1 Introduction
High-speed machining has become an important part and development direction of modern machinery manufacturing technology. At present, industrial developed countries have begun to widely use high-speed cutting machine tools with spindle speeds of tens of thousands of revolutions per minute or even tens of thousands of revolutions. China's automobile, tractor, aerospace and other industries have introduced a large number of advanced production lines, machining centers and high-performance machine tools from abroad, including many high-speed cutting machine tools. In the case of a large increase in the operating speed of the machine tool spindle, the machining performance of the conventional BT (7:24 taper) tool system has been difficult to meet the requirements of high-speed cutting. To this end, industrialized countries are competing to develop a variety of new tool systems that can meet the needs of high-speed cutting. Currently, the HSK (German Hohl Schaft Kegel abbreviation) tool system in Germany, the KM tool system in the United States, and the NC5 in Japan are widely used. The Big-Plus tool system, etc., in which the HSK system technology is the most mature, the application range is also the most extensive. The HSK tool system adopts a hollow short cone structure and a two-sided clamping method, and has superior performance in terms of system stiffness, radial round runout accuracy, repeated mounting accuracy, and clamping reliability. The manufacturing accuracy of the tool system directly affects its performance. This paper analyzes the main differences between the German DIN standard and the ISO standard of the HSK tool system, discusses the impact on the positioning accuracy and joint stiffness of the HSK tool system, and provides reference and reference for the development of the new domestic tool system.
2 Development of HSK tool system standards
Since 1987, a special working group has been set up by more than 30 units including the machine tool laboratory (WZL) of Achen University of Technology and some tool manufacturers, machine tool manufacturers and user companies. Under the leadership of Professor M.Weck, a new type of work has begun. Research and development work on tool systems. After the first round of research, the working group submitted the “Automatic Tool Changer Hollow Handle†standard recommendation to the German Industrial Standards Organization in July 1990. In July 1991, Germany published the draft DIN standard for the HSK tool system and recommended to the International Organization for Standardization the development of relevant ISO standards. In May 1992, the International Organization for Standardization ISOT/TC29 (Tools Technical Committee) decided not to formulate the ISO standard for automatic tool changeable hollow handles. After the second round of research by the Working Group, Germany established the official industrial standard DIN 69893 for the HSK tool system in 1993. In May 1996, at the ISO/TC29/WG33 review meeting, the HSK tool system based on DIN 69893 was developed. Draft ISO standard ISO/DIS12164. After many revisions, the official ISO standard ISO12164 for HSK tool systems was issued in 2001.
3 Main differences between DIN and ISO standards
Prior to the promulgation of the official ISO standard for HSK tool systems, the HSK tool system related products produced by various countries were designed and manufactured according to the German standards DIN69893 and DIN69063 (specifying the shape and size of the spindle mounting holes). However, the official ISO standard ISO12164 of the HSK tool system has made several important improvements to the DIN standard. These differences will have a greater impact on the performance of the HSK tool system.
In the HSK tool system, the quality of the fit between the taper of the shank and the taper hole of the machine tool directly affects its performance and accuracy. Therefore, it is the key to the HSK tool system standard that the manufacturing accuracy of the shank taper and the spindle hole of the machine tool should be properly determined. problem. In this regard, the DIN standard and the ISO standard use two distinct treatment methods. Taking the HSK-A type shank as an example, the main control dimensions of the shank taper and the spindle taper specified in the DIN standard are shown in Fig. 1. Table 1 shows the relevant dimensions of the HSK-A63 shank taper and the spindle taper.
It can be seen from Fig. 1 that in the DIN standard, the HSK shank taper consists of two sections of diameter dimensions d2 (large end), d3 (small end) and two sections of position dimensions l2, l3 and taper (1:10). To control. The corresponding spindle taper hole is controlled by the large end diameter D2, the position dimension L2 of the section, and the taper angle corresponding to the taper (1:10). In the DIN standard, the spindle taper holes are not specified for L3 and D3 dimensions. For ease of analysis, "*L3" and "*D3" are used to indicate the spindle taper hole size corresponding to the taper taper sizes l3 and d3. The tolerance band of the HSK-A shank taper and the spindle taper specified in the DIN standard is shown in Figure 2.
The limit size at the small end of the HSK-A63 spindle taper hole corresponding to the DIN standard is
When the taper of the shank is matched with the taper hole of the spindle, the maximum and minimum interference at the big end d2 and the small end d3 are respectively
When the taper of the shank is matched with the taper hole of the spindle, the maximum and minimum interference at the big end d2 and the small end *d3 are respectively
4 Performance analysis using two standard HSK tool systems
The positioning accuracy and joint stiffness of the tool holder are two important indicators for measuring the performance of the tool system. The following is a comparative analysis of the positioning accuracy and joint stiffness of HSK shanks using DIN and ISO standards.
Positioning accuracy
The positioning accuracy of the HSK tool holder includes axial positioning accuracy and radial positioning accuracy. Since HSK shanks using both DIN and ISO standards are axially positioned using end faces, both have high axial positioning accuracy (<0.001 mm) and there is no difference. Since the HSK shank uses the tapered surface to achieve radial centering, its radial positioning accuracy is determined by the fit of the large end of the HSK shank cone and the large end of the spindle taper. Take HSK-A63 type shank and main shaft as an example. When manufacturing according to DIN standard, the average interference at the big end is 8Micro; m, when manufactured according to ISO standard, the average interference at the big end is 12Micro; m. Therefore, the use of the ISO standard is more conducive to the positioning accuracy of the tool holder.
2. Connection stiffness
The coupling stiffness between the HSK tool holder and the main shaft is closely related to the fit of the HSK shank taper surface to the spindle taper hole and the tightening of the shank, the shank end face and the spindle end face.
The deformation curve of the HSK tool holder under the cutting load is shown in Fig. 5. As can be seen from the figure, there are two states of the joint stiffness of the HSK shank. The working load of the A-segment curve is lower, the joint stiffness of the shank is higher (less deformation), and the joint stiffness at this time is related to the structural size of the front end of the shank; the B-segment curve indicates that the working load used as the shank is increased to After a certain degree, the deformation of the shank increases sharply, the joint stiffness decreases, the dynamic stiffness is low, and the work performance deteriorates. This feature is related to the size of the shank taper and the cooperation of the shank and the spindle taper.
Take the HSK-A63 tool holder and the spindle taper hole as an example. When manufacturing according to DIN standard, the maximum interference at the big end is 12μm, the minimum interference is 4μm; the maximum interference at the small end is 8μm, the minimum The interference is -1 μm (that is, a gap occurs). When manufactured according to the ISO standard, the maximum interference at the big end is 17 μm, the minimum interference is 7 μm; the maximum interference at the small end is 14 μm, and the minimum interference is 4 μm. Comparing the interference between the two standard tool holders, the interference between the HSK tool holder and the spindle taper hole manufactured according to the DIN standard is small, which is beneficial to ensure that a sufficiently large clamping force is transmitted to the end surface of the tool holder. It fits snugly to the end face of the spindle to achieve high joint stiffness over a large working load range, but the joint stiffness will drop sharply under heavy load conditions, deteriorating working conditions. The tolerance of the shank manufactured according to the ISO standard and the taper hole of the spindle is large, so that the working load range which can maintain a high joint rigidity is reduced. The ISO standard states that as long as the clamping force is not less than the value specified in the standard, it is ensured that more than 70% of the clamping force is transmitted to the end face of the shank, so the reduction of the working load range is limited. The taper of the shank specified by the ISO standard (1:9.98) is not consistent with the taper of the spindle taper hole (1:10), so that the large end of the cone is first contacted during the tightening of the taper of the shank and the taper of the spindle. With the elastic deformation, the shank and the end face and the tapered surface of the main shaft are in full contact with each other to ensure the axial and radial mounting positioning accuracy, and it is advantageous to prevent the working load range with high coupling rigidity from being reduced. If the shank taper is set to 1:9.94, the small end interference is still comparable to the DIN standard. It can be seen that the shank and the spindle taper manufactured according to the ISO standard have high joint rigidity and good cutting performance under heavy load conditions. In addition, the amount of interference between the HSK tool holder and the spindle taper hole manufactured according to the ISO standard is small, so the system performance is more stable.
5 Conclusion
The HSK tool system manufactured according to the ISO standard has a large interference between the shank and the spindle taper hole, which makes it easier to ensure the positioning accuracy of the HSK tool holder and the stability of the system performance.
The ISO standard is reasonable for different taper tapers (1:9.98 and 1:10) for the taper taper and the spindle taper, which is beneficial to better performance advantages of the HSK tool system.
The HSK tool system manufactured to ISO standards is more conducive to heavy-duty cutting while ensuring sufficient clamping force.
The shank of the HSK tool system manufactured according to DIN standard has a slightly smaller interference with the spindle taper hole, and the clamping is more reliable, which is more suitable for high speed and light load machining.
We offer prototyping service, also high volume production capability. Whatever you need a very small batch for R&D, or cost down project with high volume. It will be warmly welcome.
High-speed machining has become an important part and development direction of modern machinery manufacturing technology. At present, industrial developed countries have begun to widely use high-speed cutting machine tools with spindle speeds of tens of thousands of revolutions per minute or even tens of thousands of revolutions. China's automobile, tractor, aerospace and other industries have introduced a large number of advanced production lines, machining centers and high-performance machine tools from abroad, including many high-speed cutting machine tools. In the case of a large increase in the operating speed of the machine tool spindle, the machining performance of the conventional BT (7:24 taper) tool system has been difficult to meet the requirements of high-speed cutting. To this end, industrialized countries are competing to develop a variety of new tool systems that can meet the needs of high-speed cutting. Currently, the HSK (German Hohl Schaft Kegel abbreviation) tool system in Germany, the KM tool system in the United States, and the NC5 in Japan are widely used. The Big-Plus tool system, etc., in which the HSK system technology is the most mature, the application range is also the most extensive. The HSK tool system adopts a hollow short cone structure and a two-sided clamping method, and has superior performance in terms of system stiffness, radial round runout accuracy, repeated mounting accuracy, and clamping reliability. The manufacturing accuracy of the tool system directly affects its performance. This paper analyzes the main differences between the German DIN standard and the ISO standard of the HSK tool system, discusses the impact on the positioning accuracy and joint stiffness of the HSK tool system, and provides reference and reference for the development of the new domestic tool system.
2 Development of HSK tool system standards
Since 1987, a special working group has been set up by more than 30 units including the machine tool laboratory (WZL) of Achen University of Technology and some tool manufacturers, machine tool manufacturers and user companies. Under the leadership of Professor M.Weck, a new type of work has begun. Research and development work on tool systems. After the first round of research, the working group submitted the “Automatic Tool Changer Hollow Handle†standard recommendation to the German Industrial Standards Organization in July 1990. In July 1991, Germany published the draft DIN standard for the HSK tool system and recommended to the International Organization for Standardization the development of relevant ISO standards. In May 1992, the International Organization for Standardization ISOT/TC29 (Tools Technical Committee) decided not to formulate the ISO standard for automatic tool changeable hollow handles. After the second round of research by the Working Group, Germany established the official industrial standard DIN 69893 for the HSK tool system in 1993. In May 1996, at the ISO/TC29/WG33 review meeting, the HSK tool system based on DIN 69893 was developed. Draft ISO standard ISO/DIS12164. After many revisions, the official ISO standard ISO12164 for HSK tool systems was issued in 2001.
3 Main differences between DIN and ISO standards
Prior to the promulgation of the official ISO standard for HSK tool systems, the HSK tool system related products produced by various countries were designed and manufactured according to the German standards DIN69893 and DIN69063 (specifying the shape and size of the spindle mounting holes). However, the official ISO standard ISO12164 of the HSK tool system has made several important improvements to the DIN standard. These differences will have a greater impact on the performance of the HSK tool system.
In the HSK tool system, the quality of the fit between the taper of the shank and the taper hole of the machine tool directly affects its performance and accuracy. Therefore, it is the key to the HSK tool system standard that the manufacturing accuracy of the shank taper and the spindle hole of the machine tool should be properly determined. problem. In this regard, the DIN standard and the ISO standard use two distinct treatment methods. Taking the HSK-A type shank as an example, the main control dimensions of the shank taper and the spindle taper specified in the DIN standard are shown in Fig. 1. Table 1 shows the relevant dimensions of the HSK-A63 shank taper and the spindle taper.
(a) shank taper (b) spindle taper hole Figure 1 HSK-A shank taper and spindle taper hole main control size (DIN standard)
| D2 | D3 | L2 (L2) | D2 | L3 (L3) | AT3 | |||||||||
| Mm | " | |||||||||||||
|
| 6.3 |
| 14.7 | twenty one | |||||||||
It can be seen from Fig. 1 that in the DIN standard, the HSK shank taper consists of two sections of diameter dimensions d2 (large end), d3 (small end) and two sections of position dimensions l2, l3 and taper (1:10). To control. The corresponding spindle taper hole is controlled by the large end diameter D2, the position dimension L2 of the section, and the taper angle corresponding to the taper (1:10). In the DIN standard, the spindle taper holes are not specified for L3 and D3 dimensions. For ease of analysis, "*L3" and "*D3" are used to indicate the spindle taper hole size corresponding to the taper taper sizes l3 and d3. The tolerance band of the HSK-A shank taper and the spindle taper specified in the DIN standard is shown in Figure 2.
The limit size at the small end of the HSK-A63 spindle taper hole corresponding to the DIN standard is
*D3max=D2max-2*L3 tg(2°51'45"-AT3/2)=46.534mm
*D3min=D2min-2*L3 tg(2°51'45")=46.529mm
When the taper of the shank is matched with the taper hole of the spindle, the maximum and minimum interference at the big end d2 and the small end d3 are respectively
D2max=d2max-D2min=12μm
D2min=d2min-D2max=4μm
D3max=d3max-D3min=8μm
D3min=d3min-D3max=-1μm (gap)
(a) shank taper tolerance band (b) spindle taper hole tolerance band Figure 2 HSK-A shank taper and spindle taper hole tolerance band (DIN standard)
(a) shank taper (b) spindle taper hole Figure 3 Main control dimensions of HSK-A shank taper and spindle mounting hole (ISO standard)
| D2 | t | L2 (L2) | D2 | T |
| Mm | ||||
| 48.010 | 0.003 | 6.3 | 47.998 | 0.002 |
(a) shank taper tolerance zone (b) spindle taper tolerance zone Figure 4 HSK-A shank taper and spindle taper tolerance zone (ISO standard)
D2max=d2+t=48.0 13mm
D2min=d2-t=48.007mm
*d3max=d2-*l3/ 9.98+t=46.540mm
*d3min=d2 -*l3/9.98-t=46.534mm
D2max=D2+T=48.000mm
D2min=D2-T=47.996mm
*D3max=D2-*L3/10+T=46.530mm
*D3min = D2-*L3/10-T=46.526mm
When the taper of the shank is matched with the taper hole of the spindle, the maximum and minimum interference at the big end d2 and the small end *d3 are respectively
D2max=d2max-D2min=17μm
D2min=d2min-D2max=7μm
D3max=*d3max-*D3min=14μm
D3min=*d3min-*D3max=4μm
4 Performance analysis using two standard HSK tool systems
The positioning accuracy and joint stiffness of the tool holder are two important indicators for measuring the performance of the tool system. The following is a comparative analysis of the positioning accuracy and joint stiffness of HSK shanks using DIN and ISO standards.
Positioning accuracy
The positioning accuracy of the HSK tool holder includes axial positioning accuracy and radial positioning accuracy. Since HSK shanks using both DIN and ISO standards are axially positioned using end faces, both have high axial positioning accuracy (<0.001 mm) and there is no difference. Since the HSK shank uses the tapered surface to achieve radial centering, its radial positioning accuracy is determined by the fit of the large end of the HSK shank cone and the large end of the spindle taper. Take HSK-A63 type shank and main shaft as an example. When manufacturing according to DIN standard, the average interference at the big end is 8Micro; m, when manufactured according to ISO standard, the average interference at the big end is 12Micro; m. Therefore, the use of the ISO standard is more conducive to the positioning accuracy of the tool holder.
2. Connection stiffness
The coupling stiffness between the HSK tool holder and the main shaft is closely related to the fit of the HSK shank taper surface to the spindle taper hole and the tightening of the shank, the shank end face and the spindle end face.
The deformation curve of the HSK tool holder under the cutting load is shown in Fig. 5. As can be seen from the figure, there are two states of the joint stiffness of the HSK shank. The working load of the A-segment curve is lower, the joint stiffness of the shank is higher (less deformation), and the joint stiffness at this time is related to the structural size of the front end of the shank; the B-segment curve indicates that the working load used as the shank is increased to After a certain degree, the deformation of the shank increases sharply, the joint stiffness decreases, the dynamic stiffness is low, and the work performance deteriorates. This feature is related to the size of the shank taper and the cooperation of the shank and the spindle taper.
Figure 5 Deformation curve of DIN holder under static load
Take the HSK-A63 tool holder and the spindle taper hole as an example. When manufacturing according to DIN standard, the maximum interference at the big end is 12μm, the minimum interference is 4μm; the maximum interference at the small end is 8μm, the minimum The interference is -1 μm (that is, a gap occurs). When manufactured according to the ISO standard, the maximum interference at the big end is 17 μm, the minimum interference is 7 μm; the maximum interference at the small end is 14 μm, and the minimum interference is 4 μm. Comparing the interference between the two standard tool holders, the interference between the HSK tool holder and the spindle taper hole manufactured according to the DIN standard is small, which is beneficial to ensure that a sufficiently large clamping force is transmitted to the end surface of the tool holder. It fits snugly to the end face of the spindle to achieve high joint stiffness over a large working load range, but the joint stiffness will drop sharply under heavy load conditions, deteriorating working conditions. The tolerance of the shank manufactured according to the ISO standard and the taper hole of the spindle is large, so that the working load range which can maintain a high joint rigidity is reduced. The ISO standard states that as long as the clamping force is not less than the value specified in the standard, it is ensured that more than 70% of the clamping force is transmitted to the end face of the shank, so the reduction of the working load range is limited. The taper of the shank specified by the ISO standard (1:9.98) is not consistent with the taper of the spindle taper hole (1:10), so that the large end of the cone is first contacted during the tightening of the taper of the shank and the taper of the spindle. With the elastic deformation, the shank and the end face and the tapered surface of the main shaft are in full contact with each other to ensure the axial and radial mounting positioning accuracy, and it is advantageous to prevent the working load range with high coupling rigidity from being reduced. If the shank taper is set to 1:9.94, the small end interference is still comparable to the DIN standard. It can be seen that the shank and the spindle taper manufactured according to the ISO standard have high joint rigidity and good cutting performance under heavy load conditions. In addition, the amount of interference between the HSK tool holder and the spindle taper hole manufactured according to the ISO standard is small, so the system performance is more stable.
5 Conclusion
The HSK tool system manufactured according to the ISO standard has a large interference between the shank and the spindle taper hole, which makes it easier to ensure the positioning accuracy of the HSK tool holder and the stability of the system performance.
The ISO standard is reasonable for different taper tapers (1:9.98 and 1:10) for the taper taper and the spindle taper, which is beneficial to better performance advantages of the HSK tool system.
The HSK tool system manufactured to ISO standards is more conducive to heavy-duty cutting while ensuring sufficient clamping force.
The shank of the HSK tool system manufactured according to DIN standard has a slightly smaller interference with the spindle taper hole, and the clamping is more reliable, which is more suitable for high speed and light load machining.
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Label: Cone Hole System Stiffness Tool Holder Tool System Interference
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