- Masterpiece in the world 2021/02/10 UP
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Masterpiece in the world #34
Gripping accuracy of 0.01 mm T.I.R. or less!
No jaw reshaping required – Kitagawa’s next-generation standard chuck “BR series” and T nut “Tnut-Plus”
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- Peripherals
When a standard chuck is used to clamp a workpiece, the jaws can be lifted. As attaching and detaching soft jaws decreases gripping accuracy, the jaws require reshaping after re-attached.Kitagawa’s next-generation standard chuck “BR series” and an optional T nut “Tnut – Plus” give a solution to such a problem and contribute to a drastic increase in gripping accuracy.
Background of development of highly accurate, large-diameter through hole hollow power chuck “BR series”
Taking on challenge to drastically improve basic performance of standard chuck
Kitagawa’s existing standard chuck “B-208” was developed 34 years ago in 1986, and the BB208” with a large through hole more than 20 years ago in 1997. Despite being an old design, the chucks are highly reviewed as the standard and still popular in the market. In addition to the products, the company began developing a new chuck based on the policy of providing customers with new value in the new era. In the development phase, they focused on controlling elastic deformation of master jaws and reducing the lifting. When a chuck clamps a workpiece, a several tons of load is imposed on the workpiece from the wedge plunger, and overturning moment caused by gripping reaction force from the workpiece is put on the master jaws. As a result, elastic deformation that causes lifting of the jaws occurs.
Widened master jaw wedge to ensure gripping accuracy of 0.01 mm T.I.R. or less
As chucks generally have a small number of parts and limited sizes of outer diameters and through holes, the key to the solution was how they devise ways to shape chuck parts and ramp up the performance. They focus on the master jaw wedge and widened it so that the wedge can support the dovetail area.This led to higher chuck rigidity, reducing the lifting of the master jaws. With increased rigidity, the chuck became less likely to deform. Besides, the improved balance of the load from the master jaws to the wedge plunger has resulted in greater gripping accuracy. Although the gripping accuracy of the existing models is approximately 0.02 mm T.I.R., the BR series successfully achieved 0.01 mm or less. Higher gripping accuracy drastically increased process performance and contributed to lowering the number of processes and failure rates and boosting product quality. The BR series supports machining of workpieces that require high accuracy.
Customer voice:
- “I felt that the gripping accuracy was even better than 0.01 mm T.I.R.”
- “For O.D. turning of round bars, we used to do “turn-bar” machining in which workpieces are inverted to be cut. As setup changes were needed between process 1 and process 2, we had to measure and adjust the runout every time. With the BR Series, such processes are not necessary. Besides the joint area of holes has become almost seamless.”
T-nut “Tnut – Plus” for BR series
Achieving “Zero Gap” between Master Jaw and Soft Jaw Groove
Reshaping of soft jaws, which is necessary at the time of chuck setup change, may be one of the usual processes at the shop floor. The BR series “Tnut-Plus” is a product that breaks the mold and saves the time and effort for reshaping as much as possible.Products that eliminate jaw reshaping have already been available in the market, but “Tnut-Plus” is the standard BR chuck that can use the standard soft jaws.
No more reshaping at the time of setup change
Gripping accuracy is lowered when soft jaws are attached or detached. This is because gaps are generated between the master jaw groove and the T nut, and the soft jaw and the T nut, which can result in misalignment of jaw mounting positions.To tackle the problem, we made the key width of “Tnut-Plus” a little wider than the master jaw and soft jaw groove widths. What’s more, we made a relief cut on the side surface of the key, and the master jaw contact surface and the soft jaw contact surface are misaligned in the direction of the groove, respectively.The key of T nut is tilted to insert into the master jaw. When a bolt is tightened, serrations are engaged and the soft jaw and master jaw are forcefully and properly faced each other. The key larger than the groove is fit in and tightly fixed. This way the gap of the both grooves are eliminated, and positioning repeatability of the soft jaws can be ensured.
Because there is no need to reshape soft jaws any longer, shop owners can eliminate the time-consuming task and maintain stable product quality at their production sites with a fewer number of veteran engineers.The product is available at low prices, so it is possible to recoup the initial cost at an early stage.
Customer voice:
- We have not reshaped soft jaws for more than six months, but they keep the same gripping accuracy even after reattachment.
- Wear of soft jaws has drastically reduced.
Wide use at every shop floor
“BR series” + “Tnut-Plus”
The BR series is mostly used by the customers who engage in high-mix and low to medium volume production in the automotive and industrial machinery sectors. The Tnut-Plus, on the other hand, is mainly used by those who manufactures a small lot of products and whose needs many setup changes in the course of machining processes. The Tnut-Plus is a product for the BR series that ensures high dimensional control. Although it is an option, we recommend that they be used together.
The BR series and Tnut-Plus can be used in a wide range of sectors. They make it possible for shop owners to achieve machining at a higher level.
| Kitagawa Corporation 77-1 Motomachi, Fuchu City Hiroshima, Japan 726-8610 URL：https://www.kitagawa.com/ |
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