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Finding and implementing the perfect end effector system depends on the user's proper consideration of four key areas. Only after fully understanding the needs of these four areas can an educated end-effector choice be made.
In recent years, the robotics industry has undergone a significant demographic shift. Traditionally, the advantages of robot use have been combined with industrial applications, but the use of non-traditional robots has increased significantly. The most popular are customer service robots, personal assistant robots, unmanned aerial vehicles (or drones) and so-called "unmanned" vehicles. Although the pattern has changed, industrial robots will still be an important part of this market. Some people predict that by 2025, the market's sales revenue will reach 500 billion U.S. dollars.
For example, one of the industries that will continue to rely extensively on robotics and automation is automobile manufacturing. The industry was one of the first to adopt robotics/automation as a way to improve and optimize manufacturing time and planning. Other industries that will continue to benefit from automation work include the packaging, pharmaceutical, and aerospace industries.
Having said that, there are still manufacturers and many other manufacturers in these industries that can further enhance their experience in automation applications. Two industries that are easy to think of are metal stamping and metal assembly industries.
In the metal stamping industry, there are many commonly used stamping line styles, and parts are formed on the stamping line, including:
Progressive: Progressive press lines are used to run smaller parts that do not require automation or end-of-arm tools (EOAT) to move from one mold to another as the part advances along the production line. EOAT acts as the "hand" of the robot because the part is fixed in place or moved to the next station during the manufacturing process.
Transmission: These types of press lines have three-axis transmission rails, which can transport parts from mold to mold, and are powered by machinery or servo motors. The mechanically driven transmission line has a fixed movement relative to the punching time of the press, while the servo-driven transmission allows the movement to be programmed and ultimately optimized to achieve the best throughput or strokes per minute.
Tandem type: The tandem type has a series of presses, usually between four and seven, arranged in a row. The part transfer process in tandem presses is usually configured as a three-axis pick and place system or by a six-axis robot located between each individual press.
Regardless of the type of stamping line used, remember that stampings are not always complete parts. In many cases, stamping parts need to be welded or assembled before they become finished products. These requirements transform metal stamping parts into a metal assembly process. In this case, robots and robot EOAT play an important role in ensuring the efficiency and accuracy of the metal assembly process.
Now that we have identified and defined the different types of press lines available, the rest of this article will focus on the four key factors that must be considered in order to optimize automated or robot-dependent press and body shop operations. It will also provide guidance on how to choose the best automation tool or end effector suitable for the operating conditions.
Imagine joining the 100-meter sprint from standing at the 25-meter mark when all the other runners are running past. Or enter Indy 500 after 20 laps in the remaining fields. In this case, winning the game is almost impossible. This is often the case with end effector suppliers of new workholding or pick-and-place systems.
The traditional mold design process requires the end user to first cooperate with the mold manufacturer to create a mold design that will be used to manufacture the required parts. After several review and revision stages, the end user will approve the mold and create a CAD drawing of the mold. At this time, the supplier of the automation tool will be selected and the agreed mold data will be received. Using this mold date information, the mold supplier will create mold design and work simulations for automated molds. After reviewing the user, a corrective action report (CAR) will be formed to record any gaps or collision issues that occurred during the simulation. The CAR will be sent to the mold maker, who will resolve any gaps or conflicts before shipping the mold.
To be fair, the reason for this mentality becomes obvious when you realize that the cost of a well-designed and fully functional mold set can be as high as $200,000, and the cost of an end effector is usually less than 10% of the upfront cost. Although it is understandable for system designers and end users to focus more attention on the more expensive components, all components in the system-no matter how large, expensive or cheap-must work in perfect harmony to create A fully functional and reliable system. Therefore, if the automation tool supplier participates in the design process earlier, expensive time and rework of mold modifications can be avoided.
Therefore, the end effector supplier is usually allowed to incorporate into the design process where finger tools or EOAT are required after receiving a flow sheet with suggested gripping points and/or gripping points. In order to catch up, the end effector supplier will design the contact points of the system, simulate the required movements (clamping, lifting, pitching, loosening, etc.) and cooperate with the mold manufacturer to ensure that the end effector and the system work in harmony. Molds that have been produced. The mold maker will determine whether the mold and the end effector are compatible and able to meet the needs of the end user. If modifications are required, a corrective action report will be created. After completing all modifications, a simulation will be performed to see if the system can perform as expected.
From a macro perspective, it seems necessary for end users and system designers to include EOAT suppliers at the beginning of the design process due to all the necessary back-and-forth relationships between the mold and the end effector selection area. In fact, due to the advancement of digital design capabilities and forward-thinking manufacturers reconsidering the openness of the traditional way of doing things, a “one-time-for-all” mentality of relying on robots for workpiece clamping and picking and placing has begun to stand firm. heel.
Finding and implementing the perfect end effector system depends on the user's proper consideration of four key areas. Only after fully understanding the needs of these four areas can an educated end-effector choice be made.
There are two basic industrial manufacturing environments that will use parts handling systems that robots rely on. they are:
Stamping shop: Generally speaking, the stamping shop is the place where the traditional parts stamping process is performed, although the definition of the stamping shop has been developing in recent years. The old setup has a so-called "transfer press" operation, which is a linear operation that relies on non-robot automation. However, more and more press shops are beginning to add "tandem" production lines to their facilities, which use robots to perform various functions. Therefore, the end effector in the tandem production line needs to be compatible with the robot.
Body workshop: In the body workshop, the stamped parts are joined together by welding, gluing, etc. The body shop is a facility that relies on robots, and its modular end effector system is developed to meet the needs of specific applications, most of which require precise positioning and clamping of parts.
Regardless of whether the end effector system is used in a press shop or a body shop, three main operating parameters should be evaluated and quantified before selecting the best end effector. they are:
Cycle time: In the press room, you will find the cycle time in strokes per minute (spm), which is the number of parts stamped per minute. In Body Shop, it is the end effector system that can be executed to complete the movement or operation of the part. For example, a typical multi-station printer can run at a speed of 15-22 spm. The efficiency of the system design helps to increase the spm rate. In addition, advances in digital design and simulation capabilities now allow mold and end effector designers to conduct interference studies, which can point out potential bottlenecks in the movement of parts. These bottlenecks can then be designed before the system becomes active, which helps optimize its spm capabilities.
Weight: The weight of the part to be moved plays a huge role in determining the type of end effector that can be used. The designer of EOAT or finger transfer must understand that the tool needs to be designed to be as strong and light as possible so that it can operate reliably without falling, vibrating or misaligning, and being able to handle many thousands of transmission cycles without fatigue Or crash.
Scope: How far the end-of-arm tool must extend to perform its required task will also determine which end-effector solution is best for the job. It is best if robots or automation can reach or travel as much distance as required. The idea here is to limit the offset load and/or weight of the EOAT or transfer finger. Keeping the EOAT or shifting finger as small as possible (minimum offset load) will help reduce deflection, resulting in a better automated rhythm and more efficient throughput.
Now that we know the type of operating environment and operating parameters that the robot-driven end effector system will encounter, it is time to consider the construction method of the type of end effector that can be deployed.
There are basically two options. The first is a modular tool, which is gaining use and acceptance. This option requires less design time because the end effector can be built from a standard library of CAD components. This leads to better design consistency and provides greater flexibility when the product design needs to be changed. By using standard designs and components, modular tools require fewer customized parts, thereby reducing assembly time. If a collision occurs during operation, the total weight of the finished product will be lighter, the startup time will be shorter, and the recovery speed will be faster.
The second end effector design option is a more traditional welded structure. Although this approach brings a high level of durability and reliability, its design and operating characteristics pale in many respects when compared to the design and operating characteristics provided by modular tools. Since this method has fewer standard components in the CAD library, it may take longer to design the end effector. This also makes it more difficult to consider or predict future design changes, and there may also be differences between design teams. Building a welded end effector may also require more custom parts, which may result in longer assembly times. The end result will be heavier components and a correspondingly longer start-up time. The failure recovery time of welded parts may also be longer.
Finally, there are auxiliary components that can be used with the end effector system to consider. these are:
Vacuum cups and magnets: These are the components that actually contact the parts or finished products that need to be held or moved. Vacuum cups are the most popular in this task, with various sizes, shapes, treads, flexibility, and structural materials-the most common is rubber, although polyurethane has made some progress in the market-and the combination of vacuum sources Connection, usually Venturi. Magnets are often used in applications where the surface area is insufficient to reliably and safely pick and place parts with vacuum chucks.
Holder/power clamp: You can use sheet metal clamps or power clamps to clamp parts. Lightweight sheet metal fixtures are ideal for parts handling applications in the press shop. The internal mechanism of the holder prevents it from opening when air pressure is lost. Sheet metal fixtures have multiple fixture styles and multiple contact point options. When handling parts in the Body Shop, power clamps are often used. They have a closed pneumatic toggle lock, even in the case of loss of air pressure, the power clamp with integrated on/off sensing can hold the parts.
Venturi tube: The venturi tube has gained global recognition as the main source of vacuum to the vacuum cup of the end effector system. The traditional system uses two lines to run, one creates a vacuum to allow the parts to be removed, and the second adds air to the cup to cause the parts to fall. However, the new single-wire venturi is becoming more and more popular. The air volume required for a single-line venturi is reduced by 50%, thereby reducing operating costs, and only one air line needs to be maintained, thereby reducing maintenance costs.
Although the overall market demographics may change, the use of robotics in workpiece clamping and pick-and-place applications in industrial manufacturing will not be as fast as a dinosaur. For industrial manufacturers who use automation/robots in press shop and body shop operations, it is very important to design and deploy automation tools/end effector systems that are compatible with the automation/robots used. The best way to do this is to involve the automation tool/EOAT supplier in the design process from the beginning, understand all the variables and options at play, use the latest digital design technology and work hand in hand with everyone. Party.
About Benjamin Pauzus, Jr. Benjamin Pauzus, Jr. works in the end effector business development department of DESTACO in Auburn Hills, Michigan. You can contact him at bpauzus@destaco.com. DESTACO was founded in 1915, formerly known as the Detroit Stamping Company, and is the world's leading supplier of precision motion, positioning and control solutions in the industrial automation field. DESTACO series products include industry leading brands such as DESTACO manual grippers, power grippers and end effectors; Camco™ and Ferguson™ indexers; Robohand™ grippers; and CRL™ manipulators and transmission ports. The company has approximately 800 employees in 13 locations around the world and is part of Dover Corporation. For more information, please visit destaco.com.
DESTACO is now a global leader in the innovation, design, manufacturing and support of clamping, grasping, transfer, indexing and robotic tool solutions that meet the needs of workplaces and automation.
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