US 3191279 A
Description (OCR text may contain errors)
June 29, 1965 P, ASHURKOFF PRESS-FITTING APPARATUS 2 Sheets-Sheet '1 Filed June 21, 1963 INVENTOR.
I BY l sr fiskmiaf P. ASHURKOFF PRESS-FITTING APPARATUS June 29, 1965 2 Sheets-Sheet 2 Filed June 21, 1963 mvmwon BY ezer .i /hrkoff A T TOE/YE Y United States Patent 3,191,279 PRESS-FITTING APPARATUS Peter Ashurlkofi, Grosse Pointe Farms, Mich, assignor to General Motors Corporation, Detroit, Mich, 211 corporation of Delaware Filed June 21, 1963, Ser. No. 289,644
8 Claims. (Ci. 29-200) This invention concerns an apparatus that utilizes vibratory energy for facilitating the joining of two members having an interference fit.
The use of vibratory energy for press-fitting two members together is not new and one example of an apparatus of this sort can be seen in co-pending patent application Serial No. 225,036, de Wilde filed Sept. 20, 1962, and assigned to the assignee of this invention. The apparatus shown in the de Wilde application includes a fiexural member in the form of a disc which is vibrated while a load is applied to the apparatus in the direction of insertion. The disc is connected to one of two members being press-titted and supplies vibratory energy thereto for jointing the members. Some advantages of this apparatus are that it decreases the time for external load necessary for mating the two members and eliminates galling frequently occasioned by the erratic movement of the inserting member during a conventional press-fitting operation.
The present invention contemplates an improved vibratory apparatus of the above-described type that comprises a flexural bar means coupled to vibration generating means in a manner that permits the latter to provide a resonant standing-wave movement of the bar. Means connect an anti-nodal point of the bar with one of the members to be joined so that the movement at this point is transmitted to that member during the press-fitting opera-ti-on. In the preferred form, the flexural bar means consists of two elongated cylindrical members co-axially fixed to each other in a manner whereby the vibration generating means and the above-mentioned anti-nodal point are located side-by-side. In addition, spring means in the form of elastic bolts are used for connecting the anti-nodal points with the member being inserted so that a unidirectional force is applied by the vibratory apparatus for accomplishing the press fit.
,A more complete understanding of the invention can be derived from the following description taken in conjunction with the drawings, in which:
FIGURE 1 is an elevation view showing a vibratory apparatus made in accordance with the invention and being used for inserting a cylinder liner into an engine block,
FIGURE 2 is an enlarged view taken on line 22 of FIGURE 1, I FIGURE 3 is an enlarged view of the vibration gen,- era-t-ing means taken on lines 3-3 of FIGURE 2, and
FIGURE 4 is a view taken on lines 4-4 of FIG- URE 3.
Referring now to FIGURE 1 of the drawings, for illustrative purposes a preferred embodiment of the vibratory apparatus made in accordance with the invention, and generally indicated by the numeral 10, is shown being utilized for press-fitting a cylindrical liner 12 into a cylinder opening 14 of a block 16. The block is rigidly held in position through suitable hold-down clamps 18 and 20 which maintain the opening 14 in a vertical position for receiving the liner. In the preferred form, the vibratory apparatus is of the hand-operated type and, accordingly, includes a handle portion 22 which permits the operator to grasp and manipulate the apparatus during a press-fitting operation.
More specifically, the vibratory apparatus comprises 'a pair of coaxial flexu-ral bar members 24 and 26, the latter of which supports the vibration generating means general-1y indicated by the numeral 28. Both bars are made in a tubular form with the inner passage 30 in bar 26 serving to connect the vibration generating means 28 with a source 3-2 of pressurized air. A valve 34, located in an air line 36 that connects the air source with the vibratory apparatus, serves to control the amount of air being supplied to the vibration generating means which will be described in more detail hereinafter. The bar member 24, as seen in FIGS. 1 and 2, is of a greater diameter than bar member 26 and has the inner portion thereof suitably bored for concentrically accommodating the latter member. In this connection it can be seen that the upper portion of bar member 26 protrudes through an opening 38 in bar member 24 and terminates with suitable threads which accommodate a nut 40. A tubular spacer 42 is provided between the nut 40 and bar member 24 so that upon tightening the not a shouldered portion 44 of bar member 26 is sea-ted in a counterbore 46. Thus, the two bar members are rigidly connected to each other and the handle portion 22 is formed.
The lower end of bar member 24 has a portion 48 of a reduced diameter that can be piloted onto one of the two members being joined, which in this instance would be the liner 12. In addition, as best seen in FIGS. 2 and 4, a pair of opposed crescent-shaped flanges 50 are integrally formed adjacent the portion 48 and serve to threadably accommodate one end of a pair of bolts or spring members 52. The opposite end of each bolt includes a nut 54 that together with a cap 56 secures the liner to the vibratory apparatus.
As viewed in FIG. 3, the vibration generating means 28 comprises a pair of identical air-driven vibrators, each of which includes a roller-type mass 58 housed within an annular working chamber defined by a cylindrical member 60. A plurality of tangentially directed passages 62 are formed in the member 60 to serve as nozzles for directing a high velocity air stream against the periphery of the mass 58 and thereby cause it to orbit about the Working chamber. The vibrators are laterally spaced firom each other and adapted to have the associated masses driven in opposite directions so as to develop counter-rotating force vectors so that all forces other than those acting in a vertical direction are cancelled. Thus, the effective force acting on the lower end of the bar member 26 is a reciprocating force along the longitudinal axis of the latter at the operating frequency of the vibrators. In this connection, it should be noted that each of the vibrators is made according to the principles stated in the patent to Svenson 2,194,410 and, accordingly, enjoys a frequency step-up which gives a number of force impulses greater than one for each complete revolution of the mass 58 about its axis. As a result, although these vibrators are of a mechanical type, they are able to operate at frequencies much higher than normally attributed to vibrators other than the electrically-driven type.
In assembling or joining two members having an interference fit such .as the illustrated liner and block, the member being inserted would initially be connected to the vibratory apparatus. In this instance, this would be accomplished simply by placing one end of the liner over the reduced diameter portion 48 while piloting the cap member 56 onto the outer ends of the bolts 52. Thereafter the liner would be securely attached to the apparatus by means of the nuts 54. The operator would then position the lead end of the liner into the block opening 14 so as to have the longitudinal axis of the apparatus in alignment with that of the accommodating bore as shown in FIG. 1. Valve 34 would then be opened to direct pressurized air to the vibration generating means 28 so as to drive the vibrators in a counter-rotating manner and thereby develop a reciprocating force, as described above,
which serves to elastically elongate and contract the lower end of bar member 26. This'reciprooating force sets up longitudinal waves which are transmitted through the rigid connection between the barmembers to the portion 48 or the lower end of the bar member 24 so that the latter also experiences an elastic elongation and contraction. V I a Inasmuch as-the portion. 48 is connected with the liner, this'movement, augmented with a small amount of pressure exerted by the operator in the direction of insertion, serves to readily insert the liner into the opening 14 p For most efficient operation it has been found that the vibration generating means should be operated in the I the use of the elasticbolts and would call for the operator to manually position the liner into the'bore after which time the vibratory apparatus would be placed on the liner. Upon energization of the vibrators and with the help of a downward force being applied onto the vibratory apparatus in thedirection of insertion, the liner will be insertedin the opening, however, a noticeable hammering resonant frequency range of the flexural barmembers.
Moreover, it'hasbeen found that optimum results are obtained when both bar members are designed so as to'have equal linear momentum. In this regard'and with refer- 'ence to the particular embodiment of FIGURE 1, both the inner and outer flexural bar members 24 and 26 were made as quarter-Wave-length bars with the point of coneffect will occur between the apparatus and the liner; Moreover, the amount of added force necessary to accomplish insertion in this form of the apparatus would be much greater than when the liner is connected to the latter by the afore-described spring means. b
Although only one vembodiment of this invention has been shown, other forms will be apparent to those skilled in the art of vibratory devices. Therefore, the inventor does not wish to be limited except bythe scope of the appended claims. w
nection between'the two constituting a'nodal point, while the free ends of both bars are anti-nodal points. Thus, the bars together constitute a half-wave-length bar which has, been, in effect, cut in half with the inner ends thereof interconnected so as to place the outer ends adjacent to each other, In this instance, this has been accomplished by inserting one of the bars within the other. As is. well known to those skilled in the science of acoustics, a half wave-length bar vibrated at a frequency equal to or in the range of the resonant frequency of the bar and in a longitudinal standing wave mode has the opposite ends thereof moving in directions 180 out of phase, with the center thereof being a point of minimum movement designated as the nodal point, while the outer ends .are anti-nodal points or points of maximumv movement.
Thus, as explained above, when the vlbrators are operated at or in the range of the resonant frequency of the bar members, the portion 48 elongates and contracts at this frequency. Because of the manner the liner is connectedv with the vibratory apparatus, any inserting'movement caused by the-elongationofthe flexural member. 24 would beoffset by thecontracting movement'thereof and therefore no appreciable insertion could be realized. This, however, is not the case since the bolts by having the intermediate portions thereof of a reduced diameter, act as springs so that the contracting movement ofthe portion 48 causes a 'slight'elongationof the bolts without removing thel-iner. In order to achieve this result, the spring constant of the bolt is relatedto the frictional forcesretaining the liner in the bore. In other words, the frictional force must be greater than the force necessary to cause an elastic stretching of the bolt with? out exceeding the-elastic limit of the latter. a It should be apparent from the above that the use of the elasticbolts is one of the significant features of this,
invention. This is so because, as a practical matter, by providing a spring type connection between the anti-node point of the flexural apparatus utilizes the down stroke for striking the .liner and pushing it into the block, however, on the upstroke the bolt stretches as a spring permitting the apparatus to it would appear that prising an elongated bar means, vibration generating means coupled to one end of said bar means so as to 1 cause a resonant standing-wave movement of the latter in a. longitudinal mode to permit the other end of said bar means to reciprocate in a longitudinaldirection, and means on said other end for engaging one of said two members and thereby transmitting vibratory energy thereto for joiningsaid members together.
2. An apparatus for facilitating the press-fitting of two members together where oneof the members has an opening and the other is to be inserted; into the opening, comprising a bar, vibration generating means. coupled to said '1 bar to cause a standing-wave movement of the latter with nodal and antinodal points along the length of the bar, and elastic means for supporting one .of. said two meme bersrat an antinodal point of said bar. whereby the bar movement at this point is transformed to aunidi'rectional bar member 24 and the liner 12, the
momentarily leave theliner without withdrawing the late ter from the block. Hence, the alternate elongation and contraction at the anti-nodal point of the vibratory apparatus is rectified so that the net effect on the liner is a unidirectional force for inserting the liner.
Finally, it should be noted that during a press-fitting operatiomthe use of an elastic connection between the vibratory apparatus and the member being inserted-is not absolutely necessary. In other words, as seen inxFIG. l, the bolt and cap member could be removed and the apparatus placed on the liner, as shown in FIG. 1, ln'this instance, however the operating procedure would beslightly 7 different than-that explained earlier in connection with force for joining said two members.
3. An apparatus for facilitating the press-fitting of two members together where one of the membershas'an opening an'd'the other is to be inserted into the opening, comprising an elongated bar means, vibration generating means coupled to one end of saidbar means so as to cause a standing-wave movement of the latter in a longitudinal mode to permit the other end of said bar means to rec procate in a longitudinal direction, and elastic means for supportingone of said two members at said other end of said her means whereby the reciprocating movement of said other .end is transformed to a unidirectional force for joining saidtwo members.
' 4. An 1 apparatus for joining two members with an interference fit comprising first and second elastic bars havingthelsame linear momentum, said bars being fixed to each other along alongitudinalaxis, vibration generating means fixed to one of said bars at one end thereof. and adapted to vibrate said bars in a longitudinalmode with a standing-wave whereby the point of connection between said bars is a nodal point while the free end of the other of said, bars is an antinodal point, and means located at said free end of the other of said bars for engagement with one, of said two members for transmitting vibratory energyto the. latter to facilitate the joining operation of said two members.
5. An apparatus for joining two members with an interference fit comprising a first and second bar having the same linearmomentum, said bars being fixed to each other along a longitudinal axis, a pair of fluid-driven vibrators fixed to one of said bars at one end thereof and adapted to vibrate said bars in a longitudinal mode with a standing-wave wherebythe point of connection between said bars is a nodal point while the free end of the'other of said bars is an antinodal point, and means located at said free end of the other of said bars for engagement with one of saidtwo members for transmitting vibratory energy to 5 the latter to facilitate the joining operation of said two members.
6. An apparatus for joining two members with an interference fit comprising first and second elongated bars having the same linear momentum, said first bar having an elongated opening formed therein along its longitudinal axis, the second bar located in said opening and connected at one end to the first bar, vibration generating means fixed to the second bar at the free end thereof and adapted to vibrate said bars in a longitudinal mode with a standing-wave whereby the point of connection between said bars is a nodal point while the free end of the first bar is an antinodal point, and means located at said free end of the first bar for engagement with one of said two members for transmitting vibratory energy to the latter to facilitate the joining operation of said two members.
7. An apparatus for joining two members with an interference fit comprising an elongated cylindrical first bar having a longitudinal passage for compressed air formed therein, a pair of air-driven counter-rotating vibrators connected to one end of said bar and communicating with said passage, a sleeve-shaped second bar of substantially the same linear momentum as said first bar, said first bar being located within said second bar and being fixed to one end of the latter, the other end of said second bar being provided with elastic means for supporting one of said two members during the joining operation, and a source of compressed air for driving said vibrators at the resonant frequency of the bars whereby the latter vibrates with a standing-wave in a longitudinal mode.
8. The apparatus of claim 6 wherein each of said vibrators comprises a roller adapted to be driven in an orbital manner so as to generate a rotating force vector in a plane parallel to the longitudinal axis of said first and second bars.
References Cited by the Examiner UNITED STATES PATENTS 2,194,410 3/40 Svenson 259-1 2,561,577 7/51 Knudsen 173-132 WHITMORE A. WILTZ, Primary Examiner. THOMAS H. EAGER, Examiner.