This is the unedited transcript for webinar: Curved Motion System Design for Machinery and Automation.
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Hello, and thank you everyone for attending today’s webinar, Curbed Motion System Design for Machinery and Automation. Brought to you by Design World Magazine, and Bishop-Wisecarver. I’m Mike Santora, Associate Editor for Design World Magazine, and I’ll be your moderator. We’d like to thank our presenter Brian Burke for being here today. Brian Burke, Senior Project Manager at Bishop-Wisecarver group, is passionate about product development and manufacturing. With educational backgrounds in computer aided drafting, and design and manufacturing technology. He has more than 13 years of experience in the automation industry. An extensive knowledge from the production collaborations to product marketing activities.
Just a couple of housekeeping details before we get started. You’ll see several boxes on your desktop, all of which can be moved around to suit your preferences. Initially, the Q and A box is at the lower left, but this is where you will enter your questions for the Q and A session. Another box to note, is the additional resources. Initially at the lower right hand corner of your desktop. These resources are for your information needs. We also have a Tweet box right on the desktop as well as a list of hashtags for you to use. Feel free to tweet any interesting points right from there. Now, without further ado, here’s Brain Burke.
Thank you Mike for the wonderful introduction, and a special thank you to Design World for hosting this webinar topic today. I’m Brian Burke at Bishop-Wisecarver, and you can see the overview agenda today. You may not be familiar with Bishop-Wisecarver, so I’ll give you an introduction to our company, and the range of products that we manufacture. Before getting into our webinar topic, curbed motion system design for machinery and automation. This presentation has quite a few real world application examples of equipment and machinery using curvilinear products. We’ll take a look at standard and customized products for curved rotary, and curvilinear motion. We’ll look at how simple design concepts and principles, apply to these complex motion systems.
Bishop-Wisecarver Group is a women owned family of WBENC certified companies who works with manufacturers to engineer, and build linear and rotary motion solutions. Custom complex assemblies, and optimal embedded intelligence systems. It’s made up of Bishop-Wisecarver Corporation, Black Diamond Manufacturing, and WRW Engineering. Through these three companies, we integrate mechanical, electrical, software, and control systems. We have design engineering expertise, and 60 plus years of experience. We act as a single point of service, that results in custom designs for increased efficiencies, and accelerated time to market.
One of the ways to explain the products that we offer, is with our evolution layout. You can see these are components to complete systems. Looking at the left hand side, there are the component product lines, such as DualVee, individual guide wheels, linear tracks, and support motionings. Moving more towards the middle, our sub assemblies for linear guides, and so this would be our UtiliTrak product and our LoPro products. All the way over on the right hand side are complete systems, where these products are combined together with drive mechanisms, motors, and other accessories, including controllers and programming. If you look across the top, we have the T Race Products. T-Race is a family of products, and available through Bishop-Wisecarver. BWC is a North American distributor since 2015.
Bishop-Wisecarver is also the exclusive North American distributor of HepcoMotion products since 1982. Looking at a similar evolution layout, you can see that these products are available as components on the left hand side. Individual guide wheels, rings, and tracks. Also sub assemblies towards middle into complete driven systems over on the right hand side. This will be the focus of our topic today, this curvilinear motion solutions. Bishop-Wisecarver has several different core brands and product lines, and you may have seen these under promotions in Design World Magazine, or online from other sources. One of our most popular products is the DualVee guide wheels and linear tracks. These are component based linear motion products. LoPro is our linear actuator systems that have a variety of drive methods, belts, chains, lead screws, and ball screws.
UtiliTrak linear guides are compact, heavy duty linear products. MinVee’s are miniature, small linear guide. QuickTrak is a modular, t slot based linear guides meant for t slot frames and structures. MadeWell, low complexity linear guides including radio wheels, and crown rollers. We have a new addition to our products, Signature Motion linear actuators. There’s quite a few linear actuator products available from Bishop-Wisecarver.
In a similar fashion, HepcoMotion has several product lines as well. Particularly the GV3 product line, is their component based linear guide. They have some stainless versions in the SL2, ring and track systems in PRT2, and HDRT for heavy duty. They also have many different actuator products that we represent, including the PDU2, and the PSD product lines. All the way up to complete driven systems, like DTS or DTS2 inter ring and track. In general, the HepcoMotion products use 70 degree guide wheels.
To round out our product offering, let’s take a quick look at T Race. T Race makes linear guides, and telescopic guides of various designs. Two of the primary design features are the guide wheel based slides, and the ball cage base slides. These can be individual linear guides, or telescopic configurations. Our linear and rotary motion products are used by a wide range of markets and applications. You can see here a list of some of the areas in which these products can be effectively used. This just goes to show the versatility of guide wheel technology. This concludes the company overview, and the introduction of our product range.
I’d like to begin the webinar topic now; curvilinear motion solutions. Guided precision motion is most often thought of in the linear form. Which is used extensively in machinery and automation applications. The linear motion is only able to move in a straight line. Sometimes curve motion is better suited to an application. Rotary motion is the ability to move in a circle, such as in the case for turntables. It’s not always necessary to have a complete 360 degree ring. Some applications only require a few angular degrees of adjustability. Perhaps 30 degrees, 45 degrees, or 90 degrees. In these cases, a ring section, or curve guide is ideal. It’s possible to combine a linear guide with a curved guide to form a curvilinear solution. This provides for a very wide range of design options, from straight motion, to oval, or rectangular motion guides.
All of these products are based upon guide wheel technology. A guide wheel is a specialized bearing containing internal balls, or rollers, with vee groove outer diameter geometry. The wheels provide for the load carrying capacity. A rail, or track, is a linear profile with matching running surface geometry. Rings and ring segments are curved profiles, and are designed around the same shapes and sizes of linear rails. Therefore, it is possible to butt join a curved ring segment to linear rail. There are several distinct advantages to guide wheel based motion systems. The most important advantage is the wiping action, which is generated during use. The vee feature on the wheel, matches the vee feature on the rail. If you look at the running surface of the vee wheel, the area near the vee intersection is a smaller diameter than the area near the outer diameter.
Therefore, when the wheel rolls on the rail, there is a difference in peripheral speed. With each revolution, the inner vee area travels a shorter distance than the outer vee area. The difference in peripheral speed can be called a velocity gradient. As the wheel rolls, it is constantly wiping from the peak of the vee, to the outside. Naturally, this works well in clean environment, but the design is also an ideal solution for use in dirty environments where the self-cleaning wiping action is of the most benefit.
The second main advantage is the fact that the critical components, the ball bearings, are located internally in the guide wheel. They’re protected by seals, or shields, which keep debris out, and grease lubrication is provided inside where the balls roll on the internal ball raceways. These wheel bearings are lubricated for life, and do not require maintenance. Although it is recommended to provide light oil lubrication on the wheel to rail interface to lower the friction. Let’s compare this to recirculating ball linear guide technology, where the ball bearing roll directly on the exposed linear rail. Any debris must be removed by the wiper seals, and dirt ingress will lead to very rapid failure. There is no wiping action in a profile rail, and the seals must push the debris ahead of the balls.
Another advantage of guide wheel technology is the resulting motion. Very smooth and quiet operation is provided along with high load carrying capacity. High quality bearing grade steel is used in carbon steel and stainless steel. The metal is hardened so it won’t deform under heavy loads, and precision ground to excellent service finishes. The result is very low sticktion, and coefficient defriction. The wheel diameter is relatively large, there is very little resistance to get the wheel rolling. The materials and processing allow for industrial grade performance, which is suitable for continuous use. Perfect for automation.
One last advantage is the design of the eccentric bearing mount. This feature is used to adjust the set up and pre-load of the guide wheel to the linear rail. Adjustments can be made to extend the usable life of the system as the materials wear. The material hardness of the rail is generally softer than the wheel. The rail will exhibit the majority of the wear. When it becomes time to replace components, a new rail can be installed, and the old wheels reused. Contrast this to linear profile rail, where you can buy replacement bearing blocks, but the new blocks will be loose when installed on an old, worn rail. Therefore, to service a profile rail system, both the bearing block and the rail must be changed.
On guide wheels, a typical installation includes a mix of eccentric and concentric wheels. A concentric wheel is mounted as a fixed, non-adjustable data reference. The eccentric wheel includes a can feature for adjustability, and provides for fit up to the linear rail. Here is a comparison chart of the most popular guide wheel designs. The chart provides a relative comparison of several key factors, which might be useful when selecting a product for an application. You can see that all of the products are capable of providing good speed characteristics, but there are differences in the other categories. Here is a comparison chart of the most popular guide wheel designs. The chart provides a relative comparison of several key factors, which might be useful when selecting a product for an application. You can see that all the products are capable of providing good speed characteristics, but there are differences in the other categories.
The guide wheels are available with various internal construction, and external construction types. The most widely used products are studded wheel journals, where the bearing section is permanently attached to a threaded stud. These wheels mount using through holes. Standard wheel plates are available, or these can be attached directly to custom machinery. Another kind, is the blind hole type. These mount to a solid base into blind holes. Blind holes do not go all the way through a material. This is ideal when working with very thick mounting bases, or when you need to make eccentric wheel adjustments from the front side. There are several standard guide wheel sizes. These are the smaller wheel versions from HepcoMotion. You can see that they all have 70 degree vee running surfaces. The wheel sizes are based upon the outside diameter, and can range from 13 millimeters, up to 45 millimeters.
For these studded wheels, the mounting hardware is included. There are larger capacity guide wheels from HepcoMotion in their HD offering. These products utilize 90 degree running surfaces, and the sizes range from 64 millimeters, up to 150 millimeters on the OD. The largest capacity, a 150 millimeter guide wheel, is constructed with a double roll of rollers for very high load applications. A single, 150 millimeter bearing can support 50 kilonewtons of load, or around 11,000 pounds force. Since we’re looking at the heavy duty guide wheels, let’s look at the linear tracks starting with the heavy duty products. The linear rails are designed with matching 90 degree running surfaces. Several configurations, and feature additions are available. Spur and Henical Rack gear cut options can be added to the surface opposite the vee. An option key way can be added to the underside surface for locating during assembly.
There are two primary sizes, including 25 and 33, based upon the thickness in carbon steel and stainless steel. Note that the current wheel diameters can be used with the limited number of rail sizes. The primary tracks used in curvilinear motion systems are the double edged tracks. There are more size options for double edge rails, and you can see the chart for guide wheel compatibility. They are called double edged spacer slides because of the extra material below the top vee section. This additional material acts as a spacer so that the rail vees are above the mounting surface, which allows for guide wheel clearance. There are several standard section whits from 12 millimeters, up to 120 millimeters wide. Another type of linear track is the single edged spacer slide. These are used for linear motion applications where a much wider vee to vee installation is desired.
One reason to mount the vee’s wider apart is accommodate high moment loading requirements. Another interesting feature is the option to add a cut gear rack to the back face of one of the rails. This is a great feature, because the gear rack is cut parallel to the vee surface, which completely eliminates the assembly and alignment of separate components. These tracks are available in standard sizes, and are intended for use with each size of guide wheel, as shown in the chart. The last type of linear profile is called flat track. As the name implies, it does not have the spacer material on the underside. It is available in single vee edge, or double vee edge. These linear rails are lower cost, and lower weight. They’re also made from high quality steel, and hardened for durability, like the other tracks.
The key advantage of flat track profile, is that it can be rolled into a radius. Guide wheels are able to roll on curved tracks, and make for an ideal solution for machine doors. Here is an application example of machine doors guided on a rolled flat slide with V guide wheels. The large sheet metal machine doors move smoothly, even when exposed to processed debris, such as metal chips and fines. In this type of application, the concentric guide wheels roll on the top V edge to support the mass of the door. Eccentric guide wheels adjust upward to the lower V edge, and to adjust out any play. This provides a nice tight fit to the rail. Here is another application of vee guide wheels and flat slides used to guide machine doors. For this installation, the flat track is installed on spacers, and is not supported along the entire length.
This is a great solution because the gaps allow for processed debris to fall through. Similar to the last application, the guide wheels are mounted directly to the sheet metal doors. However in this machine, the doors move only in a linear fashion. We looked at the different rail profiles, and reviewed some of their key features. It’s important to note that all of these profiles are available in several precision grades. The precision is determined based upon the additional grinding operations. A P3 grade is sometimes referred to as commercial grade. These rails do not have any grinding, and are provided as drawn to shape. In many cases, a P3 precision grade will provide acceptable quality guidance. The P2 is ground on several of the key surfaces, including the locating edges, and the vee running surfaces.
This provides additional precision, and smoothness while lowering the friction. However, these operations add some cost. The P1 grade is the highest precision class, and is ground on more surfaces. The grind tolerance is very tight, and provides for high accuracy components with the lowest friction. There are pre-designed carriage plates for use with the linear rails. They typically contain four guide wheels, with two fixed concentrics, and two adjustable eccentrics. Blanking plugs are provided to seal the wheel mounting holes after assembly and adjustment. There are threaded holes for attaching to equipment. Many standard versions are available. The carriages for the linear rails are not compatible with curved ring sections. There are specific carriages capable of curve to linear transitions.
For curves of only one radius, and in only one direction, the carriages are called fixed sensor carriages. The last carriage type is a bogey carriage, which is capable of running on a variety of radii, and in multiple directions. For the rings and curved sections, there are many standard configurations, versions, and options. The pre-designed versions have matching cross sections to the linear rails, which allow for combinations of straight to curved motion. The rings have vee surfaces for use with the guide wheels, and carriage plate assemblies. The chart at the right shows some of the standard rings with double vee edges. The R number is to vee to vee size, and the second value is the diameter of the mounting bolt hole pattern. These are available in complete 360 degree versions, 180 degree, and 90 degree sections as standard.
Of course, any customized angle, or feature can be provided. It’s a little hard to see on these images, but there are options for adding gear teeth to the double vee edge rings. The gear teeth are added to the spacer section below the vees, and this can be done either on the outside diameter, or on the inside diameter. The drive pinion can turn the ring itself, and everything attached to it, or the pinion can drive the carriage around a stationary ring. One basic type of a ring is a ring disc. These are made from solid plate material, and are very useful as heavy duty turntable applications, or fixture requirements. They can have an optional gear tooth profile for pinion drive. The image at the right shows a part production concept, where the ring disc is used to drill angular holes in the work piece.
More typical, are the rings with hollow centers. We already took a quick look at the double vee rings, but there are some other standard options, including the internal vee ring, and the external vee ring. Both of these have vee surfaces on one edge, and flat surfaces on the opposite edge. There is always the option to add gear teeth to the surface opposite the vee. Gear teeth on single edge rings are very strong, because the teeth can be longer for more engagement to the pinion. Here is a quick look at the standard external vee rings that are available. Note the location of the drive pinion, and the supporting guide wheel bearings. As these pictures indicate, rings can be supported with the various wheel types, including the standard studded versions, and the blind hole types.
Just as a comparison, here are the standard internal vee rings. You can see the the drive pinion would be located on the outside surface. The load capacity of a ring system is determined based upon the size and number of wheel bearings. You need a minimum of three wheel bearings to support and constrain a ring. Typically you would use two fixed concentric wheels, and one or more adjustable eccentric bearings to mount the system. It is not recommended to exceed eight guide wheels total, because you cannot ensure that each wheel supports an equal amount of the load. Here is an application for vee guide wheel based rings. This one is from a trade show display used by a German automaker. They used a pair of double edged rings with internal gears to drive LCD screens in a circular motion. The screens are attached to the rings, and the ring assembly is turned. You can see that they used four each support bearings.
The stainless steel material, and precision grinding, make this application clean and exciting. Just a quick note here about the size restrictions. There aren’t any. Ring diameters up to about 1.8 meters are possible out of a single piece of steel. However, rings of any diameter can be fabricated in sections, and bolted together on backing supports. Very large motion systems can be produced and installed. The multi piece ring sections also enable standard transit. Imagine trying to ship a six meter ring. Here’s an example of some large ring applications produced in multiple sections. This is an illustration about how the ring sections are designed, and field assembled to a back plate structure. All sections are pinned for location, and bolted together. Very large assemblies can be produced using this method.
Here is a large ring assembly using the multiple section back plate assembly design. The ring has the external vee, and internal gear teeth. These are made to custom specifications, and there aren’t any standardized sizes. However, the standard guide wheels, and there accessories are designed to work. Here is an industrial application using a large ring in automated shrink wrapping of pallets. A rack driven carriage moves around the pallets of product to apply the plastic film. Now that we understand the linear rails and the ring sections, let’s combine them into curvilinear solutions. Some applications only require motion on a few sides. The profile is considered to be an open path. The carriage can travel along the path, but must reverse in order to return to the starting point.
Contrast the open path to the closed circuit. In a closed circuit, a carriage can take a complete path in one direction. When there are many carriages linked together on a closed circuit, many production operations can occur simultaneously to enable high through put automation. In order to obtain these motion profiles, we must join the straight sections to the curved sections. First, let’s look at the smaller track and ring sections, typically up to the R76 size. When a ring is meant to be attached to a straight rail, it’s important that they are designed and produced at the same time. This is because of the precision grinding process. The parts need to have accurate precision from vee to vee, so that they closely match each other, and the joints are as perfect as possible.
The other important consideration is the addition of the adjustment features. The joints utilize a steel key that sits inside the key way. Set screws are used from both sides, and jack against the key so that the precise alignment of parts can be accomplished. This method can be employed on all sections of a curvilinear solution. For the larger ring sections in the HD products, a similar solution is used. The ring and linear profiles typically mount to a back plate support for clearance. Joint blocks, and locating pins help to align to the key way. Jacking screws are also provided for precise alignment for the sections. These can be produced for very large applications. An example is shown of an actual assembly with the man for scale. The background photo is edited out, but the man is real and is not scaled.
Let’s take another look at common configurations. We mentioned the open profile briefly before. This design is where a curve and straight do not follow a complete loop. Of course, the sections are joined together in the same fashion. Let’s look at some applications. In the image at the right, you can see heavy duty open profile using the commercial grade guides. The commercial grades are not precision ground, and in most cases can provide adequate precision. In this system, the motion is provided by a rack driven carriage assembly. You can see the blue drive motor attached to the carriage. The gear teeth are located below the double vee edges on the spacer section. You might be wondering, can the gear teeth go from the straight to the curve? Yes. The gear profile can be made to follow the profile.
Here is another open profile application. This one is also an L-shaped track design to support an air powered drill used to assemble door and window fittings. You can see how the tool is precisely guided around the work piece. Motion is provided by manual means. For our last example of open profile guided motion, here is a machine controller mounted to an overhead rail. This is also an L-shaped assembly, which is moved manually by the operator so that they can see and control the machine from various vantage points. The most popular type of curvilinear motion is the oval system. We call this a ring and track configuration, because they are comprised of two 180 degree ring segments joined to linear track. Specific diameters are pre-designed, but the straight sections can be of customized length. As we discussed before, there are many standard sizes and diameters of rings to suit a wide range of applications.
This is a pipe fabrication application where a cutting torch operation is automated using a ring and track system. The machine is simple. The assembly is attached to the pipe, and a neumatic tool drives the pinion around the oval shape. The cutting torch is guided vertically on additional linear guide bearings. The cutting torch traces out the pattern to cut the hole into the pipe. The ring and track motion system can be driven using a variety of methods. The most common method is to use timing belts. Looking at the left side, you can see that the guide rails are attached to aluminum extrusion as the base support structure. The carriage plates can be driven around the oval shape when attached to a power transmission belt. A main drive pulley and an idler pulley, are available to provide the motion.
There are several carriage designs, and a few attachment methods for the belt. The carriages in the image are moment load carriages, which have additional support bearings for high downward forces. The image also shows the carriage locking mechanism, which can greatly improve the positioning accuracy of the carriage at specific locations. These complex motion systems are often indexed to multiple work stations, and then paused for robotic operations to occur. This machine is a trade show example of automation, but the implications are very real. In this case, the equipment is used to apply barcode labels to box packaging at high speeds. The small oval system is for demonstration purposes, but in a real automation environment, the products could be assembled and inserted into the box packaging. Equipment of this type is capable of continuous operation with very short cycle times.
In order to accommodate space for the necessary production operations and equipment, sometimes the ring and track system becomes very large. The systems shown here is still under the assembly process, but you can see the large number of carriage plate assemblies. A system of this size is capable of very high productive through puts. This is an application example of the automated assembly of electrical components. The main mechanism is based upon the belt driven ring and track system. They did not use the standard carriage plates however. Instead, they used modified carriages, which function as work holding fixtures. Here is another example. This machine is a great example of continuous production of numerous operations. The machine processes reads for wind instruments, and completes all of the production steps.
Blanks are loaded into the machine using a vibratory bowl feeder. Several milling and sanding operations are completed. The machine designer created their own drive mechanism based upon steel chain and sprockets. The next slide is a video of this application in operation.
Automotive production typically requires large quantities of parts with complex operations. The system, shown here, is used to assemble shock absorbers. You can see the large number of parts in production. The system indexes to various work stations where the assembly operations occur. The next slide contains a video of another automotive assembly application.
Leger ring and track systems can be created when using 90 degree corners. The end result is rectangular system. There is one primary drive pulley, and the others function as idlers. These motion systems can be quite large. This system was made to package razor blades for a well known international brand. The system includes the carriage locking system to ensure accurate positioning at each work station. Notice the second rectangular system in the background. In some applications additional operations can occur on a secondary processing loop. Perhaps some processes have longer cycle time, or additional components need to be prepared in a queue. Robotic transfer can occur between the motion systems.
A newer version of the driven curvilinear motion system utilizes belt linked carriages, driven by a scroll. The bearing on each carriage engages the spiral of the scroll, and is pulled through. Several carriages are engaged in the spiral at the same time, and the rest of the carriages are linked together like a bicycle chain. The scroll itself, is driven by a timing belt to the motor. The scroll provides a very strong, accurate, and dynamic drive. These systems have fewer overall components compared to the previous version, resulting in a lower cost. It can also have higher driving forces in higher speed for more rapid indexing. These can be made in oval and rectangular configurations. However, there are a few downsides. Very long system lengths with more than 40 carriages, an additional scroll drive may be required. This technology can provide positional accuracy of 0.2 millimeters, or about eight thousandths of an inch.
With the addition of the carriage locking system, you can expect to see plus or minus, 0.01 millimeters, or around eight ten thousandths of an inch. Here are some images of scroll driven systems. The scroll itself is made of durable polymer material, which is machined to the specific pitch of the carriages. The system on the right includes the carriage locking system for the higher accuracy positioning. You can see that the belts are located over the center line of the rail, or guide way. This allows for the elimination of the drive in idler pulley assemblies, and bearing cartridges.
Some additional views are shown here. The image at the left shows the side of the carriage where the bearing is mounted. This is the bearing that engages with the scroll drive. The upper right image, shows the carriage bearing as it begins the engagement. When there needs to be multiple drive scrolls, such as in the lower right image, both can be driven from a single motor. The dual scrolls can be timed together using belts, so that they ensure synchronous rotation. The next slide is a video demonstrating the scroll drive in action. You can see that it provides very smooth motion, and then after that, another video will show the rapid acceleration, and indexing capabilities.
The final application that I would like to share with you today, is from the automotive industry. This machine is used for an automotive headlight ceiling application. It has 24 fixtures, which can be positioned so that component placement operations can occur. Each fixture is mounted to the movable carriages. They all index together, and multiple assembly operations occur at the same time. The rectangular shape was needed to position the equipment in the center area of the machine. Dual scroll drives are belted together to provide the motion.
This concludes the main content of our webinar today. Today we looked at curve motion system design for machinery and automation. We reviewed many of the standard and customized products for curved rotary, and curvilinear motion solutions. We saw how some of these designs are very simple, and the concepts and principles can build into complex motion systems. Of course, we sprinkled it with many real world application examples of how these products are used in automation. Today we also included a quick overview of Bishop-Wisecarver Group, as an introduction and the range of our products. As always I would also like to thank Design World Magazine, and our host Mike Santora. Thank you.
Once again, thank you Brian. For all of our listeners, just a reminder that this webinar is available at designworldonline.com, and by email. You can also tweet with #DWWebinar. You can also connect with Design World through any of your favorite social media outlets, Facebook, LinkedIn, Twitter, and so forth. Lastly of course, you can discuss this on engineeringexchange.com. Once again, thank you everyone for attending this webinar from Design World.