Achieving True Press Alignment with Precision Laser Tracking
Proper press geometry and alignment is the key to promoting tooling life, proper press operation, producing quality extrusions, and minimizing maintenance down time. However, many extruders find it difficult to maintain alignment on their presses. Wear on bushings and wear pads can change the position of the moving press components, and fatigued or yielded press frame components can alter press alignment. In addition, unknown conditions such as press frame geometry can affect the alignment of the extrusion press.
BTS uses a Laser Tracking system as a precision measuring tool used for large scale and finite measuring. The system uses a rotating tracking laser head unit that tracks a variety of precision machined laser receivers. These receivers are designed to measure surfaces. Additional attachments allow for bore and depth measuring. As the receiver is moved over a surface, bore, or depth, the software records thousands of measured data points in the X, Y, and Z coordinates. This enables the user to measure complete surfaces, cylinders, and fixed points on an extrusion press. Once the measuring is complete, the user generates a “step” (.stp) file that records all of the measuring data. This file can be uploaded into engineering software such as SolidWorks. With some minor additional input from a designer or engineer, an accurate 3D depiction of the extrusion press frame and components can be modeled.
When aligning the press components such as the moving crosshead, stem, and dummy block relationship to the container, the measuring system can provide accurate data to correct alignment. The laser measuring equipment can be attached to the moving crosshead and container housing to verify motion in all three coordinates. This can assist the extruder in determining the correct course of action in aligning the components to the correct press centerline.
The extrusion press frame geometry should include accurate tie rod lengths between the main cylinder housing and platen to establish parallelism and perpendicularity of the press frame. When the press geometry is correct, the press frame will equally distribute the loads across the tie rods and into the housings. Incorrect press geometry can cause undue fatigue in the tie rods that create high stress concentrations to the housing or platen. Therefore, correct extrusion press geometry is critical to prevent loss or damage to the major press components such as the tie rods, main cylinder housing, and platen.
Press Component Alignment
Extrusion press alignments have been executed using a couple of different methods. Alignment tool systems or taper gauges at the container can verify container alignment to the dummy block and stem. Many extruders still rely on “eyeballing” it. Since there are clearances within the tooling, many of these practices are acceptable. However, as we have learned with some of the new measuring technologies, these practices will only get an extrusion press close to correct alignment. An optimized extrusion press that is aligned to the press frame centerline will operate as engineered and designed. Properly aligned press components reduce tooling wear and can prevent flashing at the die face.
Determining Operating Extrusion Press Centerline
Precision laser tracking measurements can determine the optimal press centerline based on wear. Adjustments can be made at the main cylinder and stem to level the cylinder ram travel and provide a straight operational centerline. Once the main cylinder centerline is determined, the container housing and container is adjusted to match the centerline of the main ram. This process of aligning the press components will assure the press operator that the press is operating on a correct centerline and reduce undue wear on the press tooling.
Additional Extrusion Press Measuring
Precision laser tracking measurements can also be useful when replacing or changing various press components. Some of the critical areas of an extrusion press include the stem mounting, container installation, and die positioning. When mounting the stem, it is important that the centerline of the stem is in line with the centerline of the main ram. 3D measuring allows for accurately locating the stem to the main ram. Considering that the entire press tonnage is transferred through the stem, proper mounting is paramount to proper press operation.
Containers are typically held in place by a series of keys and keyways. Over time, these components can become compromised and place the container out of alignment. Verifying the positioning of the container can be accomplished when the press is not operational. In turn, these measurements can determine the positioning and wear on the keys or keyways. Stem to container alignment is critical for maintaining the tooling and safe operation of the extrusion press.
With 3D laser tracking positioning equipment, an extrusion press can be optimized for production, maintenance, and safety. All extrusion presses produce a tremendous amount of force. Worn or poor press geometry can reduce the operating capabilities of an extrusion press. Correcting an extrusion press can assist with optimizing the press performance and reduce the likelihood of potential failures that can create dangerous situations.
BTS’s heavy-press division has 30+ years of continued experience developing solutions for a breadth of extrusion production components. In fact, many presses currently in use in the industry were fundamentally based on our lead engineer’s design! Learn more about our Heavy Press Division.
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