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LinearChain Info

Introduction

Framo Push-Pull Chains are made from precision manufactured chain links of a special design which enables the chain to push as well as pull heavy loads.
The chain links have a special profile with interlocking fingers at one end enabling the chain to roll or fold-up in one direction only. When unfolded, the fingers latch together to form a rigid thrust device. The close tolerance manufacture of the chain links and other components means that both push and pull linear motion with low backlash and high repeatability is achieved.
When retracted the Push-Pull Chain folds up to occupy minimum space in relation to the required stroke. This feature is especially beneficial where long stroke push-pull movement is required; stroke lengths of 5 meters or more are not uncommon.
The Framo Push-Pull Chain is an alternative to standard solutions using rack and pinion, screw-jacks, hydraulic and pneumatic cylinders or hoist mechanisms and can often present a unique solution where space is severely limited.
The Push-Pull Chain can be selected for thrust loads from a few kilograms to several tonnes - even where longer strokes are required. A Push-Pull Chain drive system can be configured with standard Chain Guide Rails where there is a danger of bending movement occuring. It is also possible to configure systems using several chains in a parallel drive geometry where higher thrust loads are required.

LinearChain Drive Systems

The chain drive system comprises a special housing with internal chain guides, spocket drive wheel and a keywayed drive shaft. This can be connected to a standard gear motor. Alternatively a Framo COMPACTA slip-on Rotary Actuator). -a gear motor with integral multi-turn limit switches and optional reversing contactors or potentiometer can often be used (see separate catalogue). To prevent the Push-Chain from folding during the linear thrust motion a special front end link is provided. This ensures that the force-line is off-center to the chain pins creating a bending moment which forces the chain fingers to lock tightly. The Push-Chain can be used for reciprocating push and pull movement, horizontally or vertically. Where possible chain guide rails should be used to support and guide the chain.

The Guide Rail is unnecessary when:
- The Push-Chain runs across a flat surface (eg. steel plate)
- The linear travel (stroke) is within prescribed limits
- There is no danger of radial loads occurring along the thrust axis

Chain Types and Performance Criteria

The selection of the correct chain size and type will depend on the application, the required performance and operating criteria.
The following information is required:

- Thrust force
- Working stroke
- Linear speed
- Operating frequency
- Temperature

Framo Push-Chains are manufactured with a standard pitch of 25 mm, 40 mm and 60 mm (pitch is the distance between the pivot pins).

Material Used

Framo Push-Pull Chains are manufactured from treated alloy steels. The chain can withstand temperatures of up to 180°C and for short periods even higher temperatures.
For special cases where temperatures of up to 550°C may occur, the Push-Chain can be supplied in heat-resistant steels.

Typical Applications

Framo Push chains have been sucessfully used in the following sectors:
 
Industrial furnaces, cold sheet metal working, casting shops, rolling mills, machine tools, automotive manufacturing, warehousing, internal works transport systems, chemical industry, nuclear industry.

Safety Regulations and Permitted Use

Framo Push-Pull Chains should not be used for applications involving the movement of loads which could endanger working personnel as a result of operation or system failure. Use of the Push-Pull Chain for personnel transport systems is not permitted without prior written approval.
 
We refer users to the applicable regulations and recommended practices regarding the provision of guard rails or covers to all moving parts of machines. Furthermore overhead hoist mechanisms for heavy loads using the Push-Pull Chain are not approved.

Example Application

Battery furnace.
The Push-Pull Chain is used to move a platform in and out of a furnace for heat treatment of the product. The chosen Push-Pull Chain geometry was as shown in Diagram 5 below. The rear end of the chain is fixed to the drive housing and folds above the drive assembly without further support. A simple cover was produced to guard the chain.

Examples of Push-Pull Chain Storage Geometry

Design Calculations

Type 25 Type 40 Type 60 Pitch of the chain p[mm] 25 40 60 Stroke per drive shaft revolution [mm] 200 240 360 Drive speed n[min-1] at given linear speed v [mm/s] n = v x 60 8 x p n = v x 60 6 x p n = v x 60 6 x p Required torque Mt [Nm] at drive shaft for thrust force F [N] Mt = F x d    Pitch 25 mm; d = 65,3 Pitch 40 mm; d = 80 2 x x 1000 Pitch 60 mm; d = 120 ( = ca. 0,8 without storage ) ( = ca. 0,65 with storage ) Required power P [kW] at drive shaft for torque Mt [Nm] P = Mt x n 9550

Loading Characteristics

The two load point holes in the front end-link are provided to ensure that a thrust force reaction exerts a radial turning movement around the chain pins.
The result is that the chain finger is under compression, the chain is rigid and cannot fold. For this reason fixing the load point to only one of the holes is not permitted.

Thrust Force in Relation to Stroke

Important:
These diagrams are based on the operating criteria shown below and adherence to operating instructions. For operation outside these parameters please contact our sales office.

- Linear speed: 150 mm/s
- Frequency: 10 Anläufe / h
- Temperature: 200 °C
- Non-corrosive atmosphere

Push-Pull Chain without guide rail, load point guided

Installation Tolerances

The drive housing should be installed in accordance with the adjustment tolerances given below to achieve a maximum thrust and a minimum rate of wear.
The center line of the Push-Pull Chain middle roller in relation to the reaction guide plates should be especially noted.

Angular tolerances Reaction plate - guide plate Reactions plate - sliding surface Pitch 25 40 60 H 1 +/- 0,1 mm 9 18 24 H 2 +/- 0,1 mm 0 2 3 H 3 +/- 0,1 mm 40,5 49,2 75,2 H 4 +/- 0,1 mm 24,8 30,82 44,7 H 5 +/- 0,1 mm 32,7 40 60

Lubrication and Maintenance

As a result of the high grade of materials used and the robust construction of the Push-Chain, the only maintenance required is a regular lubrication of the surfaces. The lubrication intervals will depend upon the working criteria and in particular the operating frequency and working temperature.
It is recommended that all moving parts be inspected regularly for signs of wear.

Lubricating oil can be applied evenly across the whole length of the chain using a brush. Standard synthetic lubricating oils such as Mobilith SHC PM from Mobil or similar can be used in most applications. For high duty rating applications we recommend using automatic brush lubricators.

Calculation of Chain Length and Number of Chain Links

Calculation of chains without fixed end link 90° - drive housing 180° - drive housing { C = Usable stroke Total chain length L = C + M + (5xP) M = Basic position P = Pitch Calculation of chains with fixed end link 90° - drive housing 90° - drive housing mit 180° - return Total chain length L = C + M + (10xP) Total chain length L = C + M + (15xP)

Information About Housing

General

A specially designed drive housing is needed to convert the gearmotor torque to a linear thrust. The drive housing contains a guide plate and a reaction plate which keep the chain engaged with the sprocket, converting the sprocket's rotary force into linear force as the Push Chain leaves the drive housing. The plates can be configured for either a 90° or a 180° turn.
 
For larger thrust forces a duplex chain is used with a double sprocket wheel.
 
The drive shaft can be driven directly by a slip-on hollow-shaft motor such as Morat's Compacta series. Standard solid-shaft motors can be connected using a flexible coupling.

Material and Maintenance

The drive housing is manufactured from cast aluminum or cast steel. A special version can be manufactured from stainless steel.
Internal parts are maintenance-free. The bearings are lubricated for life.

Installation and Drive Shafts

JThe drive housing is provided with a right-angle mounting bracket on each side. These can be positioned at any of 4 locations (90° offset).

Housing Weights