WO2000056499A1

WO2000056499A1 - Vacuum chip removal system

Info

Publication number: WO2000056499A1
Application number: PCT/US2000/006068
Authority: WO
Inventors: Cameron F. Anders; Peter F. Woerner
Original assignee: Gleason Works
Current assignee: Gleason Works
Priority date: 1999-03-23
Filing date: 2000-03-08
Publication date: 2000-09-28
Anticipated expiration: 2001-09-23
Also published as: AU3731300A

Abstract

A vacuum chip removal apparatus (2) wherein a damper valve (12) is included in combination with chip hopper doors (22) whereby the damper valve operates to close off air flow through the apparatus, thus eliminating a vacuum, prior to chip hopper doors being opened to discharge chips from the apparatus. With vacuum eliminated, outside air will not rush in through the hopper doors to disrupt chips in the hopper (8) and potentially harm components of the vacuum apparatus. Once chips are emptied from the hopper (8), the hopper doors (22) are closed and the damper (12) is then opened to restore vacuum to the entire chip removal apparatus (2).

Description

VACUUM CHIP REMOVAL SYSTEM

This application claims the benefit of U.S. Provisional Application No. 60/125,574 filed March 23, 1999.

Field of the Invention

The present invention relates to an apparatus for conveying chips away from the machining area of a machine tool, such as a machine for producing bevel and hypoid gears, by the application of a vacuum in which the apparatus includes means to discharge collected chips by controlling the vacuum.

Background of the Invention

Recently, dry machining processes such as dry hobbing of cylindrical gears and dry cutting of bevel gears have drawn attention as an alternative to processes utilizing coolant (wet machining processes). See, for example, Phillips, "New Innovations in Hobbing - Part II", Gear Technology,

November/December 1994, pp. 26-30, and, Stadtfeld, "Gleason POWER- DRY-CUTTING™ of Bevel and Hypoid Gears", The Gleason Works, Rochester, New York, May 1997. It may be seen that dry machining has the potential to overcome many serious and costly drawbacks associated with the use of a liquid coolant, such as the purchase expense, the disposal costs, the environmental hazards due to coolant mist and coolant oil smoke, as well as additional machine expense for mist/smoke collectors, pumps, hoses, filters, chillers, and chip separators. Also, dry chips are normally more valuable as a recyclable material than chips which are residually wetted by a process fluid. Parts cut without coolant do not need washing, prior to further processing such as heat treatment.

However, the heat generated in dry machining processes is a contributor to tool wear and it also may have detrimental effects on the machine itself, causing differential growth of components such as spindles, bearings, or the machine frame. Much of the process heat in dry machining is removed by the chips that must be removed from the machine as quickly as possible and in a manner by which they do not contact the machine frame for any extended period of time.

One way to remove dry chips is to permit the hot chips to slide by gravity toward a chip conveyor built into the base of a hobbing machine.

Such a chip removal system is shown in Ophey, "Gear Hobbing Without Coolant", Gear Technology, November/December 1994, pp. 20-24.

Another method of removing chips from a machine tool capable of wet and dry machining is known from commonly assigned U.S. Patent No.

5,586,848 to Suwijn wherein the chips are discharged into the machine base where a reversible transfer mechanism carries them to respective wet or dry outlets.

Still other manners in which to remove chips from the machining interface and out of a machine is disclosed in commonly assigned U.S. Patent No. 5,951 ,219 to Stadtfeld et al. and copending U.S. Patent Application No. 60/116,158 to Anders. In each disclosure, a generally circular-shaped shroud encloses an engaged tool and workpiece such that chips emanating from the tool-workpiece interface are confined to the shroud and are directed into an outlet where they are conveyed away from the machine tool.

One method for conveying chips away from a chip-confining shroud apparatus, such as that discussed above, is through the use of a vacuum. The use of vacuum as a means to assist flow of a mass is, per se, well known. For example, U.S. Patents Nos. 3,729,903 to Espeel et al.; 3,798,878 to Pausch; and 4,077,781 to Sundstrom illustrate particle collection systems of the type in which air entrained particles enter a chamber where, through the use of an expanding flow path and filters, the air and particles lose velocity thus separating the particles from the air, resulting in the particles falling to the bottom of the chamber. Periodically, the particles are transferred, via a lower door for example, into a receptacle.

However, a problem that exists in particle separation means of this type is that opening the lower door while air is moving through the chamber (i.e. while vacuum is being applied to the machine tool chip-confining shroud), causes significant disruption of the chips lying in the bottom of the chamber, since air will be drawn in through the lower door. The problem may be avoided by stopping the motor driving the fan that creates the vacuum, however, this is a time consuming process as one must wait for the fan to stop. After the particles are emptied through the bottom door, additional time must also be expended while the motor and fan reach operating speeds again. Furthermore, during this discharging process, operation of the machine tool must also be suspended.

It is known to utilize a rotary airlock at the bottom of particle chambers but such airlocks include sealing means, such as rubber strips, to close the gap that exists between the vanes of the airlock and the surface of the chamber. Rotation of the airlock results in continuous contact between the sealing means and the chamber resulting in wear. In addition, as the airlock rotates, particles can become lodged between, and cause abrasion of, the sealing means and the chamber wall. Thus, considerable maintenance is required when utilizing rotary airlocks. Furthermore, with rotary airlocks, it is difficult to provide adequate safety guarding while maintaining good chip flow.

It is an object of the present invention to provide a system to remove metal chips from a machine tool by the application of vacuum in which the metal chips are separated from air in the vacuum device and can be removed from the vacuum device without causing wear to components, disruption of the chips in the device, or suspension of the operation of the machine tool.

Summary of the Invention

The present invention is directed to a vacuum chip removal apparatus wherein a damper valve is included in combination with chip hopper doors whereby the damper valve operates to close off airflow through the apparatus, thus eliminating the vacuum. Following the closing of the damper valve, the chip hopper doors are opened to discharge chips from the apparatus. With the vacuum eliminated, outside air will not rush in through the hopper doors to disrupt chips in the hopper and potentially harm components of the vacuum apparatus. Once chips are emptied from the hopper, the hopper doors are closed and the damper is then opened to restore vacuum to the entire chip removal apparatus. Brief Description of the Drawings

Figure 1 illustrates a cross-section of the inventive vacuum chip removal system when viewed from a side.

Figure 2 illustrates a cross-section of the inventive vacuum chip removal system when viewed from an end.

Detailed Description of the Preferred Embodiment

The present invention will be discussed in detail by referring to preferred embodiments and the accompanying drawings. In the drawing figures, like reference numbers refer to similar components.

The present invention may be in communication with any machine that produces dry chips as a result of a machining process. As discussed previously, the present invention is contemplated as being in communication with the outlet of a chip-confining shroud of a bevel and hypoid gear manufacturing machine. However, it will become apparent that the present invention may be placed in communication with the source of dry chips emanating from any machine tool.

Figure 1 illustrates a cross-section of the inventive vacuum chip removal apparatus 2 when viewed from the side. The vacuum apparatus 2 includes an inlet 4 (for example, six inches in diameter) where chip-entrained air from a machine tool enters the apparatus 2. Upon passing through inlet 4, the air and chips encounter a enlarged vacuum path region or chamber 6 having an area greater, preferably on the order of ten times, than the area of the inlet 4. The increase in area decreases the velocity of the air stream as well as the suspension of the incoming chips. The reduced-velocity chips separate from the air stream and fall into the chip hopper 8. The air stream then continues through the filters 10, (preferably four in number, with each filter having a filter area of about 226 ft.²), which trap any fine metallic particles still suspended in the stream. The air stream then continues past open damper 12 (dashed lines), through the fan 14, along a tortuous path 16 around sound dampening material (not shown) which helps eliminate noise made by fan 14 and motor 18 (3 horsepower, for example), and exits the vacuum apparatus at 20.

After a predetermined number of cutting cycles of the machine tool, air path damper 12 is closed (solid line) across the air stream, either manually or preferably power actuated by means such as air pressure, hydraulics or electricity. From the standpoint of cost, an air cylinder (not shown) is preferred. The power actuated means may be manually activated or, preferably, may be controlled by a computer. Since the fan 14 has no air to move, it will freewheel and the current will drop. The pressure in the rest of the apparatus 2 will rise to ambient. After a short delay, closed hopper doors

22 (solid lines) may now be opened (dashed lines) to allow accumulated chips in the hopper 8 to fall into a movable hopper 24 below the doors 22. The hopper doors 22 are then closed, damper 12 is reopened, and vacuum conditions will resume in the apparatus 2.

As with control of damper 12, control of hopper doors 22 may be manual but are preferably power actuated by means such as air pressure, hydraulics or electricity. Again, from the standpoint of cost, an air cylinder is a preferable actuator. The power actuated means may be manually activated or, preferably, may be controlled by a computer. Most preferably, opening and closing control of both the damper 12 and hopper doors 22 are computer controlled such that their respective movements occur sequentially. Control of the damper 12 and doors 22 may originate from the machine tool computer control and may be programmed to discharge accumulated chips after a predetermined number of workpieces have been machined. Discharging of chips can occur during unloading and loading of workpieces so that little or no machining time is lost due to discharging of chips.

To keep filters 10 from becoming clogged with fine particles from the air stream, at a predetermined interval, filter cleaning means 26 is triggered manually, or preferably by the machine computer control, to backflow filters 12 with bursts of pressurized air. This blows the fine particles from the filter surface and into the hopper 24. While one pair of filters may be cleaned at a time, preferably, only one filter is cleaned at a time.

With no damper valve 12, and the apparatus 2 operating under vacuum (i.e. fan 14 running), the doors 22 to unload chips could not be opened without upsetting the chips and air stream. Opening the doors 22 with the vacuum still engaged, while being extremely difficult, would disrupt the air stream, causing the chips to "fly" erratically out of the hopper 8 instead of dropping into the movable hopper 24. Also, airborne pollutants could be pulled into the filters 10. However, with the inclusion of damper valve 12, the negative pressure (i.e. vacuum) can be instantly cut off to the chamber 6 with no harmful effects to the motor 18. The chamber pressure quickly equalizes and the doors 22 can be opened and the accumulated chips can be easily and quickly dropped into movable hopper 24. The effect on machine cycle time allows the vacuum chip removal system to easily keep time with the cutting process.

While the invention has been described with reference to preferred embodiments it is to be understood that the invention is not limited to the particulars thereof. The present invention is intended to include modifications which would be apparent to those skilled in the art to which the subject matter pertains without deviating from the spirit and scope of the appended claims.

Claims

CLAIMSWhat is claimed is:

1. A chip removal apparatus for removing chips entrained in a stream of air, said chip removal apparatus comprising: an inlet and an outlet, said inlet having an area and being in communication with said outlet via an air path through which said air stream may flow from said inlet to said outlet, fan means located along said air path to effect a flow of air from said inlet to said outlet thereby creating said air stream and a negative pressure along said air path upstream of said fan means, a separating chamber located along said air path upstream of said fan means, said separating chamber having an area greater than said inlet to effect a decrease in velocity of said air stream and any chips entrained therein whereby said chips separate from said air stream, a damper located along said air path between said fan means and said separating chamber, said damper being operable between an open position and a closed position.

2. The chip removal apparatus of claim 1 further comprising a chip hopper for collecting chips separated from said air stream, said chip hopper including an outlet for discharging chips from said chip removal apparatus, the chip hopper outlet being operable between an open position and a closed position.

3. The chip removal apparatus of claim 1 wherein with said damper in the closed position, said airflow is stopped and said negative pressure is increased to an ambient pressure along said air path upstream of said fan means whereby said chips may be removed from said chip removal apparatus without disruption of said chips due to a flow of air into or through said chip removal apparatus.

4. The chip removal apparatus of claim 2 wherein with said damper in the closed position, said airflow is thereby stopped and said negative pressure upstream of said fan means is thereby increased to an ambient pressure along said air path whereby chips in said hopper may be discharged from said chip removal apparatus by opening said chip hopper outlet without disruption of said chips in said hopper due to an inflow of air through said chip hopper outlet.

5. The chip removal apparatus of claim 5 wherein said chips are discharged from said chip hopper into an external movable chip hopper.

6. The chip removal apparatus of claim 1 further including filter means located along said air path between said separating chamber and said fan means.

7. The chip removal apparatus of claim 1 further including sound dampening means located along said air path between said fan means and said outlet.

8. A chip removal apparatus for removing chips entrained in a stream of air, said chip removal apparatus comprising: an inlet and an outlet, said inlet having an area and being in communication with said outlet via an air path through which said stream of air may flow from said inlet to said outlet, fan means located along said air path to effect a flow of air from said inlet to said outlet thereby creating said air stream and a negative pressure along said air path upstream of said fan means, a separating chamber located along said air path upstream of said fan means, said separating chamber having an area greater than said inlet to effect a decrease in velocity of said air stream and any chips entrained therein whereby said chips separate from said air stream, a chip hopper for collecting chips separated from said air stream, said chip hopper including an outlet for discharging chips from said chip removal apparatus, the chip hopper outlet being operable between an open position and a closed position, a damper located along said air path between said fan means and said separating chamber, said damper being operable between an open position and a closed position, wherein when said damper is in the closed position, said airflow is thereby stopped and said negative pressure upstream of said fan means is thereby increased to an ambient pressure along said air path such that chips in said hopper may be discharged from said chip removal apparatus by opening said chip hopper outlet without an inrush of outside air entering into said chip hopper through said chip hopper outlet to cause disruption to said chips in said hopper.

9. A method of removing chips entrained in a stream of air in a chip removal apparatus and discharging said chips from said apparatus, said method comprising: providing a chip removal apparatus comprising an inlet, separating chamber, damper and an outlet, said inlet being in communication with said outlet via an air path through which a stream of air may flow from said inlet to said outlet, the air flow along said path effecting a negative pressure in said air path, passing an air flow containing entrained chips through said inlet and along said air path to the separating chamber wherein said chips separate from said airflow, said chips entering a chip hopper having a discharge outlet and said air flow continuing along said air path to said outlet, closing said damper to prevent the flow of air along said air path and to effect a rise in pressure to ambient in said air path, opening said chip hopper discharge outlet such that chips in the hopper may be discharged from said chip removal apparatus without an inrush of outside air entering into said chip hopper through said chip hopper outlet to thereby cause disruption to said chips in said chip hopper.