To machine helical gears at 45-degree angles, Gurecky Manufacturing Service Inc. installed a customized multifunctional machine from DMG Mori Ellison Technologies with a hobbing tool from Heimatec.
As the competitive nature within a market increases, so does the need for increased productivity and through put by handling the parts less. One way to meet this need is to accomplish more operations in one setup. Gurecky Manufacturing Services Inc. of Rosenberg, Texas, decided to enhance its manufacturing operations by purchasing a machine that could act as a regular CNC lathe and machine helical gears at the same time. However, a custom hobbing tool from Heimatec Inc. (Prospect Heights, Ill.) was necessary to achieve a desired 45-degree helix angle.
Gurecky was founded in 1983. Today, the company operates out of a 43,000-square-foot facility, serving the oil, gas and energy industries. The company produces multifaceted precision parts ranging from prototypes to mass production. To remain competitive, Gurecky constantly invests in advanced manufacturing equipment. For example, since buying its first DMU 50 ecoline from DMG Mori (Hoffman Estates, Ill.), the company has moved production from traditional vertical machining centers (VMCs) to the more versatile five-axis DMG Mori machines.
In late 2012, Gurecky President John Dorman decided it was time to purchase a CNC machine specifically for gear hobbing. The company approached DMG Mori Ellison Technologies and decided to install its customized multifunctional NLX 2500SY/700 with the ability to hob gears. What made this particular application challenging was the fact that Gurecky needed to machine helical gears at a 45-degree angle. This was a problem because standard hobbing units only allow ±30 degrees of helix angle adjustment due to loss of rigidity.
Undaunted by the task, Heimatec said it could design a custom hobbing tool with ±45 degrees of adjustment to use in conjunction with the new machine. According to Preben Hansen, president of Heimatec, lathes and their coordinating controls are more sophisticated these days, so a dedicated hobbing machine isn’t always necessary. “As long as the machines can handle it, we can build a tool to do it.”
After a few months of testing, the tool was complete and ready to be put to work. Rigidity is the key to tackling this difficult machining operation, he says. “It’s a pretty difficult operation, and when you’re twisting that tool, there’s a lot of leverage. You have to be concerned with the rigidity of the tool. When you’re turning at 45 degrees and milling at the same time, you tend to lose rigidity,” he says.
To combat this loss, Mr. Hansen says Heimatec’s hobbing units are designed with a strong bearing structure. In turn, this structure provides the rigidity necessary to reduce backlash and increase tool life. It also increases the performance of the hobs that do the cutting, he says.
Rexnord adds to its Autogard Torque Limiters with the XG Series
Rexnord’s Autogard Torque Limiters lead the industry in overload protection with proven reliability, dependable expertise and a broad range of options that offer bi-directional protection, lower total cost of ownership, increased accuracy of torque limitation, and longer life at high speeds.
The most recent update to the Rexnord Autogard Torque Limiter range— the XG Series —provides our best ever protection from unexpected torque spikes for extruders. Designed to disengage the driving motor from the extruder gearbox in the event of a process jam, the XG Series was developed based on over 30 years of industry experience in conjunction with leading machine builders and users. Able to instantaneously separate damaging inertias over a pre-set level and featuring easy-to-adjust torque setting, drop-out options, simple manual disconnection and disengagement sensors, the XG Series is the mechanical fuse for extruders.
“Rexnord Autogard Torque Limiters currently protect thousands of machines and production lines around the world,” says Rob Hucker, Product Manager of Shaft Management Solutions. “We’re particularly proud of our heritage in the extrusion industry and are very excited to be offering this new solution to improve extruder and compounding machine up-time even further.”
The necessity of bolted flange connection training
The Necessity of Bolted Flange Connection Training
There are numerous considerations for ensuring that a bolted flange connection (BFC) does not leak. They include damaged bolts and nuts, as well as flanges that are too far apart, misaligned or bent. Other issues involve sealing surface damage, improper lubrication, excessive piping loads, and excessive or insufficient bolt loads.
Additional considerations include debris on sealing surfaces, damaged gaskets, correct calibration and hookup of torque-limiting equipment, and proper tightening procedures.
Of these factors, nothing is as vital as the expertise of mechanics. No one is closer to the job or has a better opportunity to call out questionable conditions that can prevent a gasket from acquiring a successful sealing load.
Training ranges from on-site programs set up by company engineers to trial-and-error knowledge passed down from mechanic to mechanic. These educational avenues are valuable, but a complete training program that thoroughly covers the important topics related to successful installation of a gasket is rare.
Companies rarely can afford to commit the necessary resources to create and maintain an expert on this broad and detailed subject.
Given the numerous combinations of conditions, including the bolt-up procedure if one is used, that can prevent a perfectly good gasket from reliably sealing, how can someone know if a condition is acceptable? The connection must be tight enough to develop and retain a certain value of gasket stress but not so tight that damage results to any of the three primary flange components: gasket, flange and bolts. Installers need a complete understanding of the role and limits of the components so they can take suitable actions. A training program is available that provides all of this information.
The American Society of Mechanical Engineers (ASME) PCC-1-2013 document, Guidelines for Pressure Boundary Bolted Flange Joint Assembly, provides guidance on what conditions to look for and what actions to take as well as several time-tested tightening procedures. Unfortunately, it would be rare for a mechanic to have access to this information. Although this guidance is primarily intended for engineering resources, the first of several appendices are entirely dedicated to the training needs of mechanics, and many engineers would benefit greatly from such training. Additionally, it includes specific guidance on how to set up a training package and what should be included in it.
It was not until recently that a formal training program was developed that provides this information and results in an ASME Certificate of Completion that validates the training. In February 2016, ASME formally announced the launch of its Bolting Specialist Qualification Training Program.
Components of the Training Program
The training was the result of collaboration between members of an advisory group that collectively has more than 190 years of concentrated experience in preventing BFC leaks. These include mechanical engineers thoroughly grounded in the science of flanges, bolts and gaskets, as well as professional training resources.
The entire effort was managed by the oversight of ASME Training and Development. Its goal was to develop a comprehensive training program that would draw attention to the real-world practices and observations important to preventing leaks, as well as provide a clear understanding of why they are so important.
Forms of the Training Program
The training is provided in two forms: an online package and a one-day, hands-on session conducted by an ASME-approved technical professional. The online session is divided into four parts, which provide the majority of the training information. This form allows trainees to remain at their respective places of employment and proceed at their own pace. Graphics are extensively used to clarify concepts. At the end of each section, trainees can answer a series of true-or-false or multiple choice questions crafted to test a thorough understanding of the concepts. A passing score is required before moving on to the next part.
Part 1. Principles of Bolted Flange Joints & ASME PCC-1
This module provides a general introduction to the subject, focuses on the wide range of features important to the successful sealing and maintenance of bolted flange connections, and stresses the value of leak-free operation.
Part 2. Flanges, Fasteners & Gaskets
This section draws attention to the importance of understanding the role and limits of the three primary bolted connection components and how to identify mechanical flaws that can compromise the sealing of a connection. Central to this section is understanding how and why each of the three components interact with one another.
Part 3. Putting it Together/Taking it Apart
Critical to the successful tightening of a bolted flange connection is following an approved tightening procedure. As the temperature and pressure of a connection rise, the range of successful bolt loads can become very narrow. This section focuses on how to get it right the first time. Most important, this portion explains how and why a tightening procedure works.
Part 4. Bolting Safety & Tool Handling
Large forces are always involved in the tightening of a BFC. Safety is always the top concern, and the proper handling and use of high-torque equipment is especially important.
Figures 1 and 2 display some key concepts to understand. Figure 1 introduces the force-distance relationship that develops a given value of torque.
Figure 2 explains the consequences of varying values of gasket stress, discusses the importance of understanding both lower and upper limits of tightening, and points out how a combination of high pressure and temperatures can narrow the range of safe sealing gasket stress.
The hands-on session, which becomes available upon the successful completion of all four parts, is conducted at a specialized training facility. A wide range of training equipment and power tools is available to demonstrate proper equipment setup and use.
The ASME Certificate of Completion signifies the trainee has demonstrated an understanding of the material. Maintenance personnel with the certificate will have a matured sense of expertise to bring to the field. Improvement is grounded in nderstanding, and this training is intended to provide it.
Modern rock drills solve tough customer challenges
A Sandvik rock drill bit typically lasts for several hundred meters of drilling before it’s time to exchange it. But when a mining company in northern Sweden started mining for gold, the drill bit more or less exploded after just a few decimeters. The rock was extremely hard and abrasive – a true challenge for any tool on the market.
The customer turned to Sandvik who took on the challenge to develop an extraordinary tool, both tough and extremely wear-resistant.
“The customer asked for a drill bit that could drill one rod length, which is four meters – more than ten times the length it was capable of when they came to us,” says Christer Lundberg, Product Manager Rock Tools Tunneling, at Sandvik.
Raised front is key in our design of the new Sandvik top center drill bit, giving room for more gauge buttons and improving rock breaking.
Producing a drill bit that can last for four meters is not usually a demanding task, but in this instance the R&D team at Sandvik had to develop something extraordinary. A new bit design and Sandvik’s unique cemented carbide DP 65 solved the problem.
“Our customers know that we will go the extra mile to improve their productivity”
The R&D team continued to develop the drill bit and a completely new product, the top center drill bit, was recently launched, based on the lessons learned from the project in northern Sweden. The top center drill bit is now a standard product that can be used by all customers facing tool life challenges.
More powerful drills
Sandvik has a proud history of providing rock drilling solutions to customers around the world, making drilling safer and more efficient. Christer Lundberg mentions the R- and T-threads developed respectively in the 1950s and 1970s. These innovations made it possible to connect rods to each other and to drill more than one rod length at a time.
“These threads really improved productivity in the mines and later became industry standards,” he explains.
Modern rock drills are becoming more and more powerful. For Sandvik, this means that tools for these drills have to follow that development. Setting industry standards and continuously challenging them is the recipe for Sandvik’s success.
“Our customers can always rely on the quality of our tools and know that we will go the extra mile to improve their productivity with new tools and standards, says Lundberg.”
Sandvik Alpha, a further development of the R32 thread, meets the increased energy output, delivering straighter holes, higher penetration rates and longer rod life. Last year, Sandvik sold more Sandvik Alpha tool systems than the R32 standard.
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