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钻床的补给单位钻床的补给单位补给钻头机械装置,钻杆, 而且在钻孔期间向面咬, 以及升起并且降低钻头杆。机械的补给单位与来自一个空气的电动机的驾驶很小而且能发展大的补给推力。然而, 他们也有一些缺点：补给速度低, 增加了对附加的操作的必需时间；装置在使用中复杂，不够可靠；而且电动机噪声大。空气的活塞补给单位设计简单，使用中靠, 而且补给柔性, 减少了刀尖的磨耗而且增加了钻孔的生产力。但是，他们也很大，因为依靠活塞的面积推动活塞把空气压缩到5-6 一个比较低的压力。然而，充足的定格补给推力却很少地被使用。为了提高钻床的操作性质，我们发明了一个新类型的空气活塞补给单位。它的主要特征是在补给气缸的气压比在空气输电干线中的大得多。这藉由压力转炉被达成系列中有一些活塞和气缸。图 1 表示一个补给的概要线图单位。工作零配件用活塞 9 和杆 3 包含补给气缸 1。压力转炉包含气缸 4、移动活塞 5 和一些带有挺杆 7的单一气缸 6 。每个挺杆的杆最后经过一个填函盖铸壁负担自由地与前述挺杆的冒口。空气被活塞阀 8 分配。系统的机械要素被导气管连接, 他含有背后阀 9 、和另外的一个停气阀 10。补给单位由水栓 11 控制。系统工作次序如下。来自输电干线的压缩空气经过进模口水栓 11 和阀 9, 抵达气缸 1 的左手方模穴。同时地空气获准进入气缸 4, 以及经过阀 10 和在活塞阀 8 中的环隙进入气缸 4 和 6 的右手模穴之内。 左手方模穴与活塞 2 有关,他创造了一个推力。而气缸 6 的左手方模穴总是在与大气沟通 。活塞 5 和挺杆 7移动到左边, 使气压变大。在气缸 4 的左手方模穴的空气被压缩比在输电干线中的压力大(这一个模穴中最大的压力仰赖气缸 6 的数目)。 高压的空气经过环隙 b 和延伸补给气缸 1,增加补给推力。在它的最左的位置, 活塞 5有一个口用导管c控制由气缸 4 的右手模穴进入的空气。空气进入活塞阀 8 的右手面貌, 在没有负载的左手方端防止空气由一个小孔 k 逃脱.(控制导管 d 现在被活塞 5 复盖)。活塞阀移动到左边。 当活塞阀在它的左方位中的时候，补给气缸 1 从压力转炉被分离。气缸 4 和 6 的右手模穴经由环隙 e 排气。来自输电干线的空气经过环隙一抵达气缸 4 的左手方模穴, 让活塞 5 和挺杆 7 移动到右边。当活塞 5 移动到最右边时，由导管 d 空气由导管 d 进入活塞阀 8 的左端. 这时导管c 被复盖，活塞阀的右端压力被释放。活塞阀移到右边, 继续循环直到补给气缸1的气压达到最大。转炉自动停止,当送料器的气压没有到达活塞 2时，转炉重新开始并增加补给气缸的工作模穴的容积。这样系统就在高的补给压力下操作。 如果提供给杆 3 的阻力很小, 在低的压力气缸中的活塞就会移动。然后空气的压力经由导管 f 到达活塞阀 10，防止空气从转炉中走开。另一方面，如果阻力过大，直接导致气压经过阀 9 不能够进行送料器的操作，那么在工作模穴的压力就会增加到输电干线压力，而且将会让阀 10 充份移动到右边，从而使空气进入转炉。直接补给和能切断压力转炉的活塞阀的出现,，使得钻床在没有转炉的的情况下更容易实现增加的压力只在一个深洞结束的时候被用。通过增加连续的可互相交换的挺杆气缸，可以建立补给单位达到必需的任何的最大补给推力。大体而言 , 拥有压力转炉的补给单位可能是水力的改为空气的。压力阶段的转炉因为低的空气消耗量可能在其他的空气装置中得到使用； 举例来说, 工作机的轮磨配件。A FEED UNIT FOR DRILLING MACHINESThe feed units of drilling machines feed the drill mechanism, drill rod, and bit towards the face during drilling, and also raise and lower the drill rod.Mechanical feed units with drive from a pneumatic motor 1 are small and can develop large feed thrusts. However, they have certain drawbacks: the feed velocity is low, which increases the time required for auxiliary operations; the apparatus is complicated and insufficiently reliable in use; and the pheumatic motor is noisy. Pneumatic piston feed units 2 are simple in design and reliable in use, and give elasticity of the feed, reducing wear on the bit and permitting an increase in the productivity of drilling. However, they are large, because the thrust developed depends on the area of the piston which is acted on by compressed air at a comparatively low pressure of 5-6 kg/cm . Nevertheless, the full rated feed thrust is quite rarely used (for example, in the last few meters of a deep borehole).With the aim of improving the operational qualities of drilling machines, we have developed a new type of pneumatic piston feed unit. Its essential feature is that the air pressure in the feed cylinder can be several times greater than that in the air mains. This is achieved by means of a pressure converter consisting of several pistons and cylinders in series.Figure 1 shows a schematic diagram of the feed unit. The working parts comprise feed cylinder 1 with piston 9 and rod 3. The pressure converter consists of cylinder 4 with freely moving piston 5 and several single cylinders 6 with tappets 7. The rod of each tappet passes through a gland in the end wall and freely bears on the head of the preceding tappet. Air is distributed by piston valve 8. The elements of the system are connected by air ducts, one of which contains back valve 9, and another cut-off valve 10. The feed unit is controlled by means of tap 11.The system works as follows. Compressed air from the mains passes through inlet tap 11 and valve 9, and arrives in the left-hand cavity of cylinder 1, where it bears on piston 2, creating a thrust. Simultaneously air passes into cylinder 4, and also through valve 10 and annular space a in piston valve 8 into the right-hand cavities of cylinders 4 and 6. The left-hand cavities of cylinders 6 are always in communication with the atmosphere. Piston 5 and tappet 7 move to the left, and the forces created by the air pressures on each of them are added together. The air in the left-hand cavity of cylinder 4 is compressed to a pressure greater than that in the mains (the maximum pressure in this cavity depends on the number of cylinders 6). The high-pressure air passes through annular space b and reaches feed cylinder 1, increasing the feed thrust.Approaching its extreme leftward position, piston 5 opens a port to control duct c into which air at mains pressure comes from the right-hand cavity of cylinder 4. The air bears on the right-hand face of piston valve 8, the left-hand end of which is at this time freed from load owing to escape of air via a small hole k (the control duct d is now covered by piston 5). The piston valve moves to the left.When the piston valve is in its leftward position, feed cylinder 1 is disconnected from the pressure converter. The right-hand cavities of cylinders 4 and 6 are connected to the exhaust via annular space e. Air from the mains passes through annular space a and arrives in the left-hand cavity of cylinder 4, causing piston 5 and tappet 7 to move to the right. When piston 5 reaches its extreme right-hand position, it opens duct d and mains-pressure air enters the left-hand end of piston valve 8. At this time duet c is covered and the right-hand end of the piston valve is released from pressure. The piston valve moves to the right, and then the cycle is repeated until the pressure in feed cylinder 1 reaches its maximum value. The operation of the converter is then automatically stopped, and is recommenced as the air pressure in the feeder fails owing to forward movement of piston 2 and increase in the volume of the working cavity of the feed cylinder. Thus the system operates at high feed pressures.If the resistance offered to rod 3 is small, the piston moves in the cylinder at low pressures. Then the pressure of the air passing via duet f to piston valve 10 cannot overcome the force of the spring and air from the mains is cut off from the converter. On the other hand, if the resistance offered to the rod increases so much that direct feed via valve 9 cannot effect operation of the feeder, then the pressure in the working cavity increases to mains pressure and will be sufficient to move valve 10 to the right, so that it admits air to the converter.The presence of direct feed (via the back valve) and of the piston valve, which cuts off the pressure converter, permits drilling to be effected in most eases without the converter; increased pressure is used only at the end of a deep borehole. By adding successive interchangeable cylinders with tappets, it is possible to build up the feed unit to any maximum feed thrust required by the drilling conditions.In principle, the feed unit with pressure converter can be hydraulic instead of pneumatic. The pressure step up converter might find uses in other pneumatic devices with low air consumption; for example, attachments to machine tools.
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