Take the pressure off boring critical areas

Figure 1. The multiple-tooth design of a controlled boring system provides a high degree of tooth-to-tooth face contact area throughout the entire operating stroke.

The following article is adapted from Alex Seath’s presentation, “Controlled Boring Techniques for the Oil, Gas, and Valve Industry,” presented at TOYOtech 2017: Oil, Gas & Valve Symposium held by JTEKT Toyoda Americas in September.

For over 30 years Innovative Tooling Solutions (ITS) has been working with original equipment manufacturers of oil and gas equipment and their subcontractors across that produce parts with some unique machining difficulties.

Many features within valves and associated connectors for this industry require machining metal-to-metal sealing faces. These faces can be tapered in design or internal to the component, and they have the added complication of tooling entry through a small bore and then an expansion of the tool to create an internal feature like a seat pocket or tapered seal. These features also can require extended tool lengths for which modular tooling and various supports are needed to accommodate the longer reach.

In many cases, because of component size and shape, manipulation and cutting rotation of the component add to the overall machining challenge.Tooling must be able to accomplish cutting rotation and diameter change while machining very precise diameter, surface finish, and positional tolerances. In particular, the flatness associated with high-pressure seat pocket areas is vital, with the radial straight line displacement of the cutting insert being a critical element to achieve this. A precision-hardened and -ground, multiple-tooth interface between the tool’s internal actuator and the radial side movement has provided reliability, repeatability, accuracy, and strength for these applications (see Figure 1).

High-pressure coolant, delivered via an internal tool design, provides multiple, controllable fluid outlets at the cutting area to lubricate the carbide cutting insert and aid in clearing chips from confined areas (see Figure 2), adding to the overall process control.

More Range and Flexibility

ITS tools for this industry fall into two main categories: those with contouring heads (CH) and controlled boring systems (CBS). Both tooling categories are designed with an added axis to provide CNC diameter control while the machining process is taking place.

The extra axis allows the machining of tapered radii, multiple diameters, and threading to be completed in a single operation. The radial movement of the cutters can be precisely controlled by the lateral motion of the machine’s moving spindle. The need for multiple fixed tools with individual settings is dramatically reduced (see Figure 3 and 4).

Large Diameter Range

The CH was adapted to the horizontal boring machine platform several years ago and is still in use today. Applications include machining of face grooves, valve outlet profiles, internal valve seat angles, and undercut cavities, plus overturning of valve flanges and external locking taper features associated with single cavity and composite valve blocks.

The CH provides a large diameter range and flexibility in which the extra axis of radial slide motion operates and actuates outside of the workpiece. Proprietary boring and turning tools that incorporate quick-change systems are used to extend the reach of the contouring head into or over the workpiece. Counterbalance mechanisms for large-diameter machining also are employed to ensure accuracy (see Figure 5).

Figure 2. Coolant flow to the cutting area can be controlled and outlets for coolant to assist with chip removal can be open or blocked.

Cutting End Motion

The CBS differs from the CH in that the extra axis of radial slide motion is located at the cutting end of the tool, which operates and actuates inside a workpiece. Valve seat pocket geometries, bonnet cavities, and outlet angles and profiles for single cavity and composite block valves are the main application areas. Tubing hangers with internal offset bore profiles, Otis®-type--or corrugated--profiles, and VAM® tapered cylindrical threads also are machined with CBS-type tooling (see Figure 6).

Roughing, semi-finishing, and finishing machining of materials such as carbon and stainless steels and INCONEL® alloy overlays associated with oil and gas valves can be performed in one setup using CBS tooling. The high levels of tolerance, surface finish, and the critical area of seat face flatness associated with the sealing and operation of oil and gas industry valve designs can be achieved.

Modular designs with pilot-type supports accommodate producing components with extended lengths, with ratios up to 20-to-1 (see Figure 7). Both single and double insert toolholders can be used to increase productivity depending on component requirements. Automatic tool change is possible with the engineered combination of machine and clamping interface.

In recent years, as the fracking valve product industry has grown, both CH and CBS tooling have been used for the internal machining of undercut profiles and to meet the quality requirements of tapered seat details required by these valves (see Figure 8).

In addition to providing a controlled machining envelope, the tooling offers flexibility to allow the manufacturer to develop the machining process around the product to achieve maximum efficiency. This saves time and money and provides a fast payback on tooling investment.

Alex Seath is general manager, Innovative Tooling Solutions, 855-642-1057, www.itstooling.com.

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