DE2165105C3 - Process for the production of ball head bolts - Google Patents

Description

maintain great hardness, even after the

45 by means of high frequency induction heating or

-heating carried out heat treatment of the

The invention relates to a method for producing spherical parts. This has a noticeable resistance a ball head bolt, which is responsible for steering or increasing deformation in the case of the kom-suspension device a motor vehicle used cold forming process result and is bar; in particular it concerns a heat treatment- 50 shortens the life of the deformation process, where a low carbon steel testifies. If in addition to the original material or a low-alloy steel as the starting material, a decarburization layer, d. H. a layer with For the production of a hollow ball-headed boar, less C, is present, results from the high eduction which is not the desired when stressed by induction hardening Divide-like and variously large shock loads - 55 surface hardness in the starting material, because these genes, vibrations and various other decarburization layers less or no C defaced Strains a long service life. As a result, the wear is resistant. The method of heat treatment and the stand of the spherical part of the ball head bolt in usually for the manufacture of the ball head bolt is generally considerably reduced. It is to be used Materials are required as follows, the entire surface layer divided or differentiated: the ball head bolt or the ball surface to

remove to remedy the above mentioned problem.

1. First method According to the second method, the ball

65 head bolts with the exception of the spherical surface before the anti-carburization treatment

A low-alloy steel with more than 0.40 ™ / oC layer can be given, for example a copper as a starting material for the ball head pin coating or some other appropriate means, and

lat-h of the case hardening these surface layers, which had been subjected to the anti-carburization treatment, completely removed will. These operations increase the manufacturing cost of the ball head bolt. In addition, must be special Care should be taken to ensure that the ball head bolt due to the penetrating into it Hydrogen gas produced by the acid pickling required to remove the anti-carburization layers comes from, does not become brittle.

In third known methods, cold working, case hardening, etc. can be quite easy be performed; however, if the threaded portion of the ball head stud passes through different load conditions, for example complicated shock loads from several directions, Is subjected to vibrations, etc., a high fatigue resistance is given.

The invention relates to a method for producing a ball head bolt in which the output material a low carbon steel or alloy with excellent cold deformation properties is used; aside from that

ίο is compared with this starting material lighter carburization heat treatment applied to the known carburization heat treatment, resulting in a ball head bolt that

Ball head bolts same

over the well-known "

the high-frequency heating is remunerated, the 15 or even better characteristic properties Has the tip or the head of the screw bolt faster.

heated than the rest of the bolt, so that the process characterized by the claims

not evenly tempered entire bolts. Remedial measure for the production of a spherical head- To remedy this disadvantage, the Zwi- bolt is easier and simpler to drive than the known vertion coil and the screw bolt in general, and it can be compared to the known about the normal state enlarged, why
the high-frequency induction coil having such an unusually large spacing requires a multiple of electrical energy than that coil
necessary, which has a normal coil spacing.

In addition, the shank part of the ball head bolt is hardened and whitened by the case hardening
has such a high surface hardness that the formability or ductility or toughness is noticeably reduced.

As things stand, the ball head bo! / En should advantageously have the following properties:

35

1. Since the spherical surface of the ball head bolt continuously irregular rotation and Gleitbzw. Is subject to sliding movements, selected procedures with a shorter procedure time Manufacture ball head bolts with the same or better properties.

According to the invention, a low-carbon bolt is used as the starting material for the production of a hollow ball head bolt or a low carbon alloy steel is used which has a carbon content of 0.12 to 0.23% (e.g. JIS S-15C, S-20C, SCM-21-23) and can be processed excellently at room temperature; this starting material is then molded and heat-treated according to the following process steps.

The starting material is shaped as a ball head bolt and the hole surface of this ball head wood given a specific case hardening treatment; then the heat treatment is carried out in the usual way carried out and finally

When it is under a vibrating load, only the spherical part of the ball head bolt should * o Surface hardness have a hardness number by means of high frequency induction heat treatment is higher than 60 on the Rockwell Scale, hardens or case-hardened.

and a sufficient wear resistance. This shows the metallic structure of the upper. In addition, the spherical head surface layer should be made of martensite and the metallic bolt through a diffusion treatment of the 45 structure of the ball interior made of sorbitol, troostite and Surface carbon of the ball end pin is formed by ferrite, while the surface layer of the

Shank part and the threaded bolt part made of sorbitol and their inner part made of sorbitol, troostite and one smaller amount of ferrite is formed.

The abbreviations used for the steels mentioned in detail are at the end of the description explained.

The invention is explained in more detail below with reference to the drawing. This shows in

F i g. 1 is a temperature time graph of the heat treatment process for a ball head bolt according to the invention,

2 shows a temperature-time diagram according to the first known method,

3 shows a temperature-time diagram according to the second known method,

F i g. 4 shows a temperature time diagram according to the third known method;

5a schematically shows a hollow ball head bolt The invention is therefore based on the object 65 and a test device for

F i g. 5 b, plotted in a diagram of test results by means of the test device according to FIG Fig. 5a performed loading tests,

be made sufficiently malleable.

2. In any case, it should be avoided that the bolt and its interior become uneven are hard, which is the case with decarburization or carburization. Furthermore the bolt part should have sufficient elastic extensibility, sufficient have high yield strength and tensile strength. On the other hand, the shaft part of the ball head bolt should also excellent tensile strength and yield resistance to have. In particular, the shank part of the ball head bolt should have a high resistance to Bending stress and a high level of fatigue or Alternating strength can be granted.

to eliminate the above-mentioned disadvantages of the known ball head bolt and to develop a method through the ball head bolt, although he

5 6

Fig. 17 exerted on the central part of the ball shows the fine structure of the inner part of the shaft

Bending stress over the center point of the ball and the screw bolt of the ball head bolt performed bending deflection is applied, the application of the well-known third heat

FIG. 5c shows a diagram according to FIG. 5b, in which the treatment method, ferrite + Troostil + one, however the ordinate of the absorption energy is due to the amount of martensite, four hundred times the magnification, tion-

F i g. 6 the hardness distribution in the hardened As the starting material for the production of the

Layer of the spherical part of the ball head bolt, the ball head bolt according to the invention is an insert

7 shows the work of deformation or the deformation steel, for example JIS · SCM-21, with a content of deformation resistance, plotted against deformation of 0.13 to 0.18 ° / oC, 015 to 0.35 'VuSi, 0.60 to mation ratio, where K, or o> the deformation 0.85%> Mn, 0.9 to 1.2 ° / oCr, less than 0.3O <VoCr, resistance or the deformation work of the ball less than 0.30 ° / oNi and 0.15 to 0.30 ° / oMo, head bolt material (JIS · SCM-21) according to the application. This starting material will mean heat treatment, while on the other hand it means crimping, in order to produce spherical carbide and, in the same way as K ₁ ' or w, the deformation resistance or the state of a cross-sectional round rod or the deformation work of the spherical head bolt material of a wound or coiled round rod ( JIS · SMC-4) according to the state of the art. The coiled round rod is first placed at room temperature in a raw material

F i g. 8 a photographic image of the hollow ball head bolt designated as the Feinling reshaped, structure of the spherical surface layer of the spherical head 20 where that in Japanese patent specification 15 548 / bolt according to the heat treatment according to the invention - 1969 described manufacturing process for application process, martensitic, polluted a hundredfold. Then the hollow ball head bolt enlargement, in a carburizing oven equipped with a carburizing

F i g. 9 the fine structure of the inner ball part of the rierungsatmosphärengas with a dew point of Ball head bolt is filled to a suitable temperature after the heat treatment 25 + 10 ° C drive, sorbitol + troostite + ferrite, heated four hundred times between 890 and 920 ° C, the corresponding Enlargement, chosen the carbon content of the ball head bolt

Fig. 10 shows the fine structure of the spherical surface. In the case of a layer of the ball head bolt designated in Fig. 1 with the point A according to the known Neten temperature of 800 ° C, propane gas is used as enrichment gas magnified 100 times as enrichment gas in the first heat treatment process, martensitic, in order to increase the carbon content of the surface F i g. 11 to enlarge the fine structure of the spherical inner part, layer of the blank, with the atmosphere of the bolt shank part and the surface layer spherical gas being kept at a dew point temperature within the range of the inner part of the bolt shank part and between + 5 and 3 ° C. The surface layer as well as the inner part of the screw period in which the blank is held in the temperature range of the bolt of the ball head bolt according to the known between 890 and 920 ° C, depends on the first heat treatment process according to Fig. 10, according to the desired depth of carburization of the raw sorbitol, four hundred times magnification, for example 1 hour for a depth of about FIG. 12, the fine structure of the spherical surfaces - 0.5 mm. The supply of the enrichment gas is interrupted in the layer of the ball head bolt after the application 40 time D, which is at the beginning of the last third of the known second and third heat treatment storage time, whereupon the treatment process, martensite + residual austenite, one hundred blank in the period C to D, as shown in FIG. 1 Earth-fold enlargement, visible, at the above-mentioned temperature of the Dif-Fig. 13 the photographically recorded joint fusion carburization treatment is subjected to the same fine structure of the ball inner part of the ball head bolt 45 After the end of the diffusion treatment process after the application of the known second (D), the blank is suddenly quenched in the oil bath of, for example, or third heat treatment process and the 50 ° C. The inner fine surface layer and the inner part of the shaft structure of the blank consists according to the above-mentioned or the screw bolt of the ball head bolt after heat treatments from a larger amount of the application of the known second heat - 50 martensite and a small amount of troostite and ferrite, treatment process, ferrite + troostite + one small This fine structure completely satisfies the required amount of martensite, four hundred times magnification, which struggled with the quenched structure of the er-Fig. 14 the same fine structure of the surface layer of the shaft steel JIS · SCM-21, which was recorded in accordance with the invention and used as the starting material. Since, in addition, the screw bolt part of the ball head bolt is to be hardened from the spherical part later by the high frequency according to the invention as well as the surface layer of the induction heat treatment screw bolt after the application of the known, the surface carbon content of the spherical third heat treatment process, sorbitol, four-part of the Ball head bolt easily by influencing a hundredfold magnification, the atmospheric gas dew point in the carburizing figure. 15 the fine structure of the inner part of the shaft 60 process can be regulated. Therefore, if the surface and the screw bolt part of the spherical head bolt carbon content of the spherical part is chosen to be about 0.60 ° / after the application of the heat according to the invention, the surface layer of the spherical treatment process, sorbitol + troostite + a smooth part through the high-frequency induction heat rings Amount of ferrite, four hundred times magnification, treatment quenched satisfactorily, and e Fig. 16 the fine structure of the shank part of the ball 65 shows in the surface layer of the spherical head bolt after the application of the heat treatment part a completely quenched martensitic treatment process according to the invention, ferrite + Troostite structure. That is, the inner fine structure of the ball + martensite, four hundred times magnification, and the head bolt, which is created by the application of heat

2 1 (55 105

(ο

treatment method of the invention was obtained, is in marked contrast to that of the ball head pin in accordance with the known heat treatment methods in which selected by the application of a Karburierungsgasatmosphäre having a dew point of about IOC a ObcrflächenkohlenstofTgehalt in a range of 0.7 to 0.9 ⁿ / o is, the diffusion heat treatment to improve the machinability of the shaft part is carried out at a temperature of about 800 C, which is lower than the usually used carburizing temperature of about 900 C, and at which is then quenched and the internal fine structure obtained from a smaller amount of martensite and a larger amount of troostite and ferrite.

According to the heat treatment method according to the invention, the blank is immediately after Carburizing and quenching process tempered in a temperature range between 420 and 430 C. The resulting fine structure is made of sorbitol, which is in the carburized surface layer is present, composed, while the fine structure of the inner part of sorbitol and a minor Amount of troostite and ferrite is composed. For this reason, the ball head bolt according to FIG Invention has excellent mechanical properties and improved toughness.

After the blank has been completely remunerated. the entire surface of the spherical part will continue subjected to a high frequency induction reduction or hardening. In this quenching or hardening treatment the heating depth is in the range from about 0.6 to 0.8 mm. If necessary. a tempering treatment at a relatively lower temperature range, for example between 150 and 200 C.

The ball head bolt produced by the described method according to the invention is in his Performance and its properties noticeably improved; besides, the manufacturing cost is compared to those of the ball head bolt produced by the known method is significantly lower.

F i g. 1 to 4 show temperature-time diagrams from which the results of the method according to the invention can be seen in comparison with those of the known methods; 1 shows details of the method according to the invention as a function of time, FIG. 2 the well-known first process. F i g. 3 the known second process and FIG. 4 the well-known third process. In the figures, the Y-axis means the heat treatment temperature and the Y-axis means the heat treatment time. It still means

C ₁ : start of carburization (addition of the enrichment gas),

C.,: Maximum heating temperature, C _{: 1} : tempering temperature.

C, ': diffusion temperature and quenching or Curing temperature,

C ₄ : tempering temperature at a relatively lower level.

OE on the Y-axis: quenching or hardening time,

EH: payment period,
5

HJ: high frequency induction quenching time,

JM: compensation period at a relatively lower level,

Ca: carburization time,
d: DiiTusionsbchandlungszeit.

With particular reference to Figures 3 and 4, CC " denotes the cooling time, OO ' the anti-carburization time, HM the time required to remove the anti-carburization protection, and JY the air cooling time.

As can be seen from FIGS. 1 to 4, the heat treatment time OM for producing the ball head bolt according to the invention is compared with the treatment time in the known methods according to FIG. 2 to 4, the shortest. The Vergülungstemperatur C ₁ lies in the method according to the invention, as shown in F i g. 1 can be seen, around 420 C, whereas the tempering temperature C in the known first method is between 550 and 600 C, which is why the tempering time EH can be shortened in the method according to the invention. In addition, the compensation time EH both the known second and third in the known method according to F i g. 3 and 4 each longer than in the method according to the invention, since the tempering treatment is carried out at a relatively lower temperature after the quenching.

The mechanical properties and other characteristics of the according to the method of the invention manufactured ball head bolts are compiled in Table 1, for comparison, the properties of the known ball head bolts are given, which have almost the same size as the Kugelkopfbolzcn according to the invention, by means of the known Methods have been manufactured and are currently used in Japan and the United States for automobiles and the like will. In this experiment, a Kugclkopfbolzcn in the form of FIG. 5 a used Its dimensions are folacnde:

D = 26 mm 7>,

d - ■ 14.46 mm Φ,

/ 22.4 mm,

L. 54 mm.

The ball center point of the ball head bolt

is in the direction of arrow P according to FIG. 5 a loaded. to

Carrying out load tests 6, 7 and 8 ii Table 1 is the ball head bolt 1 in the Versucl

by means of a screw nut 2 on a Einspannvor

direction 3 attached. P indicates the direction of the bend

load, the fall load and the bicgungsmü

application load. The Vct

Search results are based on attempts "made via drc

Years followed and in the years 1967 to 196 '

were carried out. The structures and state variables mentioned in Table 1 are based on the Heat treatment conditions of the ball head bolt and the fine structures shown in FIGS. 8 to 17.

The results of the load tests are from FIG. 5 b and 5 c can be seen. F i g. 5 b shows the Central part of the ball exerted bending stress over the deflection, while Fig. 5c shows the Shows absorption energy over the deflection deflection at the central part of the sphere. According to these results has the due to the inventive heat treatment process manufactured spherical head bolts in comparison to the spherical head bolts manufactured on the basis of the previously known heat treatment process excellent shock resistance, strength and ductility. Above all The ball head bolt according to the invention shows things, as can be seen from FIG. 5b, during the bending test no break.

F i g. 6 shows the hardness distribution of the ball of the finished ball head bolt, the change in hardness of the ball surface being plotted against the distance from the surface of the spherical part. Curve A shows the hardness distribution of the spherical part that has been quenched or hardened by the high-frequency induction heating process according to the invention, while curves B, C and D each correspond to the hardness distributions of the spherical head bolts produced according to the known first, second and third processes. From these hardness distribution curves it is clear that, due to the additional high-frequency induction hardening according to the invention, a superior hardness distribution results in the surface layer of the spherical part, although the carburization concentration and its depth are lower. For comparison, curve A ' shows the hardness distribution of the ball head bolt according to the invention before high-frequency induction heating.

In Fig. 6, the ordinate gives the hardness value according to the Rockwell C scale and the abscissa the respective depth of the surface layer in mm. The decrease between the hardened surface layer and the inner part is slight, from which the noteworthy Advantages of carburizing and high frequency heating treatment according to the invention become clear.

There is used as starting material is a low carbon steel or a low carbon alloy steel having a content of 0.12 to 0.23 ⁰ OC and is excellent workable at room temperature, in the method according to the invention, as described above, the life of the punch can made of high speed steel and used for hollowing out the hollow ball head bolt can be remarkably elongated.

From Fig. 7 shows the deformation ratio versus the deformation resistance or the deformation work performed, where K ₁ , K ₁ ' correspond to the deformation resistance (kg mm ² ) of the steels JIS · SCM-21 or JIS · SCM-4, while c>. «·>'Correspond to the deformation work performed (mm kc mm ¹ ) of steels JIS · SCM-21 or JIS - SCM-4. Accordingly, the values kg mm * and mm-kg mm * apply to the ordinate, while the abscissa indicates ^{the deformation ratio of the steels used in 0 O.} From Fig. 7 is easily seen.

that both the deformation resistance ah as well as the deformation work performed in the case of the carbon steel JIS SCM-21 15 to 20 "used in accordance with the invention. ¹ O are lower than the steel JIS ■ SCM-4, S is for example used in the known first manufacturing method. This is of decisive advantage of prolonging the life of the tools used. Thus, with respect to, for example, a punch tool which is made of high speed steel and for Hollow ball head stud is used, at a deformation ratio of 60 ⁰ O, machine about 10,000 to 20,000 pieces in JIS · SCM-21 steel, but only about 2,000 to 5,000 pieces in JIS · SCM-4 steel. Incidentally, it is well known that a smaller difference in deformation resistance or flow resistance of the steel or alloy to be machined, especially when working with a high deformation ratio, has a considerable effect on the life of the tool and the efficiency of the manufacturing process, as mentioned above.

The most important features of the invention are summarized as follows:

Above all, a low-carbon steel or is according to the invention as a starting material uses a low-carbon alloy steel that is excellent at room temperature machinable, so that the molding process can be carried out more easily and efficiently at room temperature. Farther is a relatively low carburizing carbon content of the surface carburizing layer, for example about 0.6%, with a relatively small surface carburization thickness of about 0.3 to 0.5 mm provided; the selected diffusion treatment temperature is just as high as the carburization quenching or curing temperature, so that due to the improved excellent curing effect gives a hardness structure sufficiently good for a low-carbon steel; the remuneration treatment becomes at the tempering temperature used for a common carbon steel performed so that the mechanical properties, such as toughness or ductility.

Fatigue limit. Tensile or breaking strength, shock load resistance, Load capacity and the like can be remarkably improved. Eventually, the high frequency induction hardening process becomes only applied to the spherical part of the spherical head bolt, whereby a spherical head bolt is produced leaves, which is excellent despite its low carburization depth and its low carbon content Has properties with regard to the wear-resistant wedge and the ductility. Beyond that by the method according to the invention for producing the ball head bolt for the manufacture! Treatment process shortens the time required and significantly reduces the manufacturing cost. That invented Appropriate heat treatment processes can also be used be used for the manufacture of an article or part, in which for a limited part this article a characteristic wear resistance and at the same time for the remaining part this Article has a special toughness and strength that is required, as is the case with valves, for example plungers, valve adjusting screws and the like are the case with internal combustion engines for use reach.

Table 1

12th

Characteristic properties of the ball head bolts produced according to the invention compared to those according to

the known processes

Characteristic properties

Heat treatment process according to the invention

1. Procedure
(exercised in Japan)

Treatment method
State of the art

2. Procedure
(exercised in Japan)

3. Procedure (exercised in USA)

Material quality (main components) (° / o)

Treatment process after cold working

Tensile strength of the screw bolt part (on: kg / mm =)

Yield strength of the screw bolt (a _s : kg / mm ² )

Tensile strength of the shaft part (<7 _ß : kg / mm ² )

Yield point (o _s : kg / mm ² ) elongation (σ: ⁰ Zo)

Surface carbon concentration (° / o)

Metal structure
and
other
conditions

Carburization depth (mm)

Hardness (HRc)

Bullet

Shaft and
Bolt

surface

Inner part

surface

Inner part

JISSCM-21 C: 0.15
Cr: 0.9
Mo: 0.20

Carburization hardening (900 ° C)

Quenching and tempering (42O ⁰ C) -high frequency induction hardening -> quenching and tempering at low temperature (200 ° C)

12O ~ 13O
110 ~ 120
UO 120

80 90

18 19

0.5 to 0.7

0.3 to 0 _; 6th

62 to 63
Martensite (Fig. 8)

Sorbitol + troostite + ferrite (Fig. 9)

Sorbitol (Fig. 14)

JISSCM-21
C: 0.4
Cr: 0.9
Mo: 0.2

Editing the
Spherical surface
- ^ - hardening
(850 C) - ^ quenching and tempering (580 ^D C)
- High frequency induction hardening
- ^ - remuneration at
low temperature (200 ° C)

110 ~ 120

90 ~ 110
UO 120

110
19th

up to 60
Martensite (Fig. 8)

Sorbitol (Fig. 11)

Sorbitol (Fig. 11)

Sorbitol + Troostit + - a smaller amount of ferrite (Fig. 15)

Sorbitol (Fig. 11)

JISSCM-21
C: 0.16
Cr: 0.9

Mo: 0.2

Carburization protection - »■ Carburization (900 ° C)
- Diffusion hardening (35O ° C)
• Remuneration at
low temperature (200 ° C)
- * removal of the
Carburization protection

90 ~ 100

65 ~ 75
95

65
19th
0.7 to 0.9

0.5 to 0.8

up to 64

Martensite + rest
Austenite (Fig. 12)

Ferrite + stroostite
+ a smaller one
Amount of martensite
(Fig. * 13)

Ferrite - Troostite
a smaller one
Amount of martensite
(Fig. 13)

Ferrite + troostite
a smaller one
Amount of martensite
(Fig. 13)

corresponding to JISSCM-21 C: 0.2
Cr: 0.5
Ni: 0.5
Mo: 0.2

Carburization ( ⁰

Diffusion hardening (850 ° C) - * tempering at low temperature (200 ° C) -v high frequency induc tempering of the thread - ► Air cooling

90 ^ 100

60 ^ 75
90 95

60 65
18 19
0.7 to 0.9

0.5 to 0.8

62 to 64

Martensite + rest of austenite (Fig. 12]

Ferrite + Troostit -J- a smaller one Amount of martensite (Fig. 13)

Thread part: sorbitol (Fig. 14), shaft part: ferrite

Troostite

Martensite (Fig. 16)

Ferrite + Troostite + a smaller amount of Martensii (Fig. 17)

2 165 1Ü5

13th Height of fall (mm)
one on the
spherical part
impinging
30 kg weight
before generation
a break Heat treatment
proceed according to
the invention 1. Procedure
(exercised in Japan) 14th 1
3. Procedure
(in USA ex Characteristic properties Height of fall (mm)
one on the
spherical part
impinging
30 kg weights E.
before generation
of a strong one
Break 35 to 40 28 to 34 Prosecutor
State of the art
2. Procedure
(exercised in Japan) 28 to 32 Hardness of the inner part (HRc) 2, 700 kg 2,000 kg 28 to 32 1,800 kg 6th Flexural strength of the conical
Part of the shaft, loaded on
of the sphere (fracture generation:
Fig. 5 b) 700,000 cycles 100,000 cycles 1,800 kg 69,000 cycles 7th Fatigue strength (bending)
( ^p max ^of fracture generation:
1000 kg cycle, P _mi ": 100 kg) 1,200 1,000 60,000 cycles 260 8th Firm
speed
against
above
Push and
Blow 71,500 1,500 360 1,000 1,200

The steels listed above in detail in the form of abbreviations have the following compositions Settlements on:

Composition ( ⁿ / o)

C. Si Mn Ni Cr Mon P. S. S-15 C (JISS-15C) .... 0.10-0.20 - 0.30-0.60 - - - S-20C 0.15-0.25 0 30-0 60 SCM-21 (JIS-SCM-21) .. 0.13-0.18 0.15-0.35 0.60-0.85 0.90-1.20 0.15-0.35 SCM-22 0.18-0.23 0.15-0.35 0.60-0.85 0.90-1.20 0.15-0.35 SCM-23 0.17-0.23 0.15-0.35 0.60-0.85 0.90-1.20 0.15-0.35 SCM-4 (JIS · SCM-4) ... 0.38-0.43 0.15-0.35 0.60-0.85 0.90-1.20 0.15-0.35 0.030 0.030 SNCM-21 0.17-0.23 0.15-0.35 0.60-0.90 0.40-0.70 0.40-0.65 0.15-0.35 Max Max SNCM-22 0.12-0.18 0.15-0.35 0.40-0.70 1.60-2.00 0.40-0.65 0.15-0.35 SNCM-23 0.17-0.23 0.15-0.35 0.40-0.70 1.60-2.00 0.40-0.65 0.15-0.35 SNCM-24 0.17-0.23 0.15-0.35 0.70-1.10 2.80-3.40 1.50-2.00 0.30-0.50 SNCM-25 0.12-0.18 0.15-0.35 0.30-0.60 4.00-4.50 0.70-1.00 0.15-0.30 SNCM-26 0.13-0.20 0.15-0.35 0.80-1.20 2.80-3.20 1.40-1.80 0.40-0.70

In addition 8 sheets of drawings

Claims (3)

used. This ball head bolt made of low-alloy carbon steel is generally denied claims: quenched or hardened and then tempered. Ultimately, only the spherical part of the spherical head bolt is re-opened at a relatively lower temperature. 1. Process for the production of a ball head by high-frequency induction heat treatment studs made of carbon steel or alloy steel, case-hardened and tempered,
through successive carburization quenching or case hardening, Di.Tusions-. treatment, cause or remuneration treatment io and high frequency induction hardening treatment, 2. Second method which only apply to the spherical part of the
Ball head bolt is limited, thereby k e η η ζ e i c h η e t that as a starting material a case-hardened or a case-hardened steel with Carbon steel with 0.13 to 0.18 ° / oC, 0.9 to 15 a carbon content of 0.15 to 0.23% is defined as 1.2 ⁰ OCr, less than 0.30 ¹ VoNi, 0.15 to 0 , 30 °. 0 starting material is used and all parts except Mo, 0.15 to 0.35 ° / oSi, 0.60 to 0.85 ⁰ ViMn, and the spherical part of the ball head bolt is used with-remainder iron, that the carburetel a Copper plating or other suitable temperature hardening treatment means given a carburization preventive treatment; from 890 to 920 C is carried out, that the ao after that the case hardening and the long-term diffusion treatment are carried out at one of the temperature tempering treatment at a low temperature of the carburization hardening treatment about temperature. Finally, the layers formed by the speaking temperature are carried out that the anti-carburization treatment removes the tempering or tempering treatment at one.
Temperature is carried out above 430 ° C and 35
that the high frequency induction hardening treatment ment exclusively on the spherical part of the third third procedure Ball head bolt is limited. 2. The method according to claim 1, characterized ge indicates that in the carburized upper 30 A case-hardening steel with a carbon content of surface layer of the ball head bolt a carbon 0.15 to 0.23% is used as the starting material for the siofTgchalt set between 0.5 and 0.7 "/ 0 ball head bolts are used. at a low temperature, the surface becomes 3. The method according to claim 1 or 2, characterized in set hardening treatment and a long-term Vergado, that the depth of carburization of the 35 processing treatment subjected, after which the with a Ball head bolt set to 0.3 to 0.6 mm threaded part of the ball head bolt through will. the high frequency induction heat treatment driving is remunerated and then slowly cooled down. The three known methods described above 40 have different advantages as well as different, disadvantages described below, i. i.e., according to The first method is a low alloy steel with more than 0.4O ⁰ ZoC used to make a pretty