Toothed Belt Axis For Compact Pick & Place System

2023 Author: Hannah Pearcy | [email protected]. Last modified: 2023-06-01 01:49

Laser marking has several advantages compared to other marking methods - for example, the consumption costs are lower and the maintenance costs are lower. But above all, it is a possibility to mark components made of very different materials very quickly. "In order to make full use of this time advantage with large quantities, the workpieces must also be able to be fed into the laser quickly," says Thomas Hettich, product manager at IEF-Werner from Furtwangen in the Black Forest.

He is thus addressing a project in which a tool manufacturer turned to the automation specialist with precisely this requirement. The task: Drilling tools with shank diameters from 3.5 to 25 mm made of high-speed high-speed steel HSS-E and solid carbide (VHM) should be removed from the customer's workpiece carriers one after the other, fed to a marking laser and then placed back in a workpiece carrier - and this extremely quickly and precisely. "Tools with shank diameters of less than six and from 16 millimeters are labeled on one side, the sizes in between on both sides," explains Hettich. The complete handling had to be done fully automatically.

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Feed components efficiently

The Pick & Place system is based on the expandable Posyart belt system. The modular system contains many standard components which, according to IEF Werner, can be used to solve almost all tasks in the transfer, assembly and logistics areas. The main components such as belts, drives, switches or stop elements are said to be very durable. The dovetail geometry on the long sides of the profiles is intended to allow sensitive, stepless positioning of the attached assemblies.

"We have equipped the system with receptacles that the customer's workpiece pallet (WT) can carry," says Hettich. Side positioning, centering station as well as a lifting and turning unit put the WT in the right position. They are placed in the center of the centering unit and then fixed three-dimensionally with an accuracy of ± 0.05 mm. The stoppers are arranged centrally. This is to prevent the workpiece carriers from tilting in the guide rails. The tool manufacturer has provided the WT with a data matrix code for this application. This code hides information about the tool holder type, the number and the X / Y coordinates of its holes, the shank diameter and the holder height.

Workpiece carriers must be identical

At the system, an employee places the WT with the drills on a basic carrier of the webbing system. "It is imperative that the workpiece carriers are identical in construction within an order," emphasizes Hettich. At the control panel, the employee enters the order, the number of WT - and whether the drills to be marked have a clamping surface or not. When the system is started, the system first reads the labeling data for the laser. A scanner recognizes the data matrix code and the webbing system moves the WT to the removal station. There it lifts the WT from the webbing and centers it. The linear unit traverses the grid of the respective tool carrier type in the Y direction. The linear unit now positions the workpiece carrier in such a way that a laser measuring system detects the first line of the tool holder. A distance measurement detectsin which grid position the tool currently being machined is located. The sensor transmits this position to the control.

For the different drills, certain cycle times for handling are specified depending on the labeling duration. "For tools made of HSS-E, the overall process should be 14 seconds for single-sided and 14-sided labeling," explains Hettich. "It takes four and eight seconds for the solid carbide tools."

Handle in the kit

To implement a suitable handling technology, the IEF engineers constructed a positioning system from standardized linear units. The developers have a wide range of automation components at their disposal with which they can design processes very efficiently, according to IEF Weerner. This includes various linear axes that are selected depending on the requirements for dynamics, precision, repeatability or also for speed.

"With our linear axis systems and the standardized connecting elements, we quickly and inexpensively created a suitable positioning system that is precisely tailored to the task and the space available to the user," emphasizes Hettich. Central to the implementation of this system were the overall length and the drive concept of the linear axis on which the two gripping units travel.

Two sledges on one axis

Due to these general conditions, the 160/15 G module is used. According to the manufacturer, the "G" variant is characterized in that the toothed belt axis is equipped with two independently movable slides. Two separate toothed belts are driven by independent motors. This should save considerable installation space: “In order to achieve the required cycle time, two linear units would have to be arranged side by side. With the drive concept, one unit is now sufficient,”says Hettich. The 160/15 G module is positioned in such a way that a gripper unit is attached to each slide, which reduces the installation space required. "This allows us to quickly get the components to the actual task, laser marking," explains Hettich.

This is done as follows: The first gripper moves to the removal position, takes the corresponding drilling tool from the workpiece carrier and transfers it to the laser station. After a few seconds, the drill is labeled. While the first gripper is already on the way to the next drill, the second gripper takes the marked tool and moves it to the empty WT on the opposite side of the removal station. For the Y movement, the two grippers are mounted on precise linear adjustment units with toothed belt drive of the module 68 type.

Transfer with belt axis

Because the first gripper rotates the component by 180 degrees in the case of two-sided labeling, an additional module of the type 68 D is used for this. This is equipped with an axis of rotation designed as a hollow shaft. The torque of the motor is transmitted to the axis of rotation via a belt transmission. The angle of rotation is 440 ° - with maximum repeatability, as the manufacturer emphasizes. The component is also light and particularly compact. Any pneumatic hoses and control cables could also be integrated into the hollow shaft - which makes the system even more space-saving.

This rotation is not only important for marking on both sides. “If the standard tools have clamping surfaces, the system recognizes this and determines their position,” explains Hettich. The first gripper then turns the drill on the way to the laser station so that the label can be attached in the required angular position to the surface.

IEF-Werner delivered the complete system. This includes not only the linear and adjustment units, but also energy supply systems, motors, cabling and hoses. "We were able to fully meet customer requirements with the implementation of this system," says IEF product manager Hettich. It is not only compact, the user also achieves extremely high cycle rates. The laser is practically non-stop in use. (jv)

Motek 2017: Hall 5, booth 5220

Handling systems

This way, handling systems can be set up easily and flexibly

* Thomas Hettich is product manager at IEF-Werner GmbH, Furtwangen.