 which extends in that cavity 63.

43 with a directed towards the center axis M towards the guide edge of the housing 42 is designated 41, with a radial guide member which engages in an axially parallel guide recess 82 of the guide chuck 80.

The ridge portion of the bore 70 is adapted in cross-section to the structural design of the screw plug 10, ie the diameter of the bore 70 corresponds with a small clearance - the outer diameter f of the tube stump 14 of the screw plug 10 and expands approximately in the axial height b of the ridge plate 12 corresponding distance from the end face 76 of the holding head 68 of a conical ring plane 72 of the bore wall 71 - corresponding to the inclined phase portions 24 of the screw plug 10 - up to a step 74, according to which Fig. 4 the ridge plate 12 of the blank 34 is placed. The circumference of the pipe stub 36 extends in a ring distance to the bore wall 71 of the central bore 70th

During this insertion process is the phase edge 15 _{a of} the blank 34 - at a distance from the mouth edge 56 of the tube section 55 - on the corresponding inwardly inclined ridge or phase edge 51 of the endwärtigen section or print head 52 of the plunger 50, which the mouth edge 56 of the punch tube 54th surmounted accordingly. The diameter of this Firstrandes 51 corresponds to the diameter e of the blind hole 18 of the screw plug 10, that is greater than the corresponding diameter e ₁ on the blank 34th

For the printing or molding process, the guide chuck 80 is lowered within the housing 42 in the direction x to the base plate 44 against a indicated at 78 profile ring approximately circular cross section of elastic material, ie the distance s between them is reduced, the punch or printhead 52 of the stationary plunger 50 into the blind hole 18 _{a of} the blank 34 penetrates and the tube stub 36 expands until the outer surface 38 of the bore wall 71 of the bore 70 is present. The dimension k of here 7 mm of the pressure path is in Fig. 5 recognizable. Those arranged between the base plate 44 and guide plate 80 profile ring 78 may be otherwise configured cross-section otherwise than in Fig. 5 outlined; optionally it is designed as a hollow profile.

After the molding process, the not quite finished screw plug 10 _{r is} removed from the holding head 68 and its expanded pipe stub 36 equipped with the external thread 22; then the screw plug 10 is ready for use.

Claims (11)

1. Method for producing a screw plug for a liquid line, in particular for an oil line or an oil vessel, comprising a cylindrical shaft (36), having an external thread (22), on a ridge plate (12) in which a blind hole (28) of polygonal cross-section is provided centrally as a receiving member for a tool, the shaft (36) being formed as a pipe butt (14) provided with an external thread (22), and a blind hole (18) which is coaxial with the blind hole (28) of the ridge plate (12) proceeding from the end face (16) of the shaft, the screw plug consisting of metal material and comprising a phase portion (24), which is inclined from the ridge plate (12) towards the axis, as a transition to the shaft (36), characterised in that a blank (34) is produced with a cylindrical pipe butt (36) which is integrally attached to a ridge plate (12), the internal diameter (e1) and external diameter (f1) of which pipe butt are formed so as to be shorter than the provided corresponding diameters (e, f) of the screw plug (10), and in that the pipe butt (36) of the blank is expanded, generating pressure on the internal wall surface (19a) of the blind hole (18a) thereof, and in that when the pipe butt (36) is expanded the external surface thereof is pressed against a shaped surface surrounding it and having a negative of the thread, or in that the external thread (22) is integrally formed by a separate thread rolling process.
2. Method according to claim 1, characterised in that a portion (52) of a pressure piston (50), which portion has a cross-section exceeding the internal diameter (e1) of the pipe butt (36) of the blank (34), is inserted into the blind hole (18a) of said pipe butt as a mandrel tool which radially expands the pipe butt, and/or in that the external surface (38) of the pipe butt (36) is pressed radially outwards by the base outline (25) of a phase portion (24) which is attached to the ridge plate (12) and is inclined towards the axis in cross-section.
3. Method according to either claim 1 or claim 2, characterised in that an external thread (22) is integrally formed in the external pipe surface (38) of the expanded pipe butt (36).
4. Method according to claim 3, characterised in that the external thread (22) is integrally formed in the region of the pipe butt (36) axially defined by the base outline (25) of the phase portion (24), and/or in that the external thread (22) is integrally formed in the external surface (38) of the pipe butt (36) by the thread rolling method.
5. Method according to claim 4, characterised in that the external surface (38) of the pipe butt (36) is pressed against a shaping tool enclosing said pipe butt.
6. Method according to any one of the preceding claims, characterised in that the screw plug is formed in such a way that the base outline (25), towards the pipe, of the phase portion (24) is an internal positioning line for the external thread (22) which projects radially past this outline.
7. Method according to any one of the preceding claims, characterised in that the screw plug is formed in such a way that in longitudinal section the phase portion (24), extending towards the ridge, of the screw plug (10) forms an angle (w), preferably measuring approximately 30°, with the longitudinal axis (A) of the screw plug.
8. Method according to any one of the preceding claims, characterised in that the screw plug is produced with a diameter (g) of the base outline (25) of the phase portion (24) of 19.5 mm.
9. Method according to any one of the preceding claims, characterised in that the screw plug is formed in such a way that the bottom (20) of the blind hole (18) of the pipe butt (14) has a cross-section inclined from the wall surface (19) thereof towards the longitudinal axis (A) of the screw plug, a depth (c) of the wall surface (19) of approximately 8 mm, in particular of 7.8 mm, optionally being provided.
10. Method according to any one of the preceding claims, characterised in that the screw plug is produced with a diameter (e) of the blind hole (18) of approximately 14 mm and an external diameter (f) of the external thread (22) of approximately 21 mm, in particular of 13.8 mm and 20.97 mm respectively.
11. Method according to any one of the preceding claims, characterised in that the screw plug is formed in such a way that at least one phase edge (15 or 17) inclined away from the pipe edge (16) towards the ridge is associated with said pipe edge, one phase edge (15, 17) inclined away from the pipe edge (16) towards the ridge optionally being associated with said pipe edge on either side and preferably transitioning into the external thread (22).

Images