Some standard content:
MT/T789--1998
The diamond core drill bit for coalfield drilling consists of four parts: ordinary single-tube diamond drill bit, ordinary double-tube drill bit, rope core drill bit, and large-diameter engineering drill bit. Among them, ordinary single-tube drill bit and ordinary double-tube drill bit are divided into two series, A and B. Series A is equivalent to the content of the diameter above 75mm in the national standard "Diamond Core Drilling Equipment". When the domestic market can supply matching drill pipes, it is advisable to give priority to this standard series; Series B is the drill bit series currently used in actual production, referring to DZ2.1 "Diamond Drill Bit for Geological Drilling". Before Series A can be put into practical use, it can be selected by users. After Series A is put into practical use, Series B should be revised or abolished.
This standard is proposed by the Industry Management Department of the State Administration of Coal Industry. This standard is under the jurisdiction of the Coal Industry Coal Mine Special Equipment Standardization Technical Committee. This standard was drafted by the Xi'an Branch of the China Coal Research Institute. The main drafters of this standard are Li Yue and Mou Zhaohua. This standard is entrusted to Xi'an Branch of China Coal Research Institute for interpretation. 78
1 Scope
Coal Industry Standard of the People's Republic of China
Diamond core bit for coal drilling
Diamond core bit for coal drillingMT/T 789-1998
This standard specifies the types and parameters, technical requirements, test methods, inspection rules, marking and packaging of diamond core bits with a diameter of 75mm or more for coal drilling. This standard is applicable to diamond core bits (hereinafter referred to as drill bits) for rotary and impact rotary drilling of holes with a diameter of 75mm or more for coalfield geology, engineering construction, underground gas extraction, water injection and drainage in coal mines. 2 Referenced standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard was published, the versions shown were all valid. All standards are subject to revision. Parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T228-1987 Metal tensile test method
GB3423-1982 Diamond core drilling seamless steel pipe GB6407—1986 Synthetic diamond technical conditions GB/T13264--1991 Small batch counting sampling inspection procedures and sampling tables for non-conforming rate DZ1.5--1986 Geological core drilling pipe thread detection method DZ2.1--1987 Geological drilling diamond drill bit JB3233-1983 Drilling synthetic diamond sintered body 3 Types and parameters
3.1 Drill bit series, type and code regulations. The series, type and code of the drill bit should comply with the provisions of Table 1 and Table 2. 3.1.14
Drill bit type
A series
Type code
Drill bit diameter, mm
B series
Drill bit type
Type code
Ordinary single-tube drill bit
Ordinary single-tube
Ordinary double-tube
3.1.2 The diamond setting form and code of the drill bit shall be in accordance with the provisions of Table 3. 3.2 The lip shape of the drill bit should adopt the standard form of Figure 1 and Table 4. Approved by the State Coal Industry Bureau on November 10, 1998 N
Ordinary double-tube drill
Rope coring
Engineering thin wall
Implemented on April 1, 1999
Natural surface setting
Flat-bottomed lip
Fully circular lip
Semi-circular lip
Semi-flat lip
Single-step lip
Multi-step lip
Concentric sharp tooth lip
Staggered high and low sharp tooth lip
Step-tip mixed lip| |tt||3.3 Rules for indicating drill bit models
MT/T789-1998
Natural impregnation
Artificial single crystal impregnation
Sawtooth face
Bottom spray face
Guide bottom spray lip face
Staggered lip face
Staggered high and low tooth lip face
Double cone lip face
Curved shallow dimensional angle lip face
Manufactured bevel lip facebZxz.net
The drill bit model is indicated by letters, numbers and symbols representing given meanings arranged in a certain color sequence. A series:
Drill bit type code
Example: NS is a single tube drill bit with a diameter of 75mm. B series:
Drill diameter code
Artificial polycrystalline
MT/T789-1998
-Drill inner diameter, mm
Drill outer diameter, mm
Lip shape code
Drill type code
Diamond setting form code
Example: TBPC95/68 is a natural diamond surface-set ordinary double-tube semicircular lip drill with an outer diameter of 95mm and an inner diameter of 68mm. 3.4 Parameter series
3.4.1A series
3.4.1.1S-type ordinary single-tube drill bits shall comply with the provisions of Figure 2 and Table 5. 158
Specifications and dimensions
3.4.1.2P-type ordinary double-tube drill bits shall comply with the provisions of Figure 3 and Table 6. Di
Specification size
3.4.2B series
MT/T789—1998
Ordinary double-tube drill bits shall comply with the provisions of Figure 4 and Table 7. H
Outer diameter d
Inner diameter DOuter diameter d'
[Inner diameter D'
54.5±8:1
Thread size
68.5+8 0867. 0+. 05
Ordinary single-tube drill bits shall comply with the provisions of Figure 5 and Table 8. h14
Quantity (pcs)
8～10
10～12
10～14
Specifications (width x height)
(depth x width)
(4～6)×l
(4～6)
(4~～6)
Outer diameter d
Inner diameter D
Outer diameter d'
Inner diameter D
54.5±8173±0.1
74±8:2
93 ±8:2
133±8:1
133±8:2
[110±0.1
MT/T789--1998
Thread size
68.5-8:19
67.0二8:22
84=8:18
103-8:19
122二8:18
141-8:22
1.60-0.10
Rope coring The drill bit should comply with the requirements of Figure 6 and Table 982.5=8:2
101,.5=8:12
120.5-8:29
139.5=8:22
Outer diameter d
Inner diameter DOuter diameter d'
62±8:1
Inner diameter D
Thread size
68.5+8.0867.0+8.05
84+9:06
82.5+g.05
Quantity (pieces)
10~12
12~~14
14~~16
16~18
10~~14
Specifications (width and height)
(depth×width)
( 4～6)×
12～16
14～16
20～22
Quantity (pieces)
8～10
10～14
10～14
(6~7) ×
(4～6)
(6~8)(6~7)
Specifications (width×height)
(3~~6)×
(depth×width)
MT/T 789--1998
3.4.2.4 Large-diameter engineering drill bits shall comply with the requirements of Figure 7 and Table 10. H | | tt | ±0.2
114-:1
133±0.3150±0.2135±81
173+8:1
150±0.3170±0.2
193193±0.4170±0.3190
152±8:.1
213213±0.4187±0.3210±0.2
4 Technical requirements
4.1 Diamond drill bit
Thread size
101.5=8.8
122=8:.16
139.5=8:98| |tt||160-8：8
Quantity (pcs)
10～12
12～14
Specifications (width×height)
(5~9)×
16～20
14~～18
4.1.1 The technical requirements for artificial diamond single crystals for drill bits shall comply with the provisions of GB6407. 28
4.1.2 The size, shape and technical requirements for artificial diamond polycrystals for drill bits shall comply with the provisions of JB3233. The requirements for the grade of natural diamonds for drill bits shall comply with the provisions of Table 11. 4.1.3
High-quality grade
Standard grade
Natural crystal or hazy ring, bright, pure, without spots and inclusions, without cracks, no limit on tremolo color, dodecahedron content of 35%~90%, octahedron content of 10%~65% The crystal is regular and complete, relatively round, dodecahedron content of 15%~20%, octahedron content of 80%~85%, each grain should have no less than 4~6 good sharp knives, no limit on tremolo color, no cracks, no inclusions
The grains are regular and complete, with octahedral complete grains reaching 90% to 95%. Each grain should have no less than 4 sharp edges, ranging from bright and transparent to dull luster 6×2.5
(6～9)X
(depth×width)
Drill bit or rope for drilling hard formations
Coring drill bit
Drill bit or rope for drilling hard formations
Coring drill bit
Drill bit for drilling medium-hard to hard formations
External grade
MT/T 789--1998
Continued Table 11
Octahedral complete grains reach 30%40%, some spotted inclusions are allowed, the color is light yellow to dark gray, or small complete diamond grains or round block-shaped particle fragments after rounding treatment, continuous crystals are crushed for use, and there is no crystal
4.2 Drill bit steel body material
Drill bits for drilling medium-hard formations
Imperforated drill bits
The mechanical properties and welding properties of the drill bit steel body material shall not be lower than the corresponding indicators of DZ40 in GB3423. 4.3 Drill bit matrix
The wear resistance of the matrix shall comply with the provisions of Table 12. 4.3.1
Wear resistance indication
ML(X10-5)
4.3.2 The erosion resistance of the matrix shall comply with the provisions of Table 1.3. Erosion resistance index
z(1/cm2)
4.3.3 The linear expansion coefficient of the matrix shall comply with the provisions of Table 14. Cold pressing method, non-pressing method
Hot pressing method
(9~13)×10-5(1/℃)
(12~15)×10-5(1/C)
The matrix hardness shall be selected according to the hardness and abrasiveness of the rock in accordance with the range listed in Table 15. 4.3.4
Matrix type
Matrix hardness (HRC)
4.3.5 Flexural strength
35～45
Using standard test blocks for inspection, the flexural strength of the matrix manufactured by hot pressing and cold pressing methods shall not be less than 800MPa, and the flexural strength of the matrix manufactured by non-pressing method shall not be less than 600MPa.
4.3.6 Metallographic requirements
The specimen shall be observed under a metallographic microscope. The skeleton metal and bonding metal shall be evenly distributed, and the porosity of the matrix shall not exceed 0.6%. 4.3.7 Impact toughness
Tested with a standard test block, the matrix impact toughness shall not be less than 3J/cm2. 4.4 Finished drill bits
4.4.1 The drill bit specifications and dimensions shall comply with the provisions of Chapter 3 of this standard. 4.4.2
The drill bit matrix shall be observed under a 10x magnifying glass. There shall be no cracks at the connection between the matrix and the steel body and in the matrix itself. The coaxiality of the drill bit matrix outer circle and the thread and the perpendicularity of the matrix end face and the thread shall comply with the provisions of Table 16. 4.4.3
Drill bit nominal diameter
75~113
120~~213
MT/T 789—1998
Coaxiality tolerance
Verticality tolerance
4.4.4 The diamond distribution of impregnated drill bits should be uniform. The uniformity is determined by comparing the diamond exposure of each sector block on the same cross section with the average diamond exposure of the sector block. The error shall not exceed ±25%. 4.4.5 The diamonds of the surface-mounted drill bit should be evenly distributed on the lip surface, and the amount of cutting edge should be 1/4~1/3 of the diameter of the diamond particles. The diamonds should be placed correctly, the number of dislocated particles should not exceed 10%, 80% of the diameter-guaranteed diamonds should be visible, the diamonds should be firmly encased, and the number of threshing should not exceed 1%. 4.4.6 The hardness of the drill bit matrix should be selected according to the range specified in Table 15, and the deviation between the matrix hardness and the selected value should not exceed HRC3. The hardness of the drill bit matrix should be uniform, and the deviation between the hardness value of each measuring point of the same drill bit and its average value should not exceed HRC5. 4.4.7 The bonding strength between the drill bit matrix and the steel body shall be based on the 75 ordinary double-tube drill bit, and the bearing torque shall not be less than 150N·m. 4.4.8 The drill bit shall be surface treated, the surface shall be smooth, and the sprue and sink shall be smooth and unobstructed. 5 Test methods
5.1 The wear resistance, erosion resistance, linear expansion coefficient, bending strength and impact toughness of the drill bit matrix shall be measured in accordance with the provisions of DZ 2.1.
5.2 The mechanical properties of the drill bit steel body shall be measured in accordance with the provisions of GB/T 228. 5.3 The connection between the drill bit matrix and the steel body shall be inspected by visual inspection and observed under a 10x magnifying glass when necessary. 5.4 The inner diameter, outer diameter, height and other dimensions of the drill bit shall be measured with a vernier caliper with an accuracy of 0.02mm. 5.5 The measurement of the drill bit connection thread shall be carried out in accordance with the provisions of DZ1.5. 5.6 The coaxiality of the drill bit matrix outer circle and the thread, and the perpendicularity of the matrix end face and the thread shall be measured on the runout meter (or V-type bracket) using a threaded spindle (or threaded ring) and a dial indicator.
5.7 The diamond distribution of the surface-set drill bit is tested by the self-test method, and the diamond cutting amount is observed by a reading microscope. Ten points are randomly checked by the equal division method and the average value is taken.
5.8 The uniformity of the diamond distribution of the impregnated drill bit is determined by grinding the cutting edge with a flat grinding wheel, taking the fan-shaped block as a unit, and comparing it with the average cutting amount of each fan-shaped block on the same cross section, and taking a photo under a microscope for comparison. 5.9 The drill bit matrix hardness is measured on the outer side of the drill bit matrix that does not contain diamonds. Three points (roughly evenly distributed) are randomly selected for the same drill bit, and 5 drill bits are randomly selected for batch drill bits.
6 Inspection rules
6.1 Factory inspection,
6.1.1 Each product must be inspected before leaving the factory. The product must be inspected and qualified by the quality inspection department of the manufacturer, and can only be shipped with a product certificate.
6.1.2 The drill bit product should be inspected according to the items listed in Table 17 before leaving the factory. Table 17
Inspection items
Appearance requirements
Drill bit size
Defects of the carcass and its connection with the steel body
Bond strength between the carcass and the steel body
Carcass hardness
Factory inspection
Type inspection
Thread requirements
Inspection items
Diamond distribution of set drill bits
Diamond distribution of surface set drill bits
Diamond performance requirements
Carcass performance requirements
Note: “√” indicates a mandatory inspection item.
MT/T789--1998
Continued Table 17
Factory Inspection
6.1.3 All items of factory inspection must comply with the provisions of this standard. Products with unqualified items shall not be shipped. 6.2 Type Inspection
6.2.1 Type inspection shall be carried out in any of the following situations: a) Trial production and identification of new products or old products transferred to the factory for production; Type inspection
b) When the design, process, production equipment, management and other aspects of the products in normal production have major changes that may affect the product performance; c) During normal production, it shall be carried out every 3 years; d) When production is resumed after stopping production for 1 year; e) When the factory inspection results are significantly different from the last type inspection, f) When the national quality supervision agency proposes a type inspection requirement. 6.2.2 Type inspection shall be carried out according to the items specified in Table 17. 6.2.3 Samples for type inspection shall be randomly selected from products that have passed the factory inspection. 6.3 Sampling and determination rules
6.3.1 Sampling shall be carried out according to the single sampling plan in GB/T13264, and the qualified quality level AQL=1.26.3.2 After sampling inspection, determination shall be made according to the following provisions: a) For Class A items,a) If one item is unqualified, it will be judged as unqualified; b) For Class B items, if one item is unqualified, double sampling should be carried out for the item. If there is still one unqualified item, it will be judged as unqualified; c) For Class C items, it will be used as a reference item for inspection depending on the situation. 7 Marking and packaging
7.1 Each drill bit should be numbered and accompanied by a drill bit card and product inspection certificate. The drill bit type, number, inspection date and the seal of the inspector should be indicated on the certificate.
7.2 The drill bit product packaging should adopt inner and outer packaging. Before inner packaging, the drill bit body should be sandblasted and oiled, and then wrapped in plastic packaging bags or wax paper and fixed in a foam plastic box. The packaging should be in wooden boxes. The outer wall of the wooden box should be marked with the manufacturer's name and address, product name and quantity. 87
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