CA1076395A - Substantially silver free brazing alloys - Google Patents
Substantially silver free brazing alloysInfo
- Publication number
- CA1076395A CA1076395A CA322,136A CA322136A CA1076395A CA 1076395 A CA1076395 A CA 1076395A CA 322136 A CA322136 A CA 322136A CA 1076395 A CA1076395 A CA 1076395A
- Authority
- CA
- Canada
- Prior art keywords
- cobalt
- free brazing
- shank
- substantially silver
- zinc
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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- Earth Drilling (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Substantially silver-free brazing alloys are provided which are suitable for use in the fabrication of cutting tools, for example, the braz-ing of a cutting tip to a shank of a rock drill. One particular substantially silver-free brazing alloy in accordance with an aspect of this invention com-prises, apart from impurities, 10-45 wt.% zinc, 0.2-.5 wt.% manganese; 0,2-10 wt.% nickel; 0.2-10 wt.% cobalt; and balance copper. This substantially silver-free brazing alloy possesses the ability to wet steel (the shank material) and a cobalt-bonded tungsten carbide (the cutting tip material) while being metallurgically compatible with both these materials.
Substantially silver-free brazing alloys are provided which are suitable for use in the fabrication of cutting tools, for example, the braz-ing of a cutting tip to a shank of a rock drill. One particular substantially silver-free brazing alloy in accordance with an aspect of this invention com-prises, apart from impurities, 10-45 wt.% zinc, 0.2-.5 wt.% manganese; 0,2-10 wt.% nickel; 0.2-10 wt.% cobalt; and balance copper. This substantially silver-free brazing alloy possesses the ability to wet steel (the shank material) and a cobalt-bonded tungsten carbide (the cutting tip material) while being metallurgically compatible with both these materials.
Description
1al7639S
This invention relates ~o alloys and especially to substantially silver-free brazing alloys~
This application iS a divisional of application Serial No. 218, 574 filed Jan. 24, 19-75.
- ~ brazing alloy for use in forming a brazed joint between the shank and cutting tip of a rock drill should ideally possess the ability to `
wet steel ~the shank material) and a cobalt-bonded tungsten carbide (the cutting tip material) as well as being metallurgically compatible with these materials, A brazing alloy should be of relatively low intrinsic cost and have the ability to be fabricated in the form of a wire and strip by standard production methods. A bra~ing alloy should also possess a relative-ly high plasticity in a temperature range between the solidus of the brazing alloy and, ssy, 300C. This plasticity feature reduces the risk of cracking which tends to occur in large size drills during cooling due to the widely differing contraction chsracteristics of steel and tungsten carbides. Fur-ther, a brszing alloy should have a sufficiently high strength at room tem-perature, for example, a U.T.S. of 20-30 tons/square inch, to reduce the risk of premature failure of a drill due to fatigue of the brazed joint be-tween the shank and the tip.
It is an object of an aspect of this invention to provide a sub-stantially silver-free brazing alloy for use in the fabrication of cutting tools, for example, the brazing of a cutting tip or cutting insert on to a shank of a rock drill.
By a broad aspect of this invention, a substantially silver~free brazing alloy is provided comprising copper, zinc, manganese, cobalt, and, optionally nickel, the proportlon of zinc being 10-45 wt.%; the proportion of manganese being 0.2-15 Wt.%; the proportion of nickel being 0-10 wt.%;
the proportion of cobalt being 0.2-10 wt.%; wi~h the balance being copper.
By one variant, the alloy, apart from impurities, comprises: 10-45 wt.% zinc 0.2-15 wt.% manganese; 0.2-10 wt.% cobalt; and balance ~7639S
copper.
By another variant, the alloy, apart from impurities, comprises:
10-45 wt.~ zinc; 0.2-15 wt.% manganese; 0.2-10 wt.% cobalt; 0.2-10 wt.
nickel; and balance copper.
By yet another variant, the alloy, apart from impurities, consists essentially of 38 wt.% zinc; 2 wt.% manganese; 2 wt.% cobalt; and 58 wt.%
copper, such alloy melting within a temperature range of 890-930C.
By another aspect of this invention a cutting tool is provided having at least one cutting tip or at least one cutting insert secured to a shank of the tool by a substantially silver-~ree brazing alloy as described above in its various aspects and variants.
By yet another aspect of this invention, a rock drill is provided comprising: a steel shank; a groove in one end of said shank; a carbide cut-ting tip inserted in the groove; the dimensions of the ~roove providing a joint gap between the tip and the walls of the groove; and a substantialiy silver-free brazing alloy as described above in its various aspects and variants disposed in the joint gap and brazing the tip to the shaft.
By one variant thereof, the rock drill includes two or more cut-ting tips.
By another variant thereof, the joint gap is not less than 0.004 inch.
Reference has been made above to reducing the risk of cracking in brazed joints in carbide-tipped tools. This risk increases in proportion to the joint length which governs the magnitude of stresses produced by the di~erential contraction of the various materials present, . . " ,, :. .. : , -'' ' . .: . ~ ~ . '. -, . .
1~76395 namely, steel ( the drill shank), the brazing alloy, and tungsten carbide (the cutting tip).
The invention by the`present divisional application and in one of its variants will be hereinafter more fully described with reference to the accompanying drawing in which:
Figure 1 shows a side elevation of a drill fitted with a tungsten carbide insert showing the disposition of the brazing alloy of an aspect of this invention; and Figure 2 shows an end view of the drill seen in the direction of the arrow P of Figure 1.
As shown in the drawing, the drill 10 comprises a steel shank 12 formed at one end with a rectangular groove 14 in which is inserted a tung-sten carbide tip 16, the groove being dimensioned to provide a narrow gap 18 for receiving the brazing alloy forming the joint.
Brazing tests were carried out on rock drills with carbide tips 1.75 inch long (which is almost the maximum size used in industry) of the type shown in Figure 1.
Another factor affecting the risk of cracking is the joint gap width, rock drills with wider joint gaps being generally less susceptible to cracking under the influence of stresses due to differential contraction.
The width of the ~oint gap is quite an important factor and, generally speak-ing, the minimum admissible ~oint gap, that is, the smallest gap ensuring the freedom from crack formation during the cooling cycle of a brazing opera-tion, varies depending on the length of the carbide insert 16, the composi-tion of the steel shank 12 and on the cooling site after brazing.
The nominal ~oint gap in all the experimental rock drills brazed during this investigation was 0.004 inch. This figure is near the lowe~
limit of the ~oint gap range recommended for, and used in such brazed ~oints, and experience has shown that such a gap is sufficiently small to promote cracking ' .. : ' . ' . :
07639~
of joints with unsuitable alloys.
Each brazing test was carried out under conditions simulating the brazing cycle currently used in the manufacture of rock drills. In this pro-cedure the brazing operation is combined with the heat treatment of the steel shank. This is done by heating the workpiece to the brazing tempera-ture, cooling or heating it (as necessary) depending on the meltlng point of the alloy, to 850C, transferring it to an oven at 350C, holding it at 350C
for one hour, and then cooling it in air to room temperature.
To ascertain that tests carried out under the conditions chosen would provide a relible means of revealing the potential usefulness of the alloys tested, a preliminary ser~es of experiments was carried out with a Cu-2,5 Ni-0.6~ Si alloy referred to as "A" sronze", known to produce ~oints susceptible to cracking and with a ductile alloy Cu-3~Ni referred to as "B"
Bronze, known to produce crack-free joints (but not used in the manufacture of rock drills because of its low strength). Extensive cracks where, in fact, formed in joints made with "A" Bronze whereas little or no evidence of crack-ing was found in joints made with "B" Bronze. This was regarded as a sufficient proof of the reliability of the test.
Medium-frequency heating was used for brazing. Sufficient brazing alloy to form the joint was placed at the bottom of a wall of the groo~e formed in the steel shank of the rock drill. A coat of paste known by the Trade Mark of Tenacity No. 5 Flux paste was next applied to the joint area which was then sprinkled with a liberal quantity of boric oxide to increase the stability of the flux at elevated temperatures. Asbestos tape was wrapped round the drill to contain the molten flux in the joint gap.
The compositions of the alloys tested included various combinations of the constituents zinc, manganese, nickel, cobalt, copper and silicon, i.e., of substantially silver-free brazing alloys both within the scope of aspects of this invention, and outside the scope thereof. Zinc was used as melting , , point depressants; manganese was added to improve the wetting characteristics :
:. ;. . :
~07~3g5 of the alloys on tungsten carbide; cobalt and nickel(if desired) were intro-duced to act as hardeners to improve the joint filling properties of the alloys and to reduce the extent of erosion of tungsten carbide by molten braz-ing alloys, whilst silicon was added to improve the wettability and the flow characteristics of the alloys.
Typical of the large number of alloys tested are those referred to in Table 1 as Alloys Nos. 1, 2 and 3.
The melting ranges of the alloys tested were determined by spread-ing tests carried out in a continuous brazing furnace at temperatures pro-gressively increasing in steps of 20C.
The hardness of the alloys (in the as-cast condition and after a heat treatment simulating the brazing cycle) was measured to get a rough esti-mate of their relative strength.
Visual examination alone of joints in brazed rock drill specimens could not be relied on to determine the presence or extent of cracking ex-cept in the case of large open cracks visible on both the vertical and hori-zontal joint faces. In other cases there was a possibility of hair cracks being concealed as a result of the cleaning operation (sand blasting), or of surface defects.(e.g., solidification shrinkage) being mistaken for cracks.
It was, therefore, necessary to section the specimens for examination in the plane indicated by X - X in Figure 1. The results of the examination of specimens brazed with three of the alloys tested are given in Table 1.
From the results given in this Table it will be seen that neither of the alloys referred to as Nos. 1 and 2 produced crack-free ~oints under the experimental conditions used in this investigation. Similar results were obtained with all the other alloys tested apart from alloys according to aspects of this invention. These latter are exemplified by alloy No. 3 and gave very satisfactory results. The nominal compositions of alloy 3 as , . : .. - . .:,~,. . . . ,: . ,. , :
:::, :,: , ' : . . ,, -~C~76395 given in the table was:
58Cu-38ZD-2Mn-2Co (Melting range: 890-930C):
Kilogram quantities of these alloys were made as 3 mm diameter wire and 1 mm and 3 mm thick sheet. The materialg were fabricated without any difficulties by conventional methods (hot rolling followed by cold rolling and annealing) and further evaluation has shown them to be satisfactory bra~ing alloys.
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This invention relates ~o alloys and especially to substantially silver-free brazing alloys~
This application iS a divisional of application Serial No. 218, 574 filed Jan. 24, 19-75.
- ~ brazing alloy for use in forming a brazed joint between the shank and cutting tip of a rock drill should ideally possess the ability to `
wet steel ~the shank material) and a cobalt-bonded tungsten carbide (the cutting tip material) as well as being metallurgically compatible with these materials, A brazing alloy should be of relatively low intrinsic cost and have the ability to be fabricated in the form of a wire and strip by standard production methods. A bra~ing alloy should also possess a relative-ly high plasticity in a temperature range between the solidus of the brazing alloy and, ssy, 300C. This plasticity feature reduces the risk of cracking which tends to occur in large size drills during cooling due to the widely differing contraction chsracteristics of steel and tungsten carbides. Fur-ther, a brszing alloy should have a sufficiently high strength at room tem-perature, for example, a U.T.S. of 20-30 tons/square inch, to reduce the risk of premature failure of a drill due to fatigue of the brazed joint be-tween the shank and the tip.
It is an object of an aspect of this invention to provide a sub-stantially silver-free brazing alloy for use in the fabrication of cutting tools, for example, the brazing of a cutting tip or cutting insert on to a shank of a rock drill.
By a broad aspect of this invention, a substantially silver~free brazing alloy is provided comprising copper, zinc, manganese, cobalt, and, optionally nickel, the proportlon of zinc being 10-45 wt.%; the proportion of manganese being 0.2-15 Wt.%; the proportion of nickel being 0-10 wt.%;
the proportion of cobalt being 0.2-10 wt.%; wi~h the balance being copper.
By one variant, the alloy, apart from impurities, comprises: 10-45 wt.% zinc 0.2-15 wt.% manganese; 0.2-10 wt.% cobalt; and balance ~7639S
copper.
By another variant, the alloy, apart from impurities, comprises:
10-45 wt.~ zinc; 0.2-15 wt.% manganese; 0.2-10 wt.% cobalt; 0.2-10 wt.
nickel; and balance copper.
By yet another variant, the alloy, apart from impurities, consists essentially of 38 wt.% zinc; 2 wt.% manganese; 2 wt.% cobalt; and 58 wt.%
copper, such alloy melting within a temperature range of 890-930C.
By another aspect of this invention a cutting tool is provided having at least one cutting tip or at least one cutting insert secured to a shank of the tool by a substantially silver-~ree brazing alloy as described above in its various aspects and variants.
By yet another aspect of this invention, a rock drill is provided comprising: a steel shank; a groove in one end of said shank; a carbide cut-ting tip inserted in the groove; the dimensions of the ~roove providing a joint gap between the tip and the walls of the groove; and a substantialiy silver-free brazing alloy as described above in its various aspects and variants disposed in the joint gap and brazing the tip to the shaft.
By one variant thereof, the rock drill includes two or more cut-ting tips.
By another variant thereof, the joint gap is not less than 0.004 inch.
Reference has been made above to reducing the risk of cracking in brazed joints in carbide-tipped tools. This risk increases in proportion to the joint length which governs the magnitude of stresses produced by the di~erential contraction of the various materials present, . . " ,, :. .. : , -'' ' . .: . ~ ~ . '. -, . .
1~76395 namely, steel ( the drill shank), the brazing alloy, and tungsten carbide (the cutting tip).
The invention by the`present divisional application and in one of its variants will be hereinafter more fully described with reference to the accompanying drawing in which:
Figure 1 shows a side elevation of a drill fitted with a tungsten carbide insert showing the disposition of the brazing alloy of an aspect of this invention; and Figure 2 shows an end view of the drill seen in the direction of the arrow P of Figure 1.
As shown in the drawing, the drill 10 comprises a steel shank 12 formed at one end with a rectangular groove 14 in which is inserted a tung-sten carbide tip 16, the groove being dimensioned to provide a narrow gap 18 for receiving the brazing alloy forming the joint.
Brazing tests were carried out on rock drills with carbide tips 1.75 inch long (which is almost the maximum size used in industry) of the type shown in Figure 1.
Another factor affecting the risk of cracking is the joint gap width, rock drills with wider joint gaps being generally less susceptible to cracking under the influence of stresses due to differential contraction.
The width of the ~oint gap is quite an important factor and, generally speak-ing, the minimum admissible ~oint gap, that is, the smallest gap ensuring the freedom from crack formation during the cooling cycle of a brazing opera-tion, varies depending on the length of the carbide insert 16, the composi-tion of the steel shank 12 and on the cooling site after brazing.
The nominal ~oint gap in all the experimental rock drills brazed during this investigation was 0.004 inch. This figure is near the lowe~
limit of the ~oint gap range recommended for, and used in such brazed ~oints, and experience has shown that such a gap is sufficiently small to promote cracking ' .. : ' . ' . :
07639~
of joints with unsuitable alloys.
Each brazing test was carried out under conditions simulating the brazing cycle currently used in the manufacture of rock drills. In this pro-cedure the brazing operation is combined with the heat treatment of the steel shank. This is done by heating the workpiece to the brazing tempera-ture, cooling or heating it (as necessary) depending on the meltlng point of the alloy, to 850C, transferring it to an oven at 350C, holding it at 350C
for one hour, and then cooling it in air to room temperature.
To ascertain that tests carried out under the conditions chosen would provide a relible means of revealing the potential usefulness of the alloys tested, a preliminary ser~es of experiments was carried out with a Cu-2,5 Ni-0.6~ Si alloy referred to as "A" sronze", known to produce ~oints susceptible to cracking and with a ductile alloy Cu-3~Ni referred to as "B"
Bronze, known to produce crack-free joints (but not used in the manufacture of rock drills because of its low strength). Extensive cracks where, in fact, formed in joints made with "A" Bronze whereas little or no evidence of crack-ing was found in joints made with "B" Bronze. This was regarded as a sufficient proof of the reliability of the test.
Medium-frequency heating was used for brazing. Sufficient brazing alloy to form the joint was placed at the bottom of a wall of the groo~e formed in the steel shank of the rock drill. A coat of paste known by the Trade Mark of Tenacity No. 5 Flux paste was next applied to the joint area which was then sprinkled with a liberal quantity of boric oxide to increase the stability of the flux at elevated temperatures. Asbestos tape was wrapped round the drill to contain the molten flux in the joint gap.
The compositions of the alloys tested included various combinations of the constituents zinc, manganese, nickel, cobalt, copper and silicon, i.e., of substantially silver-free brazing alloys both within the scope of aspects of this invention, and outside the scope thereof. Zinc was used as melting , , point depressants; manganese was added to improve the wetting characteristics :
:. ;. . :
~07~3g5 of the alloys on tungsten carbide; cobalt and nickel(if desired) were intro-duced to act as hardeners to improve the joint filling properties of the alloys and to reduce the extent of erosion of tungsten carbide by molten braz-ing alloys, whilst silicon was added to improve the wettability and the flow characteristics of the alloys.
Typical of the large number of alloys tested are those referred to in Table 1 as Alloys Nos. 1, 2 and 3.
The melting ranges of the alloys tested were determined by spread-ing tests carried out in a continuous brazing furnace at temperatures pro-gressively increasing in steps of 20C.
The hardness of the alloys (in the as-cast condition and after a heat treatment simulating the brazing cycle) was measured to get a rough esti-mate of their relative strength.
Visual examination alone of joints in brazed rock drill specimens could not be relied on to determine the presence or extent of cracking ex-cept in the case of large open cracks visible on both the vertical and hori-zontal joint faces. In other cases there was a possibility of hair cracks being concealed as a result of the cleaning operation (sand blasting), or of surface defects.(e.g., solidification shrinkage) being mistaken for cracks.
It was, therefore, necessary to section the specimens for examination in the plane indicated by X - X in Figure 1. The results of the examination of specimens brazed with three of the alloys tested are given in Table 1.
From the results given in this Table it will be seen that neither of the alloys referred to as Nos. 1 and 2 produced crack-free ~oints under the experimental conditions used in this investigation. Similar results were obtained with all the other alloys tested apart from alloys according to aspects of this invention. These latter are exemplified by alloy No. 3 and gave very satisfactory results. The nominal compositions of alloy 3 as , . : .. - . .:,~,. . . . ,: . ,. , :
:::, :,: , ' : . . ,, -~C~76395 given in the table was:
58Cu-38ZD-2Mn-2Co (Melting range: 890-930C):
Kilogram quantities of these alloys were made as 3 mm diameter wire and 1 mm and 3 mm thick sheet. The materialg were fabricated without any difficulties by conventional methods (hot rolling followed by cold rolling and annealing) and further evaluation has shown them to be satisfactory bra~ing alloys.
~0763g~
~ . e 1~ ~ N
C U
O
u~ a~
O U~
~ ~ O
~' O O
1. ~ o~ ~
C~
ยข z ,, t~l ,' ~
', ' ~' . : ` : `
Claims (8)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A substantially silver-free brazing alloy comprising:
an alloy of copper, zinc, manganese, cobalt, and, optionally nickel;
wherein the proportion of zinc is 10-45 wt.%;
wherein the proportion of manganese is 0.2-15 wt.%;
wherein the proportion of nickel is 0-10 wt.%;
wherein the proportion of cobalt is 0.2-10 wt.%;
and wherein the balance is substantially copper.
an alloy of copper, zinc, manganese, cobalt, and, optionally nickel;
wherein the proportion of zinc is 10-45 wt.%;
wherein the proportion of manganese is 0.2-15 wt.%;
wherein the proportion of nickel is 0-10 wt.%;
wherein the proportion of cobalt is 0.2-10 wt.%;
and wherein the balance is substantially copper.
2. A substantially silver-free brazing alloy as claimed in claim l, and, apart from impurities, comprising: 10-45 wt.% zinc; 0.2-15 wt.%
manganese; 0.2-10 wt.% cobalt; and balance copper.
manganese; 0.2-10 wt.% cobalt; and balance copper.
3. A substantially silver-free brazing alloy as claimed in claim 1 and, apart from impurities, comprising: 10-45 wt.% zinc; 0.2-15 wt.% man-ganese; 0.2-10 wt.% cobalt; 0.2-10 wt.% nickel; and balance copper.
4. A substantially silver-free brazing alloy according to claim 1 and apart from impurities consisting essentially of: 38 wt.% zinc; 2 wt.%
manganese; 2 wt.% cobalt; and 58 wt.% copper.
manganese; 2 wt.% cobalt; and 58 wt.% copper.
5. A cutting tool having at least one cutting tip or at least one cutting insert secured to a shank of the tool by substantially silver-free brazing alloy as claimed in claims 2, 3 or 4.
6. A rock drill comprising: a steel shank; a groove in one end of said shank; a carbide cutting tip inserted in said groove; the dimensions of said groove providing a joint gap between said tip and the walls of said groove; and a substantially silver-free brazing alloy as claimed in claim 1 disposed in said joint gap and brazing the tip to the shank.
7. A rock drill according to claim 6 including two or more cutting tips.
8. A rock drill according to claims 6 or 7, wherein the joint gap is not less than 0.004 inch.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA322,136A CA1076395A (en) | 1974-01-24 | 1979-02-23 | Substantially silver free brazing alloys |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB334374A GB1462661A (en) | 1974-01-24 | 1974-01-24 | Brazing alloy |
| CA218,574A CA1071439A (en) | 1974-01-24 | 1975-01-24 | Brazing alloy |
| CA322,136A CA1076395A (en) | 1974-01-24 | 1979-02-23 | Substantially silver free brazing alloys |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1076395A true CA1076395A (en) | 1980-04-29 |
Family
ID=27163793
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA322,136A Expired CA1076395A (en) | 1974-01-24 | 1979-02-23 | Substantially silver free brazing alloys |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1076395A (en) |
-
1979
- 1979-02-23 CA CA322,136A patent/CA1076395A/en not_active Expired
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