How to Choose a Union? Proper selection of a Rotating Union requires detailed
如何正确选择旋转接头

正确选用机床旋接器的四个步骤

1.机床需要供应单一介质(例如,冷却液)还是多种介质( 例如冷却液、气体 及液压油组合 ) ?
2.旋接器传输的是何种介质?
3.最高压力是多少
4.主轴最高转数是多少?

选用何种杜博林密封技术?

杜博林提供5种不同密封技术,为不同机床提供最佳解决方案。只有杜博林能够为机床设计人员提供如此大的选择空间。

1、闭合式密封: 如同其名,无论有无冷却液压力密封始终是保持封闭的。因此一般来说不需要排放管。但所有的旋接器运转时,在密封之间都有一薄层介质。随着时间的推移,会有几乎不可察觉的少量介质流过密封面。因此必须采取有效的排放措施。较其它设计,冷却液中杂质对闭合式密封影响较小。然而,如果没有冷却液存在,闭合式密封旋接器不可长时间运转。

2、控制泄漏式密封: 与闭合式密封相反,控制泄漏式密封即使在有压力时,密封面之间也有一个较小的间隙。因此,控制泄漏式接头非常出色地应用在干气的高速旋转场合。一般来说,控制泄漏式旋接器不适合于冷却液应用。

3、脱开密封: 这种密封只有在有压力时才闭合。当压力消失后,密封面会脱开一段少许距离。这样就排除了密封会在无液运转时产生摩擦与磨损。因此可实现不受限制地高速“干运转”。在机加工内冷(TSC)时有时无的情况下应当考虑采用脱开式设计。因为在换刀时密封是分离的,无冷却液压力,残留在供给软管和主轴内的冷却液会通过密封间隙排放 保参主掉。因此,脱开M旋接器一般要求安装位置向下的排放管以便可以直接排放残留冷却液到废液槽。同时应注意到,在以压力干气为介质时,脱开旋接器不能长时间应用。

4、自动感应密封: 杜博林最新开发系列,此项技术融合了脱开M与控制泄漏式密封的设计优点。同脱开M设计一样,自动感应M密封也是在有冷却液压力时闭合,当没有冷却液压力时“脱开”,从而不受限制地干运转。如同控制泄漏式设计,自动感应密封通过在密封面之间产生一个很微小的间隙来处理干气。在处理冷却液、MQL及干气时,自动感应旋接器通过感应介质性质自动改变相应的密封方式。同脱开
除非另密封一样,也要求安装排放管路。

5、全介质式密封: 采用该技术后,机床设计人员能够完全控制密封的开、合。设计人员可以通过控制施加到旋接器各连接上的压力使密封在必要时分离(例如,输送承压干气)或在适当时闭合(例如,输送冷却液或油雾)。一般也要求安装排放管路。

选择轴承支撑式还是无轴承式？

机床所应用的旋接器分为轴承支撑式与无轴承式。对于机床设计人员来说,每种形式都有其优缺点。

轴承支撑旋接器因为采用一体化设计,其优点是易于安装和更换。杜博林旋接器采用2种不同的安装形式。一是转子安装式,以螺纹形式将转子与加工中心连接。二是壳体安装式,旋接器插入主轴端部精确加工的沉孔内。这两种方式的第二个优点是,任何泄漏都能通过壳体连接导入排放管路。第三个优点是,采用转子安装式有轴承旋接器几乎可以全部吸收主轴上因冷却液压力引起的轴向力(推力载荷)。然而,对于壳体安装和无轴承旋接器来说,冷却液压力却可在主轴上产生一定的推力载荷。无轴承旋接器对于机床设计人员来说有若干优点。首先,因为取消了轴承而降低了成本,而同时却能提高最高转速。其次,仅有很小的转子直接连接到主轴,因此旋接器壳体不可能成为振动源。第三,因为没有轴承,旋接器免受侧向载荷,例如,因冷却液供给软管张力而产生的侧向载荷。第四,无轴承接头可以做得很小,非常适合于密集多主轴应用。但无轴承接头必须分两部分安装,即转子和带有非旋转部件的小壳体,并连接到冷却液供给源。所以,在安装过程中,精研密封面暴露在外,必须特别小心处理。

Proper selection of a Rotating Union requires detailed:

Equipment fitting information
Operating parameters

Equipment Fitting Information:

Union Size & Thread Spec:
螺纹形式和连接尺寸

This is the nominal size of the union and the thread or attachment specification of the Rotating Union for installation on to the machine roll.
Example: 1” NPT RH, 5/8-18 UNF LH, 2” BSP LH, etc


Number of Passages
通道数

Union may have 1, 2, 3, 4 or more passages. If there are 2 passages, the Union may be Duoflow where the same media enters and exits through the same union. Alternatively, 2 passages could transmit the same media at two different pressures or 2 separate media could be transmitted at 2 different pressures.


Supply Pipe:
供给管类型

Most Duoflow unions allow fluid to flow in and out through the same union. This type of closed circuit flow requires a supply pipe to either deliver or serve as a channel for the media to return. Supply/Return pipes are supported at one end by the union and the other end might simply be cantilevered into the roll or may be supported by some sort of a bushing or spider. Supply/Return Pipes, depending on the roll configuration of the machine, may by stationary or rotating.

Operating Parameters:

Media
介质

What is the media being transmitted? It may be water, air, hydraulic fluid, coolant, steam, hot oil, etc

Pressure
工作压力

An application may require transmittal of a single media at a single pressure. Sometimes, the pressure may vary. Always consider the max operating pressure as the operating pressure. Also, if the application calls for multi passages, it is important to know the max pressure of each media and the channel (inner or outer) being considered for flow of respective media.

Temperature
温度

For most water applications, the media temperature might be ambient. However, it is important to know the temperature of the media. Rotating Unions comprise of various internal components with their individual temperature limits. Rotating Unions with standard deep groove ball bearings have a temperature limit of 250F/120C. Heat stabilized bearings with special hi-temp grease extend the temperature to 320F/160C. For higher temperatures yet, bushing type bearings are utilized since they are self- lubricating and typically have much higher temperature limits.


Speed & direction of Rotation
转速和旋转方向

This is a critical Operating Parameter. Higher speeds machine require better alignment of Rotating Union to the machine roll. NPT threads are quite suitable for slower machine speeds. Beyond 1500 rpm, NPT threads, due to the taper, do not provide accurate alignment of the Rotating Union relative to the machine roll. In these instances, machine thread is recommended. For higher speeds yet, such as machine tool applications, the Rotor of the Rotating Union features a ground cylindrical pilot surface for accurate installation and alignment.

Direction of Rotation is an equally critical Parameter. High speed machine tool spindles accelerate at a very rapid speed. The thread direction must always be opposite to the direction of rotation of the spindle. For slow speed applications, this may not be so critical. However, in order to fit any rotating union, the thread direction must be consistent with the direction of threads of the roll.