I’m often contacted by engineers asking for assistance with replacing, retrofitting or designing belts for curved conveyors – known as powerturn installations – which are used to change the direction of a conveyor by anything from 30° to 180°.
These complex installations are found in a wide variety of industries, from food to materials handling, distribution and warehousing, and each requires customized fitting and design, as well as highly accurate manufacture.
In simple terms, a curved belt consists of a number of sections joined to form a cone-shaped belt, which is then tensioned around tail pulleys. These pulleys can be conical or cylindrical, depending on the application.
How do you select the best design for a powerturn installation? It starts by being aware of the basic mechanics involved.
1.皮带指导至关重要
Due to the nature of the curved belt, there are strong transverse forces that pull the belts inwards towards the center point of the curve. These forces must be offset by using guidance at the outer edge of the belt, with either a drive chain to do the work, or belt tension using rollers or profiles. The three main types of guidance used at the outer belt edge are:
- 驱动链
- Pairs of roller
- 个人资料
· Guidance using a drive chain
In our experience, guidance using a drive chain is simple, effective and optimal in situations where relatively small transfers are needed (for example in the food industry). All the tension is taken on the outer edge of the belt by the chain, with the belt acting as a sleeve.
链条在安装的外边缘运行，皮带通过弹簧，金属支架或最常通过塑料环连接到链条上，因此既可以驱动并保持在正确的位置。由于驱动器是通过链条进行的，因此皮带不会像有驾驶滚轮那样驾驶摩擦，这意味着跑步紧张局势很低，从而优化了皮带使用寿命。
· Guidance using pairs of rollers
This solution uses pairs of rollers mounted on the outer belt edge that run on curved rails to offset the transverse forces. Very high-precision belt and frame fabrication are a must in this case, as well as highly accurate mounting hole placement on the outer edge of the belt. As the belt in this situation is driven by a drive roller, the belt service life will be affected by the higher running tensions. The belt set up and tracking control also need careful monitoring to prevent the belt becoming damaged.
·使用皮带边缘轮廓的指导
在这种情况下，将挤出的轮廓粘合或经常缝在皮带的外边缘上，该外边缘通过在角度滚子下运行的轮廓将其保持在适当的位置。该方法需要极度准确的指导剖面定位，并且由于塑料珠通过引导皮带轮的弯曲而导致的能量损失可能相对较高。但是，结果是一条皮带可以相对易于更改或更换，因为滚筒被重新定位在轮廓上后，设置最小。
根据我们的经验，对于使用较重的皮带的配电仓库和应用，后两种指导层在该皮带上进行工作，因此更合适，因为可以选择更重，更耐用的皮带。
2.皮带的选择现在比您想象的要宽
与传统的皮带（纵向灵活但侧面刚性）不同，弯曲装置上使用的皮带需要在各个方向上都具有柔韧性，因为它们在各个方向都受到弯曲应力。
一些工程师认为，实现这一目标的唯一方法是选择带有car体的腰带，由翘曲（长度）和纬线（宽度）方向组成，以使皮带在所有方向上都很灵活。但是，这并不总是必要的。通过仔细切割和连接段，几乎所有皮带材料都可以制造用于Powerturn安装，从而确保了更广泛的皮带选项，包括蓝色皮带和TPO-或TPU涂层皮带，以供食品应用，并需要清洁要求。
For example, if the belt required is a single ply belt, using a relatively big pulley diameter (15 mm or 16 mm), it is even possible to use a belt that is made to be laterally rigid, as it will still be flexible enough across the width. We proved this recently with a customer in the UK using a monofilament belt.
There are limitations, however. Monofilament belts cannot be used in applications with a static nosebar at infeed or outfeed, since friction will drive the mono filaments out of the belt.
3.创新的解决方案可以解决关节应变
在最近的一个案例中，我们被要求帮助您的皮带，该皮带因在设置外喂养滚轮和链条链轮之间的空隙区域的关节应变而失败。在这种情况下，我们设计了一个增强区域，以阻止皮带接头失败。
Wherever possible it is good to cut down on the number of joints used. Not only do multiple joints and panels cost time and money, they can also lead to buckling due natural variations that occur during the fabrication process.
4. Accuracy is essential
Belt fabrication for powerturn installations must be extremely precise during cutting and joining. Whereas in the past curved belts were cut by hand, new CAD technology provides greater accuracy and precision. It has to be said, however, that it is generally not the fabrication process that causes problems, but inaccurate data and measurements.
5. PowerTurn安装的大小没有限制
可以将弯曲的皮带从最大3 m宽的皮带材料切割。但是较大的PowerTurn安装也是可能的。使用面板，我们制作了一个180°POWERTURN，皮带宽度为1900 mm，外部半径约为6 m，总圆周约为37.5 m。
6. 100% product placement accuracy is impossible on a powerturn
我经常被问到是否有可能通过Powerturn保持精确的产品放置。不幸的是，答案是：不是当前。一系列巧克力棒永远不会像进料一样在外喂养处完全相同。机械师只是不允许这样做。这是简单的产品移动，而不是滑倒，这是由于如何设计Powerturn以及零度的真实基准点实际位于返回和输送皮带路径之间的事实。
您对PowerTurn安装有任何疑问吗？
正确获得PowerTurn安装取决于专业知识和经验以及合适的合作伙伴。如果您想了解Habasit如何为您的PowerTurn安装需求提供正确的腰带，请contact me。
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