US3393473A

US3393473A - Spring grinding machine

Info

Publication number: US3393473A
Application number: US463493A
Authority: US
Inventors: Stanley M Rimmer
Original assignee: Associated Spring Corp
Current assignee: Associated Spring Corp
Priority date: 1965-06-14
Filing date: 1965-06-14
Publication date: 1968-07-23
Anticipated expiration: 1985-07-23

Description

July 23, 1968 s. M. RIMMER SPRING GRINDING MACHINE 3 Sheets-Sheet 1 Filed June 14, 1965 Ill. III-I lllllli INVENTOR STANLE Y M. R I MM E R ,Jmgmw fiww 2 W 9 2M ATTORNEYS July 23, 1968 s. M. RIMMER SPRING GRINDING MACHINE 5 Sheets-Sheet Filed June 14, 1965 Lm 2 I n o yl II, 3 M I 4 m w W m m Vw m 4 1 I m H m \P I| O /0 0 I INVENTOR STA N LEY M. R l M MER m JMM 9 am ATTORNEYS July 23, 1968 s. M. RIMMER SPRING GRINDING MACHINE 3 Sheets-Sheet 3 Filed June 14, 1965 INVENTOR STAN LE Y M. R I M M ER Juli/0M2! a mmammwm ATTORNEYS United States Patent 3,393,473 SPRING GRINDING MACHINE Stanley M. Rimmer, Hartford, Conn., assignor to Associated Spring Corporation, Bristol, Conn., a corporation of Delaware Filed June 14, 1965, Ser. No. 463,493 1 Claim. (Cl. 51112) ABSTRACT OF THE DISCLOSURE A machine for grinding the ends of helical coil springs by passing them on an endless belt between aligned hollow center grinding wheels over an arctuate path which is of maximum possible length and at the location of maximum wheel speed, the path being located at the aligned outer peripheries of the grinding wheels and extending over approximately 250 of arc of the wheel surfaces. The endless belt is supported between the grinding wheels on a guiding wheel which is rotatably mounted on a support which is itself supported on the machine frame outside the peripheries of the grinding wheels so that the belt may be removed from the grinding wheels to permit them to be dressed.

The invention relates to machines for grinding the ends of helical compression springs in order to provide fiat end surfaces for seating on the parts upon which the springs are intended to bear. Grinding machines of the type to which the invention relates are those comprising two wheels having spaced parallel or canted grinding surfaces between which the springs or other articles are passed or positioned so that the opposite ends of the springs are ground by the respective grinding surfaces.

Spring grinding of the type and for the purpose to which the invention relates is an old art and has been usually practiced in either of two ways which are described as follows. In accordance with the first of these practices hollow grinding wheels, i.e., those having opposed center holes, are used and the springs are passed across the annular grinding surfaces, the advantages of this construction and practice being that grinding at the dead center parts of the wheels is avoided, thus increasing the efficiency of grinding by performing it at regions of higher wheel speed, and at the same time causing more uniform Wear on the wheels, thus decreasing the problems of dressing the wheels. In the second of the conventional practices in the art solid wheels, i.e., those without center holes, are used and the springs are passed across the aligned wheel centers, usually in an arcuate path, thus providing a continuous path of spring travel with consequent increased time of grinding and increased stock removal for each passage of the springs over the wheels.

The present invention relates to spring grinding of the general type of these two known practices, and has for its principal object to provide improved apparatus for grinding the ends of springs and like objects by which the efiiciency of grinding is greatly improved. The objectives of all spring grinding practices are, of course, to remove metal at least cost and in the shortest time, and to produce end surfaces of the most accurate squareness. These are the basic objectives of the present invention and they are achieved in accordance with the invention by grinding at an area of the grinding wheels at which there is an optimum condition which is the resultant of long length of the grinding path, regardless of whether the springs are moving or fixed, and the greatest speed of movement of the grinding surfaces over the spring ends consistent with the requirement of long grinding path length. The invention departs from the previous grinding prac- See tices described above to provide apparatus for spring grinding which produce the advantages of a longer grinding path and grinding at areas of highest grinding wheel surface velocity, thus achieving the advantages of both of the known grinding procedures. In accordance with the preferred concept and embodiments of the invention wheels having center holes are used and grinding is performed entirely in the area of maximum surface speed of the wheels and along a path of contact between the grinding surfaces and the springs which is of maximum optimum length.

The invention is described in the following specification and is illustrated in the accompanying drawing, in which:

FIG. 1 is a top elevational view of a spring grinding machine as provided by the invention;

FIG. 2 is a side plan view of the machine disclosed in FIG. 1;

FIG. 3 is a sectional view taken on line 33 of FIG. 1;

FIG. 4 is a top plan view of a second embodiment of the invention;

FIG. 5 is a side elevational view of the embodiment disclosed in FIG. 4;

FIG. 6 is a top elevational view showing a modified path of spring travel over any of the grinding wheels;

FIG. 7 is a vertical part-sectional view through another form of grinding machine according to the invention;

FIG. 8 is a sectional view taken on line 88 of FIG. 7, and

FIG. 9 is a partial view similar to FIG. 2 and showing a further embodiment of the invention.

In a first embodiment of the invention, which is disclosed in FIGS. 1, 2 and 3, one or a number of pairs of spaced grinding wheels are provided and the springs to be ground are pressed on an endless belt between the wheels of each pair along a path which is not only at or closely adjacent the outer peripheries of the opposed grinding surfaces of each pair of grinding wheels but also lies on the side of the center of each pair of wheels which is opposite to the side from which the endless belt approaches the pair of grinding wheels and to which it moves from such pair, whereby the belt passes around the center of each pair. The invention therefore provides a new combination of peripheral high speed grinding and grinding at and along a path of maximum optimum length, with consequent greatly improved results in metal removal per unit of time and per unit of power.

This first embodiment of the invention comprises two hollow

center grinding wheels

2, 4 which are mounted, respectively, on the substantially vertically aligned shafts of driving motors 6, 8 and which have horizontal, vertically spaced, annular grinding surfaces 10, 12 which are located at and adjacent the peripheral edge parts of the wheels and at least parts of which are outside the annular line of approximately two-thirds maximum surface speed of the wheels. The grinding surfaces may be parallel, as shown in the drawings, or may be slightly canted with respect to each other, in either case in accordance with known practice in the art.

Means are provided by the invention for passing helical compression springs between the opposed grinding

surfaces

10, 12 along the path described above, which is at and adjacent the outer peripheral edges of the grinding surfaces and at a part thereof which is on the far side of the grinding wheel centers with respect to the part of the belt which is not between the grinding surfaces. Such means comprise an endless belt 20 which is formed of cylindrical work carriers 22 which are pivotally connected to each other as at 24 to form an articulated endless belt of any suitable length to fit the machine with which it is used. Each work holder 22 has a circular opening therethrough to receive a spring 26 and these work receiving openings are so positioned with respect to the endless belt and with respect to the grinding wheels that the endless belt carries each spring between the grinding surfaces in a position in which the axis of the spring is normal to the opposed grinding surfaces.

Means are provided by the invention for imparting movement to the endless belt along the endless path thereof, and such means comprise a driving wheel 30 which is mounted for rotary movement about an axis which is parallel to the aligned axes of the grinding

wheels

2, 4 and is laterally spaced therefrom. The driving wheel comprises spaced upper and lower

circular plates

34, 36 connected by a central member 38 and having

peripheral parts

40, 42 which extend radially outwardly from the central part 38 to provide a peripheral space between the upper and

lower members

34, 36. Each of the work holders 22 of the endless belt has connected thereto on the inside of the belt an inwardly extending part 44 which has the same vertical dimension as the space between the

peripheral parts

40, 42 of the driving wheel whereby the rotation of the driving wheel will be frictionally imparted to the endless belt. The outer diameter of the driving wheel is approximately the same as the inner diameter of the annular grinding surfaces as most clearly shown in FIG. 1, whereby the springs positioned in the work holders will be moved by the endless belt between and across the annular grinding surfaces. A driving means 50 is provided to impart rotary movement to the driving Wheel.

Means are provided by the invention for guiding the endless belt and the springs carried thereby along the described path between the grinding surfaces. Such means comprise a guiding wheel 60 which is positioned between the two grinding wheels as is most clearly shown in FIG. 3. This guiding wheel comprises vertically spaced, circular upper and lower plates 62, 64 which are connected at their centers by hub 66 which is journaled in ball bearing within the end of a supporting member 68 whereby the guiding wheel may be rotated. The diameter of the upper and lower plates 62, 64 is approximately the same as the diameter of the inner periphery of the annular grinding surfaces 10, 12 of the grinding wheels, as most clearly shown in FIG. 3. The space between the peripheral parts of the upper and lower plates 62, 64 is equal to the thickness of the members 44 which extend inwardly from the work holders 22 of the endless belt 20, whereby these members 44 will be received between the plates of the guiding wheel as the belt approaches the wheel. No rotary driving force is applied to the guiding wheel as movement is imparted to the belt entirely by the driving wheel 30.

As described above, the diameter of the upper and

lower plates

40, 42 of the driving wheel 30 is the same as the diameter of the inner periphery of the grinding surfaces 10, 12 and the

reaches

80, 82 of the endless belt which extend between the driving and grinding wheels will therefore be substantially parallel to each other. Because of this, the work holders 22 enter and leave the opposed grinding surfaces at points which are spaced an optimum close distance from each other, as particularly shown in FIG. 1, in which the entrance and exit points are shown at 84, 86, thus providing an active grinding path of substantially maximum length for a belt type grinding machine. It will be seen from FIG. 1 that over the segments A and B the springs are progressively entering or leaving the space between the two grinding surfaces, while over the segment C the springs are entirely within the space between the grinding surfaces. The arcuate segments A and B extend over approximately 20 of arc, while the segment C extends over approximately 210 of arc, and the ends of the springs are therefore entirely between the grinding surfaces over an are which is a maximum for all practical purposes in this type of grinder. This are of grinding surface is at or adjacent the area of maximum surface speed of the grinding surfaces and is also on the back path side of the grinding surfaces with respect to the position of the driving wheel and the travel of the belt in approaching and leaving the grinding wheels. Because of these factors, which are provided by the invention, the springs are ground over a path of maximum length at the area of maximum surface speed of the grinding surfaces, thereby producing maximum metal removal per unit of time and per unit of power expended.

Means are provided by the invention for facilitating the loading and unloading of springs into the work holders 22 of the endless belt. Such means comprise a flat plate which underlies the driving wheel 30 on the side thereof removed from the grinding wheels and which provides a base or stop for springs loaded into the work holders, as particularly shown in FIG. 2. This plate has a part 92 extending toward the grinding wheels so that it prevents the springs from falling out of the work holders as they pass from the driving wheel to the grinding wheels. The plate also has a part 94 on the delivery side of the grinding wheels so that the springs will be held in the work holders until they have passed entirely from between the grinding surfaces. In the preferred form of the invention the plate, on the delivery side of the grinding wheels, stops short of the driving wheel at edge 96 so that the springs will drop by gravity from the work holders after passing this edge.

It will be apparent that in the embodiment of the invent disclosed in FIGS. 1 to 3 the springs may be passed between the grinding wheels more than one time in order to remove any desired amount of metal or produce any desired condition of the ends of the springs. However, in accordance with the invention two or more sets of grinding wheels may be provided instead of the one set of the embodiment of the invention which is described above. A grinding machine in accordance with this second embodiment of the invention is disclosed in FIGS. 4 and 5 and comprises two laterally spaced sets of hollow

center grinding wheels

100 and 102, the wheels of each pair being mounted on the aligned vertical shafts of driving motors 104. As in the other embodiments of the invention, the grinding surfaces of the hollow center wheels are entirely at and adjacent the outer peripheral parts of the wheels and therefore travel at the maximum surface speeds of the wheels.

Means are provided in this embodiment of the invention for passing helical coil compression springs between the grinding surfaces of the two sets of wheels, and such means comprise an endless articulated belt 108 having the same construction as the belt 20 which is described above in connection with FIGS. 1 to 3. This belt is trained around the outer peripheral parts of both of the two sets of grinding wheels, by which it is meant that the part of the belt at each wheel passes around the center of the wheel and is therefore between those parts of the grinding surfaces of each wheel which are on the opposite side of the center of the wheel from the other wheel. Thus, the advantages of grinding along a continuous path of maximum length and at areas of maximum surface speed of the grinding surfaces are produced as in other embodiments of the invention and with the same consequent advantages.

The belt 108 may be driven along its endless path by suitable driving means such as shown at 110. Guiding

wheels

112 and 114 are provided at each of the grinding wheels and have the same construction and function as the guiding wheel 60 which is described above in connection with FIGS. 1 to 3. In addition, a plate 116 is provided which underlies the reaches of the endless belt between the two sets of grinding wheels to prevent springs from falling from the endless belt and also to provide stations for loading and unloading springs from the endless belt.

In the two embodiments of the invention described hereinbefore the endless belt carriers are so arranged and positioned that the springs are carried thereby along a path concentric with the grinding wheels after fully entering between them. However, in further accordance with the invention the path of movement of the invention may be modified to cause the springs to move along a path which is eccentric to the grinding wheels. Thus, as shown in FIG. 6 the path of spring movement between the grinding surfaces is removed a maximum distance from the center of the wheels at the points of entry and

exit

122, 124 respectively, at both of which the springs are adjacent the outer peripheries of the grinding surfaces, and is a minimum distance from the wheel centers at a point 126 midway between the points of entry and exit, at which point the springs are closely adjacent the inner peripheries of the grinding surfaces. In following this eccentric path each of the springs traverses substantially the entire radial extent of the grinding surfaces, with resulting increased even wear of the grinding surface and reduced need for dressing them. It will be apparent that in any of the embodiments of the invention the path of spring travel may be made eccentric to the wheel centers, rather than concentric, and the parts of the embodiments of FIGS. 1 to 3 and 4 and 5 other than a single pair of grinding wheels and the eccentrically positioned spring carrying belt are not shown in FIG. 6.

A still further form which the invention may take is disclosed in FIGS. 7, 8 and 9 of the drawings, and this embodiment utilizes paddle type work carriers which move the springs to a position between the grinding surfaces where they are held in fixed positions until completion of the grinding operation. The work positioning means of each paddle are so positioned with respect to the grinding surfaces that when each paddle is inoperative, grinding position between the wheels the springs are at or adjacent the area of maximum surface speed of the grinding surface and maximum length of travel of the surfaces with respect to the springs during each revolution of the wheels.

A machine according to this embodiment of the invention may comprise a base 30 supporting two vertically spaced

grinding wheels

132, 134 having grinding

surfaces

136, 138. In the embodiment shown in the drawings the grinding wheels and surfaces are horizontal and therefore at least the lower grinding member must be solid, i.e. not of the hollow center type. In this case the hollow center of the lower wheel is covered or filled with a soft abrasive material, chalk or other filler 139 so that springs being moved between the grinding wheels will not fall into the hollow center of the lower wheel. If, however, the grinding wheels are mounted on horizontal axes and have vertical grinding surfaces both grinding members may be of the hollow center type. In either case all grinding is performed at and adjacent the outer periphery of the grinding surfaces, i.e. at areas of maximum surface speed and maximum annular length. The grinding wheels are driven, respectively, by separate motors (not shown) through belt drives 140, 142 and vertically aligned

drive shafts

144, 146. The grinding wheels and associated parts are mounted for vertical movement with respect to each other and this may be accomplished by a hydraulic cylinder 148 and piston 150 which may operate through a rack and gear mechanism 152 to move the upper grinding wheel and its associated parts toward and away from the lower wheel.

Means are provided by the invention for moving springs into and out of grinding position between the grinding

surfaces

136, 138 and such means comprise basically a horizontal work carrier indicated generally at 154 which is of planar shape and has three

circular work holders

156, 158, 160' which are spaced equidistantly about a vertical shaft 162- to which the carrier is fixed and by which it may be indexed through 120 steps by any suitable means. A plurality of work holders are provided so that one may be in a loading position, while the second extends into the grinding area between the grinding wheels, and the third is in a position in which the finished springs may be removed from the holder after grinding, the work holders being shown in FIG. 2 in these three positions in the

order

160, 156, 158 in FIG. 8. Each work holder has a plurality of work holding openings 164 extending therethrough, and to hold the workpieces in these openings an underlying stationary plate 166 is provided, one part of which, 168 extends from the loading station to the periphery of the lower grinding wheel with its upper surface flush with the grinding surface of that wheel. The plate also has a part 170 adjacent the exit side of the grinding wheels and extending to an edge 172 adjacent the work unloading position so that the springs will be carried beyond the grinding wheels before dropping out of the holes in the work holder as they pass the edge 172 of the plate. The work holders are adapted to be intermittently indexed about their pivotal support at 162, and the springs remain in the grinding area until brought down to size before being indexed to the unloading position.

Before any work holder with springs therein is moved into the grinding area, the grinding wheels are moved apart by

means

148, 152 sufficiently to permit one of the work holders and the springs carried thereby to be moved from the loading position to grinding position, and the upper wheel is then moved downwardly to grinding position. The wheels are rotated during and after the downward movement of the upper wheel to effect grinding of the ends of the springs in the holder positioned between the wheels, and when the desired amount of grinding has been accomplished the rotation of the wheels is stopped, the upper grinding wheel is retracted upwardly and the work carrier is indexed to move the paddle 156 to the work discharging position, the paddle to the grinding position and the paddle 158 to the loading position, after which the upper wheel is moved downwardly to grind the springs.

In accordance with the invention, each of the work holders or paddles is provided with an annular series of spaced holes 164 each of which extends therethrough and within each of which a spring is placed at the loading position so that it will be carried to the grinding position with its axis normal to the grinding surfaces. Each of the paddles is of such lateral area and each of the annular series of work receiving openings in each panel is so positioned on the paddle and is so related in diameter to the diameter of the grinding surfaces that the springs within the openings are engaged and ground by the grinding surfaces only at and closely adjacent the outer peripheries of the two grinding surfaces. These are the areas of maximum surface speed and maximum length of the grinding surfaces and the positioning of the springs at this area during the entire grinding operation provides the maximum removal of metal per unit of time and power in accordance with the basic concepts of the invention.

In the embodiment of the invention disclosed in FIGS. 7 and 8 the work receiving openings in all of the paddles are so positioned with respect to the annular grinding surfaces that each annular series of work receiving openings' is concentric with the grinding surfaces when the paddle containing them is between the grinding wheels. However, each annular series of work receiving openings may be eccentric to the grinding surfaces, and this construction and arrangement has advantages in causing more even wearing of the grinding surfaces. This eccentric arrangement is shown in FIG. 9 of the drawings wherein the annular series of work receiving openings in paddle 182 are eccentric to grinding surface 54.

While I have described and illustrated a number of forms which my invention may take, it will be understood by those skilled in the arts to which it pertains that other embodiments, as well as modifications of those disclosed, may be made and practiced without departing in any way from the spirit or scope of the invention, for the limits of which reference must be made to the appended claim.

7 What is claimed is: 1. A machine for grinding the ends of helical compression springs, comprising a horizontal driving wheel rotatably mounted on a vertical shaft, means for rotating said driving wheel, two hollow center grinding wheels mounted respectively on substantially vertical aligned shafts and having vertically spaced grinding surfaces at and adjacent only the outer peripheral parts thereof, means for rotating said grinding wheels, the driving wheel and the grinding wheels being laterally spaced, an endless belt trained about the driving wheel and having parts engaging the driving wheel for imparting movement to the belt along its endless path, a plurality of vertical cylindrical spring carriers carried by said endless belt, a guiding wheel for the endless belt disposed between and parallel to the grinding wheels, an elongated member supported at its one end outside the peripheries of the grinding wheels and extending between the peripheries of the grinding wheels and there rotatably supporting the guiding wheel, said guiding wheel having vertically spaced side plates peripherally aligned with the hollow centers of the grinding wheels, said endless belt being trained about the periphery of said driving wheel on the opposite side of the center thereof from the guiding wheel whereby the spring carriers are guided between the outer peripheral parts of the grinding wheel surfaces and around the aligned centers of the grinding wheels.

References Cited UNITED STATES PATENTS 1,142,700 6/1915 Halstead 51-112 1,262,529 4/1918 Lowe 51-134 X 1,527,808 2/ 1925 McIntyre 51-111 X 1,646,132 10/1927 Barry 51-134 1,956,700 5/1934 Shelly 51-110 2,398,463 4/1946 Rumsey 51-134 X 2,753,667 7/1956 Whitelaw 51-118 FOREIGN PATENTS 7,559 3/1897 Great Britain.

451,290 8/ 1934 Great Britain.

979,361 1/ 1965 Great Britain.

HAROLD D. WHITEHEAD', Primary Examiner.