JB/T 7968.2-1999 This standard is a revision of JB/T 7968.2-95 "Technical conditions for gear hobs before grinding". During the revision, only editorial changes were made according to relevant regulations, and the technical content remained unchanged. This standard is part of the JB/T 7968 "Gear hobs before grinding" series of standards, which includes two parts: JB/T 7968.1: Basic types and dimensions JB/T 7968.2: Technical conditions This standard specifies the technical requirements and basic requirements for marking and packaging of integral gear hobs before grinding (hereinafter referred to as hobs). This standard stipulates that the accuracy of the hob meets the B grade in GB/T 6084-1985 "General Technical Conditions for Gear Hobs". This standard applies to hobs produced according to JB/T 7968.1. This standard was first issued as GB 8062.2-87 on January 1, 1996 and was adjusted to JB/T 7968.2-95 in April 1996. JB/T 7968.2-1999 Gear hobs before grinding Part 2: Technical conditions JB/T7968.2-1999 Standard download decompression password: www.bzxz.net

ICS25.100
Machinery Industry Standard of the People's Republic of China
JB/T7968.2-1999
Gear Hobs Before Grinding
Part 2: Technical Conditions
Issued on 1999-05-20
State Bureau of Machinery Industry
Implementation on 2000-01-01
JB/T7968.2-1999
This standard is a revision of JB/T7968.2-95 (formerly GB8062.2-87) "Technical Conditions for Gear Hobs Before Grinding". The chapter on performance test was deleted during the revision, and editorial modifications were made in accordance with relevant regulations. Other technical contents remain unchanged. This standard is part of the JB/T7968 series of standards for pre-grinding gear hobs, which includes the following two parts: JB/T7968.1—1999
JB/T7968.2—1999
Pre-grinding gear hobs
Pre-grinding gear hobs
Part 1: Basic types and dimensions
Part 2: Technical conditions
This standard replaces JB/T7968.2—95 from the date of implementation. This standard is proposed and managed by the National Technical Committee for Tool Standardization. The responsible drafting units of this standard are Harbin No. 1 Tool Factory and Chengdu Tool Research Institute. The main drafters of this standard are Jiang Gongwei, Zhang Chao and Shen Shichang.
Standard of the Machinery Industry of the People's Republic of China
Gear Hobs Before Grinding
Part 2: Technical Conditions
JB/T7968.2-1999
Replaces JB/T79682-95
This standard specifies the technical requirements and basic requirements for marking and packaging of gear hobs before grinding (hereinafter referred to as hobs). The accuracy of the hobs specified in this standard conforms to Class B in GB/T6084-1985 "General Technical Conditions for Gear Hobs".
The provisions contained in the following standards constitute the provisions of this standard by reference in this standard. When this standard is published, the versions shown are 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/T1957—1981
GB/T 60841985
JB/T7968.1—1999
YB(T)2—1980
Technical requirements
Smooth limit gauge
General technical conditions for gear hobs
Gear hobs before grinding
Basic types and dimensions
Part 1:
Technical conditions for high-speed tool steel
The hob is made of W6Mo5Cr4V2 or other high-speed steel with equivalent performance, and its metallographic structure shall comply with the provisions of YB(T)2: its carbide uniformity shall not exceed grade 4 for hobs with a diameter not exceeding 100mm, and shall not exceed grade 5 for hobs with a diameter greater than 100mm.
The hardness of the cutting part of the hob is:
63-66HRC
The hob surface shall not have cracks, burns or other defects that affect the performance. The surface roughness of the hob shall be as specified in Table 1.
Inner hole surface
Pillow block outer circle
Front of the tooth
Side of the tooth
Top surface of the tooth and fillet
Surface roughness parameters
The outer diameter deviation of the hob is h15, the total length deviation is js15, and the other main tolerances shall be as specified in Table 2. Approved by the State Machinery Industry Bureau on May 20, 1999 um
2000-01-01
Inspection items and schematics
Aperture deviation
JB/T 7968.2-1999
1 The length of the bell mouth that exceeds the tolerance on the inner hole matching surface should be less than 25% of the matching length on each side. The width of the part that exceeds the tolerance on both sides of the keyway should not be greater than half of the key width on each side. 2When checking the accuracy of the hole, the reference spindle with the nominal hole diameter (according to (GBT1957 through end) should be able to pass through the hole. Radial runout of the shaft table
End face runout of the shaft table
Radial runout of the cutter teeth
The maximum difference in the distance from the tooth seat to the center of the inner hole within one rotation of the hob. Radiality of the front of the cutter teeth
The distance between two planes parallel to the theoretical front of the actual front of the cutter teeth within the measuring range 6D
Module (mm)
Inspection items and schematics
Difference in adjacent pitches of the chip groove
The maximum difference between two adjacent pitches on the same circumference near the hob dividing circle
Chip groove pitch Maximum cumulative error
JB/T7968.2-1999
Table 2 (continued)
On the same circumference near the hob dividing circle, the maximum deviation between the mutual positions of any two tooth front faces Parallelism of the tooth front face and the inner hole axis
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In the measurement range near the dividing circle, the distance between two planes parallel to the theoretical front face that accommodate the actual front face 12
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Inspection items and schematic
Tooth profile error
JB/T 7968.2—1999
Table 2 (Continued)
Within the measuring range of the inspection section, the normal distance between two theoretical straight tooth profiles that accommodate the actual tooth profileTooth thickness deviation
Deviation of the tooth thickness measured at the theoretical tooth height of the hob from the nominal tooth thickness
Maximum pitch deviation
On any row of teeth,
Maximum deviation
Axial pitch of adjacent teeth
Maximum cumulative error of the tooth pitch within any three pitch lengths SPx
>2~-35
Inspection items and illustration
Helix error of adjacent cutting edges||tt ||JB/T7968.2-1999
Table 2 (continued)
Maximum axial error of the intersection of adjacent cutting edges and the concentric cylindrical surface of the inner hole to the theoretical helix of the hob. Error of the spiral line of the cutting edge within one revolution of the hob.
Maximum axial error of the intersection of the cutting edge and the concentric cylindrical surface of the inner hole to the theoretical helix within one revolution of the hob. Error of the spiral line of the cutting edge within three revolutions of the hob.
Deviation of the thickness of the cam
Module (mm)
Inspection items and illustration
Deviation of the total height of the cam
JB/T 7968.2—1999
Table 2 (end)
he> 1-2..
.± 150
± 250
..± 300
5The precision of the finished product of the hob shall be checked by the first inspection method. When the conditions of the production plant are not met, the second inspection method may be used. 3.6
The first group: AZ, △Z, △Z, AfAf, , Af, AF, Adr, Adx, ADAde, AS, △HAhe
The second group: Ap, Ap3, AAAf, A, △F, △dir, △dx, △AD, △da, △S, △H, △heo3.7The polished length of the hob tooth side shall not be less than half of the tooth length when m≤4; and not less than one third of the tooth length when m>4. 4 Marking and packaging
4.1.1 The end surface of the hob should be marked with:
Manufacturer's trademark, module, reference tooth angle, helix angle on the hob cylinder, helix direction (right-handed not marked), material (ordinary high-speed steel not marked), manufacturing year, and pre-grinding code. 4.1.2 The packaging box should be marked with:
Manufacturer's name, address and trademark, product name, module, reference tooth angle, material, manufacturing year, and standard code. 2 Packaging
The hob should be rust-proofed before packaging, and the packaging should be firm to prevent damage during transportation. 6
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