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| CALL PROHOLD TOLL FREE AT: 1-888-565-7764 |
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HYDRAULIC EXPANDING PULLBACK
400mm HMC FIXTURE FOR LARGE
TILT-STEERING COLUMN U-JOINTS
(PATENTED)
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Large Tilt-Steering U-Joint
Pulldown Clamps On Top Three Buttons
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Large and Small [On Right] Tilt-Steering U-Joints
Pulldown Clamps On ID Shoulder [See Below]
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| PROHOLD's unique hydraulic expanding pullback clamping module can be used on parts with a minimum ID of 1.250" up to any larger diameter necessary. The modules can be arranged on the tombstones in a vertical, horizontal or any angular orientation desired. The number of pods that can be installed on a tombstone is limited by the size of the machine's machining envelope that can be used.
The tombstones below were manufactured to fit a Mazak 400mm pallet machining center. They have their own internal 24-volt DC powered closed-loop, internal hydraulic pumping unit. The operator has to manually make the connection between the 24-volt external DC power supply cord to the top plug of the tombstone at the load/unload station. After the power connection is made, the operator turns the manual valve to unclamp the parts. All stations simultaneously operate in sequence until they have released or unclamped all the parts. The operator then removes all the finished parts from each station.
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Top View of Tombstone
with Four Pullback Pods
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Top View of Tombstone
with Four Pullback Pods
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| After the finished parts have been removed from each station, the operator installs unfinished parts on each station, taking care to make sure the part extension arm used to locate the part radially is orientated between the spring-return part locator and the adjustable locator stop. Once all the parts have been loaded, the operator turns the manual valve to the clamp position and the sequenced locators on each pullback pod rotate the part into its correct radial position against the adjustable locator stop, then the pullback module fingers and ID expansion collet clamp the part.
The pullback clamping fingers are pulled down by the top swivel cap which can accommodate up to a 1/32" uneven clamping surface. This allows for an even clamping force around the whole diameter of the part. The ID expansion collet also provides centricity and clamping of the part on the ID. These parts do not move once clamped into position, allowing for heavy metal removal rates.
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Close-Up of Clamping Station Pod
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Part in Place Ready to Clamp
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| The pullback clamping fingers can be orientated in any radial position necessary for the particular part being processed. This part had three bosses that were not equally spaced about the diameter. The fingers were arranged to hit these bosses for a consistent clamping position on each part. The combination of the ID expansion collet, pullback clamping fingers and radial locator makes a perfect setup that presents the part with exposure that allows for very aggressive machining and accuracies that are consistent from part to part, not to mention the ease of operator use involved to do the job. |
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Top View of Clamping Station Pod
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Part Clamped Ready to Machine
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| These patented PROHOLD® pullback clamping modules can be made without using the ID expansion collet. The fingers can be designed to self-center the part while pulling back to clamp the part into position. When the ID expansion collet is not used, the height of the pullback module is much shorter in height. These pullback modules could be placed in the center of any 2-jaw or 3-jaw low-profile or standard hydraulic tombstone chucking station, similar to the 3-jaw, 4-chuck hydraulic tombstone example on the page 31 - Standard Hydraulic Tombstones. |
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HYDRAULIC EXPANDING PULLBACK
400mm HMC FIXTURE FOR SMALL
TILT-STEERING COLUMN U-JOINTS
(PATENTED)
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Front View Small Tilt-Steering U-Joint
[Machined Part On Right]
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Side View Small Tilt-Steering U-Joint
[Machined Part On Right]
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Top View Of Shoulder Inside ID Of U-Joint
[Machined Part On Right]
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Other Side View Small Tilt-Steering U-Joint
[Machined Part On Right]
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| For those hard-to-hold parts that require lots of machining about the part, the PROHOLD® [Patented] pullback module is the ultimate workholding fixture for these kinds of parts. Not only does it make life very easy for the operator, but it presents the part in a completely exposed position where you can hit it with any tool as hard as your machine can handle the job. All that is necessary to operate is to make the external 24-volt DC power connection to the top power plug, and then operate the manual valve to actuate all eight pullback pods.
This part is held down by its internal ID shoulder. The fingers on the pullback clamping mechanism in their retracted or unclamped position allow for the part to slip over the clamping fingers. As you can see in the photos immediately below, the fingers hug the pulldown shaft when retracted making for a small OD profile which is smaller than the ID of the part inside shoulder. When the pulldown clamp is actuated, you can see in the picture to the right immediately below that the fingers expand from their retracted position to an OD that is greater than the shoulder on the ID of the part. The bottom of each finger face engage the shoulder, and the top inside of the fingers is engaged by the swivel top cap of the pulldown shaft. The swivel cap allows for 1/32" accommodation of any uneven surface on the shoulder surface for even distribution of the clamping force down on the part.
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Pullback In Unclamped Position
Ready To Load Part
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Pullback In Clamped Position
Without Part Loaded
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Part Loaded In Unclamped Position
Ready To Clamp Part
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Part In Clamped Position
Ready To Machine
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| For presentation of the part for machining, there is no better system available on the market today. You can see from the two pictures below that the parts are completely hanging out there in the breeze, ready to be attacked from the right, left and center. The pullback top cap is designed with a low-profile to allow for machining of parts across the top without having to index and come at it from the other side when using older style clamping mechanisms, like hydraulic swing clamps [or "chip catchers"] that just get in the way of what you are doing, or want to do quicker. |
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Clearance Around Part
In Top Stations [Clamped]
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Clearance Around Part
In Bottom Stations [Clamped]
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Three Angle Pictures Of The Pullback Module Tombstone With Parts Clamped In Position
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Clearance Around Parts As
Presented By Pullback Module Pods
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Top View Of Pullback Module Tombstone
With Parts In Clamped Positions
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The pullback modules can be mounted on the tombstone in any orientation desired. These are the standard hydraulic tombstones that come with their own 24-volt DC internal hydraulic pumping units. These tombstones can be used with custom top-tooled faceplates, or for mounting pullback modules as shown. They are the most versatile, hyraulically actuated standardized tombstones available on the market today for 300mm machines on up in size, only available from PROHOLD® Workholding, Inc.
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Three Pictures Of The Pullback Module Tombstone With Parts Clamped In Horizontal Position
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| The pullback clamping modules with this horizontal presentation are the exact same modules used in the vertical presentation tombstone above. The pullback modules can be permanently orientated or mounted in any angle desired on the face of the tombstone, or can be rotated 360º on one degree increments. They can hold any parts with an ID opening of 1.25" or greater, up to and including truck wheels, etc. This is the best clamping method for parts with ID openings because it permits unrestricted access to the part by the cutting tools required to machine the part. Several tons of clamping force are applied through a uniform force distribution on the part using a swivel pulldown head that accommodates approximately 1/32" uneven surface where the fingers engage the part on pulldown. |
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Vertical Part Presentation Front
Horizontal Part Presentation Rear
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Part Clamped In Horizontal
Presentation Position
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Left Side View Of Part Clamped Horizontally
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Right Side View Of Part Clamped Horizontally
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Front View Of Part Clamped Horizontally
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| This first tombstone with vertically mounted pullback clamping modules is not necessary when the horizontal tombstone is fitted with indexible pullback modules. With this optional feature, each pullback module is indexible in 90 degree increments so that all four sides and the top of the part are presentable to the machine spindle. |
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HMC HYDRAULIC EXPANDING PULLBACK
FIXTURE FOR STEERING KNUCKLES
(PATENTED)
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BROCHURE HYDRAULIC PULL-BACK CLAMPING MODULE (Adobe® .pdf format)
VIDEO OF STEERING KNUCKLE PULLBACK MODULE:
WINDOWS®
REALVIDEO®
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Quarter for size at bottom
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Steering knuckle on Pullback
Module in unclamped position
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Steering knuckle on Pullback
Module in clamped position
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If you manufacture automobile or truck steering knuckles at your plant, you need the newest patented fixturing system from PROHOLD® to increase your overall productivity. PROHOLD's unique design reduced the number of machine tools needed to meet production requirements from seven two-pallet horizontal machining centers down to three two-pallet machines. PROHOLD's customer saved approximately $2 million in capital expenditures on machines and tooling by reducing the number of fixtures necessary to get the job done. PROHOLD® fixturing increased overall productivity of the manufacturing process and decreased the capital investment required to obtain these gains, providing a fixture designed to eliminate chip build-up, while simultaneously making the loading and unloading of parts much easier for the operator to manage.
This fixture utilizes a unique patented hydraulic expanding pullback module for clamping and securing steering knuckles, however, any kind of part designed with a through-hole in it could possibly be held with these modules. These hydraulic expanding pullback modules can be incorporated into any fixture to eliminate chip-catching standard modular tooling components. Using PROHOLD® pullback modules instead of modular tooling components provides more room on the fixture for more parts within the working envelope of the machine tool.
The fixture below was designed to accommodate four steering knuckles - two knuckles orientated on the side of the fixture for one geometric plane of machining operations, and two knuckles on the top of the fixture for the second geometric plane of machining. For every complete machining cycle of one pallet on the Makino A55 machine tool, two finished parts are produced off this fixture.
Take note of the fixture shape that was designed to eliminate chip buildup. The slanted profile of the fixture block allows chips to drop off the fixture. This is another big advantage inherent, as much as practically possible, in all PROHOLD® fixturing systems. PROHOLD® designs use only internally drilled hydraulic porting. Those tubes you see in the hydraulic rotary coupling housing in right-hand picture immediately below are used to connect the machine hydraulic system to the PROHOLD® fixture. You won't find a tube or tubing connection, internal or external, on any PROHOLD® fixture.
PROHOLD® designs its products to eliminate as many chip-catching components as possible, thereby further enhancing the ergonomic friendliness of its workholding systems. PROHOLD® also designs its fixturing systems to operate on lower hydraulic pressures, yet still provide high clamping forces. This prolongs the service life of the hydraulic components and seals.
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Side view of fixture
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Top angled view of fixture
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When mounted on the machine tool, hydraulic pressure is supplied to the fixture through the vertical manifold and controlled remotely by the operator. Hydraulic fluid is routed through a permanent connection to the rotary union on the manifold down through the internally drilled porting in the fixture block to the hydraulic expanding pullback modules. Dual hydraulic porting in the expanding pullback module mates up with the internal hydraulic porting of the fixture block when the module is installed.
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Steering knuckle in position on station
(work support not installed in this picture)
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Compare location with picture to the left
(work support not installed in this picture)
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The hydraulic expanding pullback modules used on this fixture block provide two methods of securing the steering knuckles. There is an expansion collet that engages the internal diameter of the knuckle and there are the pullback fingers that engage the top shoulder of the knuckle. PROHOLD® expanding pullback modules can be ordered without the expansion collet where the particular application does not require its use to satisfactorily clamp the part accurately and securely for machining. The fixture also has sequenced hydraulic work supports that automatically extend to support the link arms of the steering knuckle after initial clamping of the collet and pullback fingers.
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Locator side view of hydraulic support arm
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Other side view of hydraulic support arm
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The operator places the steering knuckle on the expanding pullback module. The knuckle slides over the expansion collet and seats on the position locators, adjustable locator and/or stop supports. The operator then applies hydraulic pressure to clamp the parts. Clamping expands the expansion collet to engage the internal diameter of the through-hole in the knuckle and extends the fingers to engage the top shoulder of the knuckle, pulling down the knuckle against the position locators and then the hydraulic support arms extend to engage the link arms on the steering knuckle. All four stations on the fixture are clamped simultaneously.
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| CALL PROHOLD TOLL FREE AT: 1-888-565-7764 |
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All features and designs of PROHOLD® products are subject to change without notice. Individual
features and designs incorporated into each individual fixture or chuck are dictated by the
requirements necessary for each part to be machined on the fixture or chuck and are
contractually set and agreed upon at the time an order is placed by the customer.
PROHOLD® Fixtures are patented in various countries
throughout Asia, North America and Europe.
PROHOLD® is a registered trademark in the European Union, Japan, Korea,
Taiwan, Malaysia, Canada, Mexico and the United States. Adobe® is a
registered trademark of Adobe Systems Incorporated.
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| Copyright© 1997-2003 PROHOLD® Workholding, Inc. All rights reserved. |
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