Design chucks

ピン拡張式 マルチジョウチャック SOUL-Woodworthシリーズ

For chucking thin-walled cylindrical work-pieces with uneven surface!

The thin-walled cylindrical work-pieces are subject to elastic deformation even under small force such as clamping force, cutting resistance or centrifugal force. Therefore this kind of work-pieces require several counter measure such as to secure the roundness accuracy or prepare the special chucks and cutting tools for anti-vibration, and add some extra operation.
The MUL chuck has the floating mechanism which enables to clamp the surface of the thin-walled cylindrical work-pieces with equal force and it is effective to the uneven material work-pieces. Furthermore, the Multi-Jaws function allows to have soft and strong clamping torque without deform the work-pieces and also add more rigidity on processed portion. Then it is possible to obtain the roundness accuracy in the first operation even when processing deformable cast & wrought, or press formed thin walled cylindrical work-pieces.


  • 外径把握用
  • 内径把握用
  • 大型サイズ
  • カートリッジ式
  • UBL&MULコンビ

MUL Multi Jaw Chuck

Suitable for thin-walled work-piece processing!

Thin-walled work-piece is difficult work-piece!

Thin-walled cylindrical work-pieces are easily deformed or deflected even by a small gripping, cutting, or centrifugal force, so they require difficult cutting conditions and many finishing processes.

The Multi Jaw design minimizes distortion!

The holding force [Clamping torque] of the work-pieces or the clamping torque is a total of the force on each jaw multiplied by friction factor. Since the Multi Jaw type is adopted many clamping points and spiked jaw tips, a small force on each point can provide a strong clamping torque.
Both the pushing force and the distance between of the jaws at each clamping portion of the MUL [24 points clamping] are only a quarter of the UBL's [6 points clamping].

Even distribution of clamping force by a floating mechanism!

Once all the jaw pins, which are designed to accommodate uneven surfaces, are in contact with the work-piece, evenly distributed forces are applied.
* The MUL chuck has high-performance compensating function therefore there would be no problem if work-piece has center difference between datum of concentricity and clamping portion.


  1. High level roundness of machining for Thin-walled workpieces.
  2. Grips uneven surface workpieces uniformly with the floating mechanism.
  3. Powerful clamping torque with a soft touch.
  4. The Multi-jaw design minimizes distortion.
  5. Greatly increases the workpiece rigidity.
  6. Offers a High/Low clamping application depending on machining conditions.
  7. Allows a broad range of design responding to various gripping diameters.
  8. Flexibly responds to various design requirements.


For O.D. Clamping

For I.D. Clamping


Variety of Multi-jaw Chucks Design

Correspond flexibly for large-size workpieces, quick change and etc.

Solution for the processing problem of I.D. surface of brake drum for Big cars

The chucks in the right picture is delivered to Okuma for vertical lathe machines as finishing operation chuck of brake drums which require high roundness (total 7 units including spare chuck).
Okuma & Howa tried a test cut by face clamp system first but it did not work to obtain 0.1mm roundness and caused vibration.
Our chuck makes it possible to process in good condition within 0.01mm (1/10 of above) roundness with no vibration.

It is able to correspond to 6 kinds of brake drums by 3 kinds of cartridge systems.

Multi Jaw Chuck is able to clamp wide range (Jaw pin stroke 20mm). Furthermore, the cartridge type MUL chuck are available for various work-pieces that have more than 30mm differences in diameter.
Also, other MUL chuck with build in centering mechanism design is available.
The MUL chuck in right picture was designed for 6 kinds of brake drums.

☆Cartridge / Centering mechanisms have been patented in domestic and overseas.


UBL & Multi Jaw Combination Chuck

Gear Pitch Line Basis Diaphragm Chuck

N.A.Woodworth社【米国】が開発したUBL(鋳・鍛造ワーク最強デザイン)とSOUL(日本) が開発したMULマルチジョウ(薄肉対応デザイン)を組み合わせた薄肉ワーク一発仕上げの最強コンビ

For Finishing Brake Drum (Thin-Walled Workpieces) In One Chucking.

The UBL and MUL combination design has been developed to meet the demand for more efficient cutting of brake drums for pick-up trucks with a vertical lathe. This combination chuck enables a vertical lathe to efficiently perform both heavy-duty rough cutting and finishing of the shoe surface that requires high levels of roundness.


  1. Provides powerful chucking.
  2. Offers the highest level of roundness in OD clamping
  3. Allows one machine to complete the total turning operation.
  4. Incorporates user-friendly design.
  5. Ensures operational safety by MUL guide.
  6. Eliminates the effect of chattering.
  7. Responds to various kinds of workpieces with the long-stroke MUL.


The Total Design Concept Flexibly Meets Various Needs.

The UBL & MUL combination chuck is not only ideally suited for brake drums but also for the streamlining of production of other various thin-walled workpieces. Also, the total design concept of MUL allows the combination chuck to flexibly meet various requirements according to the shape and number of thin-walled workpieces, machining conditions, and required accuracy.