US3060539A - Conduit forming machine - Google Patents

Description

0a. 30, 1962 D. N. NORTON 3,060,539

CONDUIT FORMING MACHINE Filed Nov. 24, 1958 4 Sheets-Sheet 1 INVENTOR.

v g ,7, h g ag B z War Oct. 30, 1962 D. N. NORTON CONDUIT FORMING MACHINE 4 Sheets-Sheet 2 Filed Nov. 24, 1958 ATTO/P/VEVJ Oct. 30, 1962 D. N.'NORTON CONDUIT FORMING MACHINE 4 Sheets-Sheet 3 170u7/0J A f Nor fan INVENTOR.

BY a I I ATrQ/PMEVJ Filed Nov. 24, 1958 ZZV/ Oct. 30, 1962 D. N. NORTON 3,060,539

CONDUIT FORMING MACHINE Filed NOV. 24, 1958 4 Sheets-Sheet 4 wilfk f ATTORNEY? 3,060,539 Patented Oct. 30, 196.?

3,060,539 CONDUiT FORMING MAHENE Douglas N. Norton, Bellaire, Tex., assignor of small interests to various assignees Filed Nov. 24, 1958, Ser. No. 776,083 3 Claims. (Cl. 2536) This invention relates to machines for manufacturing multihole conduits such as the conduit utilized in laying underground communication cable or the like.

The present general practice in laying underground cable for communication lines is to run cables through buried conduit. Multicell or multiduct conduit is utilized. The conduit employed most widely in the past has been a fired clay. This product requires a clay of very particular qualities and in available in limited quantities. Until recently there has not been an adequate alternative for this product.

Recently a machine has been provided for manufacturing multihole conduit from concrete or the like which may be utilized in running cable and for other purposes for which conduit may be used. In that machine, a plurality of packer heads is employed, each somewhat similar to the single packer head employing a packer or slinger and a tapered troweling skirt used in fabricating single bore concrete conduit. In such a machine the rotating packer heads in effect provide packing walls for each other; that is, one packer head in rotating packs against an adjacent packer head, and it is not necessary to have a wall of the mold surrounding each packer head.

The present invention has for its general object the avoidance of certain difficulties which have arisen in connection with this concrete conduit forming machine which was used prior to this invention, and the provision of a machine which will produce an improved conduit.

In molding small diameter bores it has heretofore been felt necessary both in connection with single duct concrete conduit and in connection with multiduct concrete conduit to mount the packer heads on relatively small diameter shafts and to stabilize such packer heads against whipping as the shafts rotate by providing followers which engage the packer heads at the beginning of their opera tion at one end of the mold and follow packer heads through the bores as the conduit is formed. These followers were required to be of sufiicient diameter to stabilize the packer heads against whipping and in some cases they were made of a diameter which would trowel the walls of the bore to further smooth them after the passing of the packer heads.

The necessity for such followers included the necessity for a substantial amount of mechanism to operate them in addition to the provision of the followers themselves and their mountings.

'It was also formerly thought necessary in forming a conduit with a plurality of bores separated by a web which was not in contact with the wall of the mold, to so arrange the packer heads, each of which has a slinger section or packer leading a troweling section in operation, that the slingers of some heads would be opposite the troweling sections of other heads, alternate packer heads being preferably so arranged.

This necessitated packer head mounting and driving shafts of different lengths and, hence, a greater inventory of spare parts, as well as somewhat greater skill required in assembly of the machine after repairs.

The packers heretofore employed have usually been in two parts on opposite sides of the packer head axis so that they could be adjusted to compensate for rapid wear. These have not only worn rapidly and hence required frequent checking and adjustment but have tended to move toward each other, thus destroying the gauge of the duct formed, and have collected concrete mix between them, reducing their efiiciency and increasing their frictional resistance to rotation and scoring the walls of the bores.

The troweling portions of the packer heads, sometimes called skirts, have been generally of a length not much if any greater than their diameters, have had an outer surface slightly tapered downwardly, and have had smooth exteriors of circular cross-section in order to reduce frictional resistance to rotation. This shape not only provided little guiding and made the followers either necessary or desirable, but produced an inferior troweling job.

Previously it was generally thought immaterial in which direction they rotated, although in at least one instance a person active in this field laid down the requirement that alternate packer heads must rotate in opposite directions. However, it has been discovered that when two adjacent packer heads do operate in opposite directions they tend to pack the material on one side of a line between their axes more tightly and on the other side of such line tend to loosen the material, and there results a product which is inferior for this reason.

It has also been observed that in previous machines using molds with square corners or corners beveled to provide square or beveled outer corners on the conduits, the entire outer surfaces of the conduits were not as smooth and compact and free from voids as desirable.

It has been found that in such machines not only do the packers or slinger sections and the troweling sections of the packer heads wear fairly rapidly when made as they have been in the past, and thus require frequent replacement, but also that the shafts on which they have been mounted have Worn quite rapidly adjacent the packers and have required frequent replacement. All of these parts, especially the shafts, are quite expensive and their replacement substantially increases the cost of operating the machine.

It is, therefore, a general object of this invention to obviate the difiiculties above outlined which have been encountered with previous machines.

More specifically, it is an object of this invention to provide a machine of the character above mentioned in which followers for the packer heads will be unnecessary.

Another object of this invention is to provide a less expensive structure for packer heads for machines of this character.

Another object of this invention is to provide a packer head construction for a machine of this character in which the different wearing parts of the packer head may e separately replaced so that in the event one part wears so as to require replacement without other parts wearing to that degree, the part which wears excessively may be replaced and the other part retained.

Another object of this invention is to provide a packer head structure which will be subject to only a fraction of the wear encountered in previous structures and will therefore have much longer life.

Another object is to provide a packer or slinger which will not wear rapidly or move inwardly in use and thereby destroy the desired gauge of ducts, and which will not collect concrete mix and cause friction and scoring of the duct walls.

Another object is to provide an elongated trowelling skirt section of uniform diameter along its length which will provide packer head guidance and a better troweling action without excessive friction and wear over the troweling and guiding surface.

Another object is to avoid the uneven packing of concrete mix in webs between ducts formed by adjacent packer heads.

Another object is to provide for a more thorough and smooth flowing mixing action in the concrete mix with in a form during the forming operation and the avoidance of turbulence within such mix.

Another object is to produce a concrete conduit having smoother and more continuous and dense duct walls than has been possible with previous equipment.

Another object is to produce a concrete conduit having smoother and more continuous and dense outer surfaces than has been possible with previous equipment.

Another object of this invention is to provide a packer head driving structure for a machine of this character in which the wear in the driving shaft heretofore encountered just above the packer heads will not require frequent replacement of driving shafts as has been true in the past.

Another object of this invention is to provide a machine of this character in which the advantages heretofore gained by placing one packer head slightly in advance of the other so that the packer of the second packer head would be substantially opposite the troweling section of the first packer head, may be obtained without necessity for thus staggering the positions of the packer heads and hence without necessity for shafts of different lengths for the respective packer heads.

Other objects and advantages of this invention will become apparent from the following description taken in connection with the accompanying drawings in which are set forth by way of illustration and example certain preferred embodiments of this invention.

In the drawings:

FIG. 1 is a front elevational view of a multiduct conduit forming machine constructed in accordance with this invention, parts being broken away and shown in crosssection for purposes of illustration, the parts being shown in the position they occupy at the end of the forming operation.

FIG. 2 is a fragmentary view similar to the central portion of FIG. 1 but illustrating the machine with the parts in the position they occupy at the beginning of the forming operation.

FIG. 3 is a fragmentary transverse cross-section through the driving gears of the machine shown in FIG. 1 taken substantially along the line of 3-3 of FIG. 1.

FIG. 4 is a view similar to FIG. 3 but taken along the line of 4--4 of FIG. 1.

FIG. 5 is a transverse cross-sectional view through the form and just above the packer heads during the forming of a conduit, but with the loose concrete mix above the packer heads omitted, and being taken substantially along the line 55 of FIG. 2.

FIG. 6 is a longitudinal cross-section through a packer head constructed in accordance with this invention.

FIG. 7 is a transverse cross-section through the Packer head of FIG. 6 taken along the line 7-7 of FIG. 6.

FIG. 8 is a view similar to FIG. 7 but taken along the line 88 of FIG. 6.

FIG. 9 is a view similar to FIGS. 7 and 8 but taken along the line 9--9 of FIG. 6.

FIG. 10 is a view similar to FIG. 6 but showing a modified form of packer head.

FIG. 11 is a view transverse to the longitudinal axis through the packer head shown in FIG. 10 and taken along the line 11-11 of FIG. 10.

FIG. 12 is a view similar to FIG. 11 but taken along the line 12-12 of FIG. 10.

Reference is first had to that aspect of this invention which has to do with the elimination of followers for engaging the packer heads and following them through the forms in the forming operation in order to maintain them in alignment.

It has been discovered that by making that portion of the packer head which was formedly regarded as merely a troweling section for troweling and smoothing the already formed interiors of the ducts, so that it is substantially cylindrical on its exterior surface for an axial distance of at least twice its diameter, it will be given 4 l sufiicient bearing on the wall of a duct which the preceding slinger or packer section has already formed so that it will serve as a stabilizer and guide for the packer head and eliminate the necessity for the follower previously employed.

It has further been discovered that by forming the outer surfaces of these troweling sections with longitudinally extending circumferentially spaced slightly protruding beads or ridges, preferably blended to the adjacent cylindrical surfaces of the troweling sections, the frictional resistance to rotation is reduced and a greatly superior troweling action produced, with much smoother and denser duct walls than heretofore throught possible. By making these ridges of very hard and wear resistant material the life of the troweling sections was greatly increased.

It has further been discovered that by making those surfaces of the packer sections which initially sling the mix radially outwardly and form the duets with a surface of hard, wear-resistant material, the necessity for ad justment could be avoided and the packer section made of a unitary member with opposed compression wings to do the slinging and duct forming. This in turn avoided the objectionable movement of these parts toward each other with consequent loss of gauge. The use of a metal compression wing unit surfaced with such material as tungsten carbide on the slinging and forming surfaces has proved satisfactory and any wear tending to destroy gauge can readily be compensated for by applying additional hard material. More desirable, although initially more expensive is the use of a compression wing unit made of ceramic or the like which has been found to outlast the hard surfaced metal units by several times. It has also been found that by shaping such a unit properly on its external surface, the accumulation of concrete mix thereon will be avoided.

Another phase of the invention has to do with the rotation of all of the shafts carrying packer heads in the same direction. in an effort to remedy the ditliculty of uneven packing observed when some packer heads rotate opposite to others, arrangement was made for the rotation of all heads in a group in the same direction. Contrary to previous belief, it was found that such an arrangement resulted in a product more uniformly packed and substantially superior to the product therctofore pro- Vided.

The combined effect of the beads on the troweling sections and the rotation of all heads in one direction has been to increase the circulation and intimacy of the mix in the forming operation. It has also been discovered that a wholly unforseen reduction of turbulence of the mix during such circulation results from making the corners of the form round instead of angular. An unexpected improvement in the smoothness, density and perfection of the entire outer surface of the conduit results, along with some improvement in the entire conduit.

It has further been found that with the troweling sections at least twice as long as their diameters and with the rotation of all heads in one direction, all heads may be mounted approximately in lateral alignment with each other thereby eliminating the necesity for shafts of different lengths for the different heads operating in a single form.

In another aspect of this invention having to do with the reduction of wear and thereby increasing the life of the parts of a machine of this character, this invention employs several expedients.

First of all, in order to provide for a truly concentric mounting of the packer head on the shaft on which it is carried and thus avoid any lateral vibration when the same are rotated, and at the same time to insure tightness of the packer head on the shaft and prevent any looseness or wobble of the head with respect to the shaft, the mounting of the packer head on the shaft has been made in the form of a tapered end on the shaft and a tapered central or axial opening in the packer head such that when the packer head is forced onto the shaft it will wedge tightly thereon in accurate axial alignment and in true concentricity therewith. It is then drawn tightly into place on such tapered shaft end by means of a hold-fast means capable of being tightened, such as a threaded bolt or the like.

Second, it has been found that the troweling sections of the packer heads even when made in accordance with this invention wear and are subject to breakage to such degree as to require replacement at intervals. The major portions of such sections in accordance with this invention are made in the form of sleeves requiring no special machining or forming except that their outer surfaces be smooth and substantially cylindrical with slightly protruding longitudinal beads. Their end surfaces are accurately formed at right angles to the axis of the sleeve or tubular member. Such sleeve preferably has its exterior surface of the diameter required for the exterior of the troweling section. The portion of the packer head which has a taper fit with the shaft, provides a hub with an endwise facing shoulder likewise accurately formed on a plane at right angles to the axis so as to receive the end of the tubular member. Preferably this hub is also formed with its exterior surface of the same outer diameter as the tubular member so that it will form a continuation of the tubular member and add somewhat to the length of the troweling section. The tubular member is appropriately keyed to the hub so that it will rotate therewith at all times and when drawn tightly against the shoulder above mentioned will be accurately and rigidly aligned with the hub and hence with the shaft on which the packer head is mounted. Thus the exterior surface of the hub forms, in effect, a portion of the troweling head but the major portion of the troweling section of the head is a tubular member which may readily be replaced without necessity for replacing the hub that requires fitting on the shaft.

Provision is made in accordance with this invention for tightening such tubular troweling section against the hub and for tightening the hub on the shaft by means of a single tightening element in the form of a bolt, capscrew, or the like, extending entirely through the tubular troweling section and threadedly engaging the end of the shaft. Engagement between such bolt or the like and the end of the tubular troweling section opposite the hub, is by menas of a tapered nose section. This section serves also the function of guiding the forward end of the troweling section as it is moved into position to begin the forming operation.

In order to extend the life of the tubular troweling sections such as just mentioned it is also proposed by this invention that either the troweling sections be made of such highly resistant material as porcelain which is cap able of great resistance to wear and has actually shown little or no wear over an unusualy long period of use, or of a tubular member of metal or the like having inlaid into its outer surface at circumferentially equally spaced positions longitudinally extending beads of hard surfacing material such as tungsten carbide or the like. The outer surfaces of such beads are preferably ground substantially smooth but allowed to protrude slightly beyond the outer surfaces of the tubular members.

One other expedient for reducing the effects of wear involves the forming of the slinger or packer sections of the packer heads of porcelain or, alternatively, of a relatively soft metal with a hard facing on its outer surface of tungsten carbide or similar material.

Another expedient for reducing the necessity for re placement of relatively expensive parts is that of providing a removable sleeve over the lower end of each of the shafts carrying packer heads. This is the Zone of the shaft which is subjected to greatest wear due to engagement with cement mix about to be packed by the packer heads. Such sleeve is rigidly clamped on the exterior it! of the shaft so that it takes the wear. inexpensive and very readily replaced.

Referring now more in detail to the drawings, there is shown in FIGS. 1 and 2 a machine constructed in accordance with this invention. It is mounted on a frame having upright side members 1 and 2 suitably mounted at their lower ends on a foundation 3 and having suitable cross members interconnecting the side members as shown at 4 and 5, respectively. It will be understood that the details of this frame form no part of this invention and may be varied considerably.

Mounted in any suitable fashion, preferably within an opening 6 in the foundation 3 is a platform 7. On this the lower end of a form 8 is adapted to rest. This form has an end wall or plate 9 therein adjacent its lower end. This plate has a plurality of openings 10 therein in register with and of the same size as openings to be formed in the conduit which the machine of this invention is adapted to make in the form 8. The platform 7 may be movable so as to remove the form from its working position in the machine after the forming of a conduit therein. The platform 7 may have an opening 11 registering with the bottom end of the form. In accordance with this invention the inside of the form at the corners is rounded as at 8a. The rounded inner surface may be provided in any convenient way, such as, for example, the filleted construction illustrated.

Above the form 8 there is provided within the frame previously mentioned a guide and slide "arrangement. The guide includes a pair of elongated rods 12 secured at their upper ends to the cross member 5 and at their "lower ends to rigid supports 13 extending inwardly from the uprights 1 and 2 toward the central portion of the frame but terminating short of each other.

The slide above mentioned comprises a cross head which may embody a gear box .14. It has openings adapted to embrace the elongated rods 12 and guide the gear box as it slides upwardly and downwardly along such rods. Suspended from the gear box 14 and slidable upwardly and downwardly therewith for a portion of its travel is a loading platform 15. The loading platform is connected to the gear box 14 by means of suspension rods 16 slidable with respect to the gear box at their upper ends and secured to the platform 15 at their lower ends by any suitable means such as the nuts 17 illus trated. Downward movement of the rods 16 with respect to the gear box is limited by the nuts .17 on their upper ends. The loading platform 15 when in its lowermost position rests on top of the form 8 and provides the upper end wall thereof. It has openings 18 axially aligned with the openings 1th in the lower end of the member 9 of the form. On its upper surface the platform 15 is provided with an upwardly extending flange 19 forming a shallow hopper into which cement mix to be loaded into the form 8 may be emptied by a suitable conveyor mechanism 20. This conveyor mechanism may be operated in any suitable manner and the details thereof will not be here discussed.

Carried by the gear box 14 is a set of gears generally indicated at 21 which is adapted to cause rotation of all of a plurality of shafts 22 extending downwardly there from. These shafts carry on their lower ends a plurality of packer heads 23 which may be all constructed as hereinafter more specifically described. The shafts 2.2 are mounted in the gear box 14 so as to be supported against endwise movement by suitable means such as the collars 24 and 25, so that the shafts 2.2 and packer heads 23 move upwardly and downwardly with the gear box 14. As the gear box 14 moves downwardly, the downward motion of the platform 15 therewith is arrested when the platform comes into engagement with the upper end of the mold 8. Thereafter the gear box moves downwardly while the suspension rods 16 and the platform 15 remain stationary as more fully illustrated in FIG. 2.

It may be very The upward and downward movement of the gear box 14 and its associated parts is controlled by means of suitable mechanism such as, for example, the two cables 26 and 27 secured to the opposite lateral extensions 28 and 29 on the gear box by any suitable means such as the eye bolts 30 and 31, respectively. These cables 26 and 27 pass upwardly over a pair of sheaves 32 and 33, respectively, rotatably mounted on the upper end of the frame and so disposed as to direct the two cables toward a suitable hitch 34 to which they are attached and through which the pull on the two cables may be balanced the one against the other. The hitch 34 may then be secured to a single cable or other operating means so that a single operating means will operate to cause the upward and downward movement of the gear box 14 and its associated parts.

The driving mechanism for driving the packer heads 23 is primarily characterized by its ability to rotate all of the packer heads simultaneously and to rotate them while the gear box 14 is being moved upwardly and downwardly. Preferably, in accordance with this invention it is also characterized by its ability to rotate all of the packer heads simultaneously in one direction and the gear arrangement 21 is adapted to accomplish this result. This gear arrangement employs a driving shaft 35 which has a splined engagement within a pinion 36 rotatably mounted on the upper support of the frame so that the shaft 35 may slide upwardly and downwardly with respect to the frame as the gear box 14 moves upwardly and downwardly, and at the same time be constantly in driving engagement with the pinion 36. The pinion 36 in turn is driven by a driving pinion 37. Pinion 37 is driven from a suitable source such as a motor 38 mounted on the cross member 4 of the frame and connected to the shaft carrying the pinion 37 by any suitable means such as a belt 39.

One of the shafts 22 carrying a packer head may be a downward extension of the driving shaft 35. In the case of a group of nine packer heads arranged as shown in FIG. 5, the shaft 35 preferably would be arranged to carry the central packer head.

As shown more clearly in FIGS. 3 and 4 taken with FIG. 1, the shaft 35 has a driving gear 40 fixedly mounted thereon within the upper portion of the gear box 14. The gear 40 is shown in driving engagement with a pair of idler gears 41 on two of the driven shafts 42 which are located closest to the driving shaft 35 and which may be integral with two of the shafts 22. The idlers 41 will, of course, be driven in a direction of rotation opposite to that of the shaft 35. These idlers 41 are in turn meshed with driven gears 43 keyed to the driven shafts to which they are most closely adjacent. These last driven shafts may also be integral with corresponding shafts 22. When gears 43 are driven they will rotate those shafts, and this rotation will be in the same direction as the direction of rotation of the driving shaft 35.

One of the shafts on which the driven gears 43 are carried is provided, at a position longitudinally spaced from the gear 43, with a driving gear 44 keyed thereto and rotating therewith. Gear 44 is in engagement with an idler gear cluster carried on the driving shaft 35 or another conveniently located shaft, the gear 44 being in engagement with the gear 45 of this idler gear cluster. Inasmuch as the gears 44 are carried on shafts rotating in the same direction as the shaft 35, the idler igear cluster will be rotated in the direction opposite to that of the driving shaft 35. Another gear 46 of the idler gear cluster, fixedly carried on the gear 45 so as to rotate therewith, is in mesh with a plurality of driven gears 47 fixedly mounted on each of the remaining shafts 22. Thus it will be seen that each of these remaining shafts 22 will be driven in the same direction as the driving shaft 35 and as the other driven shafts 22 on which the gears 43 are carried. The result will be the driving of all of the packer heads in the same direction simul taneously.

Referring now more in detail to the structure of the packer head as illustrated in FIGS. 6 to 9, inclusive, it will be seen that the shaft on which such head is mounted is provided at its lower end with a tapered portion 48. The tapered portion 48 is adapted to receive a hub 49 having a tapered axially extending opening therein fitting the tapered shaft end 48. Adjacent its upper end this hub 49 has a portion 50 of an outer diameter substantially that of the hole to be formed in the conduit by this packer head and of circular cross-section. This hub is also formed with a downwardly facing shoulder 51 formed on a plane at right angles to the axis of the hub and adapted to receive the upper end of a troweling tubular member or sleeve 52. The sleeve 52 likewise has its upper end formed in a plane at right angles to its axis and has its outer diameter the same as the outer diameter it] of the hub 49. In addition, the hub 49 has a portion 53 which extends into the upper end of the tubular member 52 and serves to center the same on the hub so that when the tubular member 52 is tightly clamped against the shoulder 51 it will be centered on the hub 49 and axially aligned with this hub. When the hub in turn is forced onto the tapered end 48 of the shaft 22 both the hub and the tubular member 52 will be concentric with and axially aligned with the shaft 22.

In order to secure the hub 49 on the tapered end of the shaft 22 and at the same time secure the tubular member 52 on the hub 49, there is provided a clamping mechanism. This includes an end plug 54 having a flange part 55 hearing against that end of the tubular member 52 most remote from the hub 49, and a part of smaller diameter 56 fitting within the said end portion of the tubular member 52. The clamping mechanism also includes a bolt or capscrew 57 having its head bearing against and itself extending through the nose plug 54 and up through the tubular member 52 to threaded engagement with a threaded opening in the end of the shaft 22. It will readily be seen that by tightening this bolt member 57 the tubular member 52 will be tightened against the hub 49 and rigidly secured thereto, and the hub 49 will in turn be tightened upon the tapered end 48 and rigidly secured thereto.

In this modification the packer or slinger section of the packer head is provided by means of a packer element 58 mounted on the upper end of the hub 49 and having a maximum outer dimension substantially equal to the outer diameter of the hub at the portion 50 thereof. This packer element 58 is provided with two lobes, one on each of the two opposite sides of the shaft 22, and is held against r0- tation with respect to the hub 49 by means of dowel pins 59 or the like engaged in correspondingly positioned dowel pin holes in the upper surface of the hub 49 and in the lower surface of the slinger or packer element 58. At its upper end the slinger or packer element 58 is preferably provided with additional dowel holes 60 to receive dowel pins carried on an upper protector plate 61.

In order to protect the shaft 22 from being excessively worn just above the slinger 58, this shaft is slightly re duced in diameter from a position several inches above the slinger 58 in a direction toward its end, leaving a downwardly facing shoulder 62 thereon, and a sleeve 63 is carried on the shaft and gripped between the shoulder 62 and the upper face of the protector plate 61 when the parts are mounted on the shaft as illustrated. This not only holds the sleeve 63 in place against the shoulder 62 but serves to hold the plate 61 in engagement with the slinger element 58 and this element in turn in engagement with the upper end of the hub 49.

The modification just described is especially adapted for use with a tubular member 52 and a slinger element 58 formed of ceramic such as porcelain or the like which, being extremely hard, is highly resistant to wear in the forming operation and has been found to outlast many metal elements employed for the same purpose. However, such procelain elements are expensive and dimcult to manufacture. They are also highly susceptible to being chipped on thei corners and the construction just described protects them against such chipping. Otherwise they could not be employed because of the chipping of the corners that would result in very short usage. This protection of the edges of the tubular element 52 and the slinger element 58 is provided by means of the portion 56 of the hub which, as above stated, is of the same external diameter as the outer diameter of the tubular member 52 and hence protects its upper edge from being chipped, the lower end edges of this tubular member being protected from being chipped by the overlying flange 55 of the nose plug 54, which likewise extends outwardly to provide a continuity with the outer surface of the tubular member 52.

This nose plug is preferably slightly tapered in a downward direction so as to make it easier for the nose portion of this packer head to be moved into the corresponding opening in the end member of the form as will presently be described.

The slinger element 58 is also provided with protection against being chipped on its edges by virtue of the fact that its lower end is in engagement with the upper surface of the hub 49 and its outermost dimension is substantially equal to the outermost dimension of this hub as above explained, so that no chipping impact with the edge of this slinger elemen can take place. The upper edge of this slinger element is protected likewise by the protector plate 61 which is of the same outer contour as the contour of the slinger element 58.

It is noted that the tubular member 52 and the portion 50 of the hub taken together form the troweling section of the packer head and that this troweling section in accordance with this invention is preferably of a length at least equal to twice its diameter. Also, it is noted that the tubular section 52 is provided with a notch in its upper end so as to receive a key member 64 which is carried by the hub 49. This key 64 engages the notch in the tubular member 52 to prevent rotation of the tubular member 52 with respect to the hub 49.

It will be understood that even though the form of the invention illustrated in FIGS. 6 to 9, inclusive, is especially adapted for use with porcelain or other extremely hard though brittle elements to be employed for the main portion of the troweling section and for the slinger section, it may be desirable in some instances to provide these main portions of the troweling section and the slinger section of metal or other material which may be readily employed with this same construction.

However, a similar construction is illustrated in FIGS. 10 to 12, inclusive, which may likewise be employed with metal members as the major portion of the troweling section and as the wear portions of the slinger section. In this construction the shaft 22 is as before provided with a tapered end 48 to receive a hub 4-9 having an upper portion 50 of substantially the same outer diameter as the duct or hole to be formed in the finished conduit. Here likewise a shoulder 51 is provided on the hub 49 to receive the upper end of a tubular member 65 which in this instance is illustrated as formed of metal, preferably some soft metal which may be readily worked and will provide great strength. This tubular member 65 is preferably provided at circumferentially spaced portions around its outer surface with inlaid beads 66 of tungsten carbide or other hard surfacing material. It has been found that by the use of these beads or hard surfacing material at circumferentially spaced points extending longitudinally of the tubular member 65, this tubular member, though of relatively soft material, will be highly resistant to wear occasioned by its rotation in the forming operation. Although not as resistant to Wear as the porcelain tubular member above described, it may be made at less expense Id and without the special equipment required forforming the porcelain tubular member.

A nose plug 67 similar to the nose plug 54 previously described except that it is formed with a somewhat longer taper as sometimes desirable, is shown in the forward end of the tubular member 65. It is secured in place by a bolt 57 which may be in all respects similar to the bolt bearing that number in FIG. 6. The bolt in this instance as well as in FIG. 6 serves to secure the nose plug 67 to the tubular member 65 and the tubular member 65 to the hub 49, and finally the hub 49 onto the tapered end 48 of the shaft 22.

The slinger or packer section above the hub 48 is shown in this instance as being formed of a pair of packer members or slingers 68 each of which is secured to the upper end of the hub 49 by means of a bolt or capscrew 69. The upper ends of these two slinger sections 68 are supported against being pinched inwardly in operation by means of a ring 76 extending entirely around the shaft 22 and having holes therein to receive the upper ends of the bolts or capscrews 69. Thereby both ends of the slinger sections 68 are prevented from moving radially inwardly.

In order to provide against excessive wear which other wise might take place along the outer surfaces of the slingers 68, these outer surfaces are preferably provided with hard surfacing material such as tungsten carbide welded thereto to form an extremely hard surface layer.

It will be seen that in the form just described either slinger section 68 may be replaced without replacing the other and either the slinger section or the troweling section might be replaced without replacing the other in the event that one should wear more than the other. This is true also of the form illustrated in FIGS. 6 to 9, inclusive.

In the form illustrated in FIGS. 6 to 9, inclusive, the slinger or packer is a pressure wing unit having opposed lobes forming its portions of maximum radius which actually determine the gauge of the duct formed in the conduit. However, these portions of maximum radius are not formed on a. short radius of curvature tangent to the curvature of the duct to be formed as in FIG. 11, but of circumferentially short or narrow portions 71 of the same radius as the duct to be formed and coinciding therewith. This presents a substantial and finite surface of the dimension of the duct to be formed so as to dis tribute and minimize the dimension changing effect of wear on this gauge forming part.

The impeller part 72 of this pressure wing unit which moves the mix outwardly in a radial direction is subjected to greatest wear. It has been found that the optimum shape for this surface is cylindrical with a radius approximately the same as that of the gauge forming portions 71 but with its center offset from the center of the portions 4-1 by a little less than one-third of the radius. This curve is extended to approximately a point of tangency with a straight line 73 drawn through the trailing edge of the preceding surface 71.

It has been found that the smooth blending of those external surfaces of this pressure unit radially inwardly from the gauge forming portions, coupled with the portion moving the mix outwardly, formed on the same radius as the duct to be formed, provides a pressuring and troweling action which is highly effective, results in a minimum of wear of the pressure unit, and does not collect and retain mix. When the pressure unit is made of metal, the wear may be greatly reduced and the life of the unit prolonged by originally facing and when worn refacing the surfaces 71 and 72, particularly the latter, with suitable hard facing material such as tungsten carbide.

The troweling skirts 52 and 65 may be greatly increased in effectiveness by providing longitudinally extending, circumferentially spaced ribs or bulges 74 in FIGS. 6 to 9, inclusive, and 75 in FIGS. 10 to 12, inclusive. In the case of the porcelain sleeve of FIGS. 6

to 9, inclusive, these bulges 74 may be integral formed parts of the sleeve, blending at their edges into the smooth outer surface thereof. In the case of a metal sleeve, as in FIGS. to 12, inclusive, they may be outwardly protruding parts of the beads 66 of tungsten carbide, ground or otherwise, formed to blend at their edges into the adjacent surface of the sleeve 65.

Reverting to the over-all machine as illustrated in FIGS. 1 and 2, the operation is as follows:

The form 8 is first put in position on top of the support 7 and the gear box 14 lowered until first the platform rests on top of the form 8 and provides the upper end thereof, and then still further until the packer heads extend a substantial distance through the lower end plate 9 of the form placing the slinger sections in position closely adjacent the bottom plate. Rotation of the packer heads is then begun, all being rotated in one direction as above set forth, and the cement mix feeding mechanism is operated to dump a proper cement mix 71 into the shallow hopper formed by the flange 19 on top of the loading platform 15. This mix is then caused to enter the form 8 by pushing it in through the holes 18 around the rotating shafts 22. As it falls to the bottom of the form and piles up around the upper ends of the packer heads, it will be acted upon by the slinger sections at the upper ends of these packer heads and packed outwardly to begin the formation of the conduit at the lower end of the form. During this initial operation the packer heads are allowed to remain at the same level. In this position they are held against lateral gyration or vibration by engagement with the openings 10 in the end plate of the form. As soon as the concrete at the lower end of the form is sufiiciently packed so as to be firm and compact, upward movement of the packer heads is begun while continuing to feed cement mix into the form. As this upper movement continues the lower ends of the troweling sections will leave the openings 10 in the lower end plate of the form and no longer be held thereby against radial gyrations or vibration. However, by

this time the upper end portions of the troweling sections will already have troweled smooth the interiors of the lower ends of the ducts in the conduit and the lower end portions of these troweling sections will engage such already formed ducts and be held and guided thereby against radial gyrations and vibration. eling sections may be made longer without undesirable effect, it has been found sufiicient if they be made of a length substantially twice that of their diameter, as by the time the lower portions of troweling sections of such length arrive at any given point in the form, the conduits in such form will already have been sufliciently completed and packed by the slinger sections and by the upper portions of the troweling sections so that the lower portions of the troweling sections will be guided and held thereby. During this troweling each head 74 or 75 will act as the edge of a trowel to work and smooth the walls of the duct and leave a very smooth dense surface on such walls.

The completion of the conduit is carried on by continued upward movement of the packer heads while filling the form with additional concrete mix until the form is full and the packer heads arrive at the upper end thereof. At such time the packer heads will be drawn out through the openings 18 in the platform 15. During the entire forming operation the cement mix in the form will circulate around and above the pressure units 58 or 68. The use of forms with rounded corners 11a eliminates most of the turbulence in such circulation and produces a conduit of superior quality throughout, particularly in the smoothness and denseness of the outer surface. Continued upward movement of the gear box 14 will cause engagement thereof with the nuts 17 on the upper ends of the rods 16, whereupon the platform 15 will be lifted away from the upper end of the form 8.

While the trow- 12 Then the form with the formed conduit therein may be moved out of its operating position by movement of the platform 7 or other appropriate mechanism.

It will thus be seen that means have been provided for carrying out all the objects and advantages sought by this invention.

From the foregoing it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the structure.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

The invention having been described, what is claimed l. A conduit forming machine comprising a form having a plurality of openings in one end thereof, and having its inner surface rounded at the intersections of the side walls of the form, a plurality of packer heads mounted for rotational and axial movement in said form and entering and leaving the form through said openings respectively, means mounting said heads for such rotational and axial movement, and driving means connected to said mounting means and including means for rotating all of said heads simultaneously in one rotational direction and means for moving them along their rotational axes to form slurry in the mold into a multiholed conduit.

2. In a multiduct conduit forming machine of the type having a form with aligned correspondingly positioned openings in its opposite ends, each pair of aligned openings being of substantially the diameter of one of the ducts to be formed in the conduit and positioned to register with the ends of such duct when formed, a plurality of packer heads, one for each of said pairs of openings and each head having a slinger section and a troweling section in axial alignment with each other, each of said packer heads being of a maximum over-all diameter normal to its axis to pass through one of said pairs of openings when in axial alignment therewith, and means mount ing said heads for simultaneous rotational movement about their respective axes and longitudinal movement from positions partly within the respective openings in one end of said form through the respective openings in the other end of said form with said slinger sections in advance of said troweling sections, the improvement which comprises said form having all its inner corners rounded, and said troweling sections having longitudinally extending outer surface portions of slightly greater effective radius than the largest effective radius portions of said slinger sections.

3. In a multi-duct conduit forming machine a packer head and mounting assembly comprising a shaft mounted for rotational and longitudinal movement with respect to its axis and having its exterior surface tapered toward and adjacent one end, a slinger section non-rotatably carried on said shaft adjacent said end, a hub in taper fitted engagement with said tapered exterior on the shaft between said slinger section and the end of the shaft and having a sleeve aligning surface coaxial with said taper fitted engagement with the shaft, a tubular sleeve of substantially uniform wall thickness detachably mounted on said hub in aligned engagement with said aligning surface and in axial alignment therewith, and means clamping said tubular sleeve rigidly to said hub in said position, said last-mentioned means including means bridging the opening through said sleeve at a position spaced from said hub, and a releasable tension of said shaft.

References Cited in the file of this patent UNITED STATES PATENTS Richardson Oct. 30, 1888 McNeal et a1. Apr. 23, 1889 Kiel berg Jan. 30, 1906 Keil Oct. 22, 1907 Schenk et a1. Oct. 24, 1911 Schenk et a1 .Nov. 27, 1917 Roosa Apr. 12, 1921 14 Steward June 13, 1922 Scott Sept. 25, 1923 McDonough Aug. 8, 1933 La Due Nov. 28, 1933 Almquist Aug. 28, '1934 ORahill-y Nov. 12, 1940 Schmidt Oct. 10, 1950 Esc-henrbrenner June 16, 1953 Halston June 26, 1956 FOREIGN PATENTS Great Britain Nov. 8, 1949 Great Britain July 9, 1952

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