US2320747A - Cylinder honing - Google Patents

Description

June 1943- v. w. PETERSON EI'AL 2,320,747

CYLINDER HONING Filed Dec. 29, 1938 2 Sheets-Sheet l W o 6 m June 1943- v. w. PETERSON El'AL 2,320,747

CYLINDER HONING Filed D ec. 29, 1938 2 Sheets-Sheet 2 Patented June 1, 1943 CYLINDER. HONING victor W. Peterson and Frank J. Daley, Chicago,

Ill., assignors to Hannifin Manufacturing Company, Chicago, 11]., a corporation of Illinois Application December 29, 1938, Serial No. 248,213

Claims.

This invention relates to honing of cylinders and the like, and among other objects aims to provide an improved and simplified apparatus for forming straight and true cylinder bores.

The nature of the invention may be readily understood by reference to one illustrative apparatus and its method of use shown and described in the drawings and accompanying specification,

In said drawings:

Fig. 1 is a longitudinal section (taken on the broken plane Il of Fig. 2) of a honing tool in position inside a cylinder to be honed; and

Fig. 2 is a transverse section taken on the broken plane 22 of Fig. 1.

As applied to cylinders and the like, honing may be employed to form not only a smooth or polished cylindrical bore but one accurate to a fraction of a thousandth of an inch both in diameter and straightness. The honing operation is characterized by the simultaneous reciprocation and rotation of a hone through the cylinder bore. For best results, there should be a definite relation between the rates of rotation and reciprocation of the hone. Preferably these rates should be such that the helical marks or scratches formed by the hone on its forward stroke should cross those formed on the return stroke at angles between 40 and 60".

In general, the honing tool comprises a series of elongated stones, preferably arranged parallel to the axis of the bore and radially pressed outwardly against the cylinder wall. It is important that the pressure of the stones against the cylinder wall be uniform and constant despite the wearing away of the cutting stones and removal of metal. Under these conditions, high and low spots in the cylinder will be removed and the bore made straight and true.

Originally honing was employed principally as a finishing operation or to remove only very slight irregularities or out-of-round conditions. Substantial high spots" resulted in excessive stone breakage. Other incidents of prior practice were excessive time required for the honing operation and the necessity for frequent adjustment of the hone. All of these diificulties were magnified in honing long cylinders.

Since the rate at which metal is removed depends upon the rate at which the cutting stones are broken down (to expose fresh cutting points), the problem of maintaining adequate uniform and constant. pressure of the stones against the metal and avoidance of breakage of the stones on high spots is a substantial one.

In the illustrative hone, adequate uniform and constant pressure is maintained despite the wearing of the stones without the necessity of frequent adjustment of the tool and without danger of breakage of the stones. This result is obtained by pressing the stones outwardly by pneumatic pressure applied, in this instance, by a flexible tube l 0, extending longitudinally inside the honing tool II and inflated sufiiciently to apply the desired stone pressure.

As here shown, the honing stones l2 are rigidly mounted on a plurality of carriers in the form of plungers l3 slidable in outwardly directed bores M in the cylindrical body l5 of the tool. The bores need not be radial. If they be at an angle to the radius,'the effective width of the cutting face of the stones is increased somewhat. Preferablythe plungers project into the central bore iii in which the inflated tube lies, sufficiently to bring the plunger into efiectivc contact with the inflated tube and to provide a substantial range of radial movement of the plungers (without obliging the flexible tube to expand into the bores M) to adapt the tool to a substantial range of bore diameters. The range of tool diameters may be increased if the plungers be not diametrically opposite but are staggered so that for small bores their ends may project inwardly beyond the axis of the tool. The same tool may be used on still larger bore diameters simply by employing a longer set of carrier plungers I3. This is a very substantial advantage since it avoids the necessity of carrying a series of complete tools for varying bore diameters.

The number of sets of cutting stones may, of course, be varied. Six are here shown, each set mounted on three plungers. Preferably the bore M are lined with removable bushings I! to maintain a close sliding fit for the plungers and thereby prevent lateral play through wear.

The stones may be mounted on the carrier plungers in various ways. As here shown, the plungers support a rigid channel I8 seated in channel shaped recesses I9 in the enlarged extremities 20 of the plungers. Screws 2| hold the channel in place. The honing stones l2, in this case two for each set, are conventionally cemented or otherwise secured inside sheet metal channels 22 held by screws 23 inside the main channels l8. The character of the stones varies according to the character of the metal honed, the desired rate of cutting, the finish desired, etc.

The tube l0 may be made of a variety of materials but it is advantageous to employ an oil resisting synthetic rubber, such as chloroprene rubber. One rubber of this character is sold on the market under the trade-name neoprene." The ends 24 and 25 of the tube are supported against heads 26 and 21 closin the ends of the central bore l6 of the tool. The heads are removably attached to the body l by screws 28. The forward head 21 in this instance is formed integral with the operating shaft 29 by which the tool is rotated and reciprocated. In this connection it should be understood that the tool and its shaft are not rigidly connected to the driving means but have a floating" connection which enables the tool freely to follow the cylinder bore.

A passage 30 is provided in the shaft and head for the valve stem 3|. The valve stem may be an ordinary automobile tire tube valve stem connected to the tube in the conventional way and provided with a conventional valve. Other means may, of course, be used for maintaining and regulating the air pressure. The tube walls in this instance ar approximately 1% of an inch in thickness and are capable of carrying the pressure without danger of breakage even at the points 32 adjacent the ends of the plungers.

Various grades and types of stone, each suited to a particular metal or operation, are available on the market.

For removing metal at the maximum rate, it is desirable to operate with stone pressures as high as practicable, limited only by the ability of the chuck or other work ripping means to hold the cylinder without turning or without distorting the cylinder walls. It should be understood, however, that different pressures are generally required for different types of stone and difierent types of work. For low carbon steel, stone pressures of 50 to 80 pounds per square inch are satisfactory. In the illustrative apparatus (wherein the stones are 6" long and /2" wide and the carrier plungers are 1 in diameter), air pressure of 65 pounds per square inch would produce a stone pressure of about 40 pounds per square inch. Higher pressures are generally employed.

Unlike pressure produced by springs, the stone pressure in the illustrative apparatus is uniform and constant for all stones and radial positions of the plungers and regardless of stone wear. Nevertheless, the pressure may be easily changed. It may be made much higher than any spring of a size adapted to the tool could exert. The pressure can be easily released to remove and insert the tool.

The cutting stones are advantageously provided with means for moving the same inwardly when pressure is released to permit the easy withdrawal and insertion of the tool. The means here show-n are in the form of springs 33 whose ends are connected to clips 34 attached to the under faces of the channels l8.

In using the tool, the same is first inserted inside the bore to be honed and thereafter the tube is inflated to the desired pressures. The pressure on the stones is thus maintained uniform and constant throughout the operation regardless of the wearing of the stones or the radial position of the ends of the plungers. There are, therefore, no periods (due to reduction in pressure through stone wear as in other devices) at which the tool is not operating at maximum efficiency, that is, removing metal at the maximum rate. The ability of the stones to yield inwardly when striking a high spot makes it possible to use maximum pressures without danger of stone breakage, thereby reducing the high spots with maximum speed. Moreover, it is possible to regulate pressures exactly to those required for best results and exactly to duplicate conditions for similar kinds of work. Heretofore it has been impossible either to determine or regulate stone pressures or to duplicate conditions. In the present apparatus once the pressure has been set it is applied equally to all stones regardless of different rates of wear; it is uniform throughout the entire length of the cylinder regardless of wear and remains constant throughout the entire operation.

The light weight of the illustrative hone (about one-third that of the tools heretofore employed) is of substantial advantage in horizontal honing operations, such as honing long cylinders. It is unnecessary to turn the cylinder repeatedly to compensate for the greater cutting rate (of a heavy tool) at the lower part of the cylinder.

For most cylinders, and particularly long cylinders, it is generally preferable to precede the honing by aboring operation. The combined operations take less time and are less expensive.

Obviously the invention is not limited to the details of the illustrative embodiments thereof herein disclosed, since these may be variously modified. Moreover it is not indispensable that all features of the invention be used conjointly since various features may be used to advantage in different combinations and sub-combinations.

Having described our invention, we claim:

1. A device for forming true round and straight bores in cylinders comprising in combination a rotary and reciprocating tool body, a plurality of longitudinally extending honing means radially slidable in said body and each honing means being slidable independently of the other, a flexible impervious tube inside said body bearing against said honing means, said tube having therein a volume of gas such as air under substantial compression to force said honing means outwardly under resilient pressure, the volume of compressed gas inside said tube being suflicient to maintain substantially constant pressure against the stones throughout the honing operation despite stone wear during honing.

2. A device for forming true round and straight bores in cylinders comprising a rotary and reciprocating tool body having a hollow interior. a plurality of longitudinally extending honing means radially slidable in said body independently of each other, an elastic pneumatic tube in said interior, a volume of gas under pressure inside said tube to cause said tube to bear against said honing means to force the same outwardly against the work under honing pressure, the volume of said compressed gas inside said tube being sufiicient to maintain substantially constant pressure against the stones throughout the honing operation without reduction on account of stone wear.

3. A device for forming true round and straight bores for cylinders comprising a rotary and reciprocable tool body having a hollow interior, stone mounting means slidable in and out of said body and carrying honing stones, a. flexible pneumatic tube inside said hollow interior and adapted to bear against said stone mounting means, a volume of compressed gas inside said tube for causing the latter to press said stone mounting means outwardly under honing pressure, means for sealing said tube to prevent accidental escape of gas, the volume of said compressed gas being suflicient to maintain substantially constant pressure against the stone mounting means throughout the honing operation despite stone wear.

4. A device for forming true round and straight bores for cylinders comprising a rotary and reciprocable tool body having a hollow interior, stone mounting means slidable in and out of said body and carrying honing stones, a flexible pneumatic tube inside said hollow interior and adapted to bear against said stone mounting means. a volume of compressed gas inside said tube for causing the latter to press said stone mounting means outwardly, means for introducing compressed gas into said tube, said means permitting variation in the volume of gas introduced to regulate the desired stone pressure, the volume of said compressed gas in said tube being sufficient to maintain substantially constant stone pressure throughout the honing operation despite stone wear.

5. The method of straightening and rounding the bores of long cylinders which is characterized by reciprocating and rotating three or more circumferentially spaced honing stones throughout the bore of the cylinder, pressing the stones outwardly by a sealed volume of air under pressure inside the bore behind the stones to secure uniform stone pressure throughout the length of the cylinder, the volume of air under pressure being suflicient to maintain a substantially constant stone pressure throughout the honing operation without reduction on account of stone wear, and allowing each stone to yield inwardly independently of the other stones when encountering a high spot on the bore while maintaining uniform air pressure on other stones.

VICTOR W. PETERSON. FRANK J. DALEY.

Images