DE2039906A1 - Device for renewing a thread seat - Google Patents

Description

Patent attorneys Dr. Ing.Walter Abitz Dr. Di-3 ^ r F. Morf Dr. HpV. - \ Prauns August 11 , 1970

8Milnchen36, Plenzemuerstr. 28 849 095

BESBRUCH-HOFMANN, INC. Lindenhurst, N. Y., V. St. A.

Device for renewing a thread seat

The present invention relates to a device for renewal a threaded seat in a holder and in particular a tool for broaching a threaded hole and. renewed cutting of a thread, as well as further one threaded liner sleeve for the newly threaded threaded hole.

So far, there have been considerable difficulties with thread seating for spark plugs in engine blocks made of relatively soft metals such as aluminum. The threads in the thread seat of the engine block often loosen when the spark plugs are removed, like this difficulty in reinserting the spark plugs in the engine block.

The present invention relates to a tool which can be used to enlarge a hole © has a loosened thread turn by opening the hole

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is expanded to a larger diameter and a new thread is cut in the enlarged hole. It is Therefore, the object of the present invention to provide a single tool with which a spark plug receiving Hole in relatively soft metal is expanded in order to enlarge the hole while a coarse thread groove is formed and a new thread is cut in the enlarged bore.

The present invention provides a tool fen, which has a substantially cylindrical body

P formed on one side thereof with a head supported by a key for rotation of the tool can be detected about its axis, the tool having a number of circumferentially spaced apart has radial ribs extending longitudinally of the body, and each of the ribs consists of three sections, namely a first section. at the other end of the body, which when turning of the tool enters the bore and the broaching process begins, the second section being adjacent to the first section Section is shaped in such a way that it completes the reaming of the bore and runs a rough helical

tk fende groove therein, while the third section adjacent to the second section is formed with thread cutting channels which cut a new thread turn in the broached bore, and the thread cutting channels are guided through the coarse helical groove while the tool is used to form an enlarged, is rotated again tapped hole.

The invention is then illustrated by means of exemplary embodiments described in connection with the drawings. Show it

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Figure 1 is a side view of a spark plug which is in a lining sleeve | in an extended, with a new threaded hole located in an engine block, with liner sleeve and the portion of the Engine blocks are shown in a vertical section,

Figure 2 is a side perspective view of the liner sleeve;

Figure 3 is a perspective view of the tool used to enlarge the bore in the engine block and. is used to cut the thread again,

FIG. 4 shows an enlarged vertical section along the line 4-4 in FIG.

Figures 5 and 6 show enlarged cross-sections longitudinally lines 5-5 and 6-6 of Figure 4 and

FIG. 7 shows a view of the tool from below same scale as figure 3

In Figs. 1 and 2, a lining sleeve 10 is shown, which is provided with a thread inside and outside and which is in a threaded hole 12 of the engine block is recorded. The hole or hole in question has the same diameter D as the one with thread before it is enlarged and before the thread is applied provided base 14- of the spark plug 16. The cylindrical liner sleeve 10 has at its upper end a .Ringflansch 18, against which the nut flange 20 of the Spark plug attaches. The liner sleeve is provided with an internal thread 21, which consists of V-shaped threads

or grooves, which in the corresponding thread turns and grooves of the spark plug base 14 engage · The off

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Sengewinde 26 has V-shaped threads 28 and a groove 30 which runs flat at the base of the thread. the The width of the groove 30 in the axial direction of the liner sleeve essentially corresponds to the maximum axial width the thread turn 28 at the bottom of the same. The bore 12 is provided with a thread 35, which on the external thread the liner sleeve is matched. A helical groove 32 is V-shaped in cross section and the helical flight 34 is provided with a flat top.

The liner sleeve 10 is inserted into the bore 12 by first screwing the sleeve onto the spark plug base 14 is, whereupon the assembly of spark plug with sleeve is screwed into the bore 12, the flat Groove 30 is locked with the flat ridge 34 and a subsequent removal of the spark plug does not detach the lining sleeve 10 from the engine block 11.

Tool 50 is in formation in Figures 3-7 the threaded hole 12 is shown. The tool is formed with a number of axially extending ribs 52, which extend circumferentially at a distance in the radial direction of the tool. Each rib has three in the longitudinal direction at a distance from one another sections 53, 54 and 55, which increasingly greater lengths L, L ', and L ". At the upper or outer end of the tool, a hexagonal head 56 is arranged, the can be captured by a suitable key. The head is provided with a cylindrical extension 58. Grooves 60 extend in the longitudinal direction of the tool from the extension 58 down to the tool end 62. The grooves 60 are A concave cylindrical design, as can be seen from FIGS. 5 and 6. In the end section 53 is a cutting rib provided, which by sharp, hollow ground channels

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th 66 and smooth outer sides 68 is limited. The ribs 64- are, starting from the end 62, inclined slightly outwards and in the longitudinal direction upwards towards the section 54. "The middle section 54 of each rib (FIG. 6) is provided with ribs 69 and grooves 71, the respective flat upper sides The longitudinal edges 69 'are ground hollow and the circumferential or transverse edges 70 are sharp. The edges 66s in the various central sections 54 are aligned in a screw line leading around the tool. The upper or inner section 55 each rib provides a thread cutting gear with hollow ground, axial edges 73 are. V-shaped ribs 72 in the portions 55 are aligned helically around the tool, to form a ^ continuous screw flight. the ribs 72 are separated in the axial direction of the tool by grooves 74 from each other, which run flat in their bottom part.

When using the tool 50, the narrowest end 62 is first in a. Bore H with thread T inserted, which is to be enlarged. The bore can consist of a damaged threaded seat for a spark plug in the engine block 11. The tool is turned by means of a wrench and the cutting ribs 64 initially cause the bore to be broached. Subsequently, the sections 54 continue the broaching of the bore while they form a coarse, helically extending rib and groove, the shape of which essentially corresponds to the grooves 71 and ribs 69. The coarse groove formed by the sections 54 serves to guide the tool and pulls it axially inward into the bore H, which is widened and provided with a thread. This is an important feature of the invention which makes it easier to rotate the tool to complete the threading. Finally, those with

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winch provided sections 55 into the cleared, roughly grooved Bore and form the fully expanded and precisely threaded bore 12.

After the bore 12 in the engine block 11 has been completed, the arrangement consisting of the liner sleeve 10 and the spark plug 16 is inserted into the bore 12 in the above manner. The lining sleeve is preferably made of a lead-steel alloy, so that after the arrangement in the bore 12 has been tightened firmly, the wet threads 26 flow and create a gas-tight connection with the thread 35 of the bore 12.

The tool 50 is preferably made from tool steel. It can be used repeatedly and has a long lifespan. The invention enables a quick and easy reinsertion of spark plugs in damaged or inaccurately cut thread seats in engine blocks. While the primary purpose of tool 50 is to enlarge and re-thread threaded seats for spark plugs, it will be apparent that the tool can have general use in tree and tapped holes and re-threading.

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Obviously, other modifications of the invention are possible and these will be described in the following Claims encompassed by the invention.

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Claims (1)

84-9 095 H II August 1970. Pat ent a n β τ> back Device for renewing 'a damaged thread' in a ffotorbiöek or the like, characterized by a Tool which has an essentially cylindrical body, at one end of which a head is provided is »which can be detected by a key, W to rotate the tool around its axis, with a number of circumferentially spaced, radially directed hips that extend lengthways of the body, each of the ribs having three sections and a first portion at the other end of the body is shaped to fit into the threaded bore enters and initiates the mumming process, if the tool is rotated, with the second next to the first portion arranged portion formed in such a way is that it completes the treeing of the threaded hole and a rough, helical nat cuts, while the third section, lying next to the second section, is formed with thread and cutting passages is. which in. the broached bore sin new thread cutting, whereby the thread cutting passes are guided through the coarse, helical groove, while the tool is being rotated to in the said block to create an enlarged opening with a new thread - · 2 «Device for renewing a thread seat Claim 1, dadszrch characterized in that 3'ede of the ribs is hollow ground and the first section of each rib consists of a cutting rib, which with sharp Edges are formed that extend outwards and in the longitudinal direction of the body from said other load starting out to tree the damaged threaded hole to undertake. -7- 109810/1531 3 · Device for renewing a thread seat according to Claim 2, characterized in that said second portion of each rib is alternating flat Has ridges and shallow grooves and the ridges and grooves in the second section of the various ribs are arranged helically in alignment with one another around the body. 4. Device for renewing a threaded seat according to Claim 3 »characterized in that the threads in said third section of each rib are V-shaped Have ridges that alternate with other flat grooves, the V-shaped ridges and flat ones other grooves in the third sections of the various ribs in helical alignment around one another the body are arranged. 5 »Device for renewing a thread seat according to Claim 1, characterized by a cylindrical Sleeve that.in the enlarged, with a new thread provided seat can be used, and the one intended for receiving a threaded element internal thread has and an external thread, which is matched to 'the thread of the newly cut seat is, wherein the sleeve has a radial annular flange at one end, which is supported on the engine block, when the sleeve is fully seated in the recut seat. 6. Device for renewing a threaded seat according to claim 5 »characterized in that the thread of the recut thread seat a helical, V-shaped comb. has, which has a helical, flat base, and that the external thread of the cylindrical - 8 109810/1531 095. ¹ ^ drical sleeve another helical, Has a V-shaped comb which has a further helical, flat base surface owns which on the base and the comb of the newly cut thread seat is matched. 7 · Device for renewing a thread seat according to Claim 5 »characterized in that each of the said ribs is ground hollow, and the first section of each rib consists of a cutting rib, which has sharp edges starting from one end of the body outwards and in the longitudinal direction of the body are inclined to initiate broaching of the defective thread fit, and the second section each rib has alternating flat ridges and grooves, the flat ridges and grooves of the second Section of the various ribs are helically aligned with one another around the body. 8. Device for renewing a thread seat according to Claim 7> characterized in that the thread cutting paths V-shaped in the third section of each rib Have ridges that alternate with further shallow grooves, the V-shaped ridges and other flat ones Grooves in the third section of the various ribs, helically shaped with one another, in alignment around the body are arranged. 9 · Device for renewing a thread seat according to Claim 8, characterized in that the thread of the renewed threaded seat has a helical, V-shaped ridge which has a helically extending flat base, the male thread of the cylindrical sleeve another helical, V-shaped m. Q - 109810/1531 095 JtO has a shaped crest with a further helical flat base, which is matched to the base and the crest of the new thread seat 1098 10 / ^ 5.3