2.2.2 ATC Chain
Small conveyance: Machine tools
ATC Chain is used to organize tools in the automatic tool changer, which is a device on Computer Numeric Control (CNC) machine tools.
When fewer than 30 tools are used, the tool pots are mounted on a disc. Tools are changed by controlling the disc. When more than 30 tools are used, tool pots are mounted directly on the chain. (See Figures 2.11 through 2.13.)
Comparing the disc and chain set-ups, differences include the following points:
- Using the same area, the chain type can have as much as 1.5 times as many tools as that of the disc (Figure 2.13).
- To add tools to the disc type, you must change to a larger-diameter disc and redesign the changer. But with the chain type, you simply add chain strands. The changer location remains the same, allowing standardization. (See Figure 2.14.)
Figure 2.11 ATC Chain Can Accommodate Many Tools
Figure 2.12 ATC Chain
Figure 2.13 Chain-Type ATC can have 1.5 times that of Disc-Type ATC
Figure 2.14 Ways to Add Tools
Construction and Features
There are two types of ATC Chains: SK and HP. Note the following features:
SK series has two strands of chain in which the pitch of the outer link and inner link is different. SK attachments are placed on every other link. There are three standard tool pitches: 95.25, 114.30, and 133.35 mm, which are based on RS100, 120, and 140 transmission chains, respectively. The SK series can bend in only one direction.
HP series has large-diameter hollow pins. There are five standard tool pitches: 90, 100, 130, 140, and 160 mm. HP series can bend in both directions, which permits more freedom in design.
Both types of chain are available for any shank number, including 40 and 50 in MAS, ANSI, and ISO types. Special ATC Chains are also available for 25, 30, 35, 45, and 60; check with the manufacturer.
The SK series ATC Chain uses the sprockets that are used for duplex power transmission roller chain. (The tooth range is limited.) HP series ATC Chain requires special sprockets.
Selection and Handling
- ATC Chains must be lubricated.
- When there is excessive tool overhang, use a tool guide to keep the chain straight.
- Change tools at the position shown in Figure 2.15.
- Positioning pins and grippers help to maintain accurate placement.
Figure 2.15 Positions for ATC Tool Changers