US3913466A

US3913466A - Apparatus for manufacturing boxes

Info

Publication number: US3913466A
Application number: US450992A
Authority: US
Inventors: Oldrich Bayer; Josef Snasel; Jiri Premyslovsky
Original assignee: Svit np
Current assignee: Svit np
Priority date: 1974-03-14
Filing date: 1974-03-14
Publication date: 1975-10-21
Anticipated expiration: 1992-10-21

Abstract

Pre-cut blanks are folded and formed by apparatus including a form frame and a plunger which is adapted to shove the blank through the form frame simultaneously folding its marginal edges. The form frame includes swingable plates which are adapted to fold-in selected marginal edges of the blank which are provided with shaped projections adapted to lock cooperatively with slots made in their adjacent marginal edges thereby forming a selflocking ready-made box. The swingable plates are connected by adjustable and removable linkage to the plunger to effect swinging of the plate outwardly of the form frame on the inward movement of the plunger and to swing the plate inwardly of the frame an outwart movement of the plunger. The linkage enables the adjustment of the plunger stroke and the swinging of the plate to be made with respect to different sized blanks so as to enable the manufacture of different boxes on the same apparatus.

Description

United States Patent 1 1 Bayer et a1.

[4 Oct. 21, 1975 I APPARATUS FOR MANUFACTURING BOXES [73] Assignee: SVIT, narodni podnik, Gottwaldov,

Czechoslovakia 22 Filed: Mar. 14, 1974 21 Appl. No.: 450,992

[52] US. Cl. 93/51 HW; 93/53 LE [51] Int. Cl. B3113 1/48 [58] Field of Search 93/51 HW, 51 R, 47,51 M,

93/53 BF, 53 LF Primary Examiner-Roy Lake Assistant ExaminerJames F. Coan [57] ABSTRACT Pre-cut blanks are folded and formed by apparatus including a form frame and a plunger which is adapted to shove the blank through the form frame simultaneously folding its marginal edges. The form frame includes swingable plates which are adapted to fold-in selected marginal edges of the blank which are provided with shaped projections adapted to lock cooperatively with slots made in their adjacent marginal edges thereby forming a self-locking ready-made box. The swingable plates are connected by adjustable and removable linkage to the plunger to effect swinging of the plate outwardly of the form frame on the inward movement of the plunger and to swing the plate inwardly of the frame an outwart movement of the plunger. The linkage enables the adjustment of the plunger stroke and the swinging of the plate to be made with respect to different sized blanks so as to enable the manufacture of different boxes on the same apparatus.

6 Claims, 6 Drawing Figures US. Patent Oct. 21, 1975 Sheet10f3 3,913,466

FIG. 2

U.S. Patent Oct. 21, 1975 Sheet20f3 3,913,466

US. Patent Oct. 21, 1975 Sheet 3 of3 3,913,466

APPARATUS FOR MANUFACTURING BOXES BACKGROUND OF INVENTION The present invention relates toapparatus for forming self-locking boxes from pre-cut blanks and particularly to an improved mechanism for folding-in and locking the marginal edges of the box, which apparatus is capable of adjustment to the formation of boxes of different sizes.

In general apparatus for folding and forming pre-cut blanks includes a cooperating form frame adapted to the size of the box to be formed and a plunger adapted to shove the blank through the frame whereby the marginal edges of the blank are folded. The form frame includes swingable plates which are adapted to fold-in and lock selected marginal edges of the blank after initial folding of the blank has taken place. The blank is provided with shaped projections along these marginal edges which are adapted to lodge within and lock in cooperating slots made in the adjacent marginal edges of the blank. In this manner self-locking, ready-made and completely set-up box is formed without the use of staples or adhesive materials.

Known machines for manufacturing boxes in accordance with the description above are constructed to produce box halves (i.e., box bottoms or box tops) having a fixed single size. These machines are particularly limited to the formation of box halves having a single height for its marginal edges. In order to manufacture box bottoms or tops having a different height or size, it was necessary to provide separate machines designed specially for thes different dimensions. On the other hand, attempts were made to adapt existing machines so that they can be adjusted to varying dimensions of boxes. This was usually done by employing complicated complex adjusting elements for the plunger and the form frame. In general it required extensive and tedious adjustment of these elements, by specialized servicemen to affect the adjustment. Furthermore, the adjustability of any one existing machine of the known type was only over a narrow range and therefore a single machine could not be made to provide economical and simple adjustment for a wide variety of boxes.

It is an object of the present invention to provide apparatus for the folding and forming of pre-cut box blanks into box halves which overcomes the disadvantages of the prior art devices.

It is a further object of the present invention to provide apparatus for the formation of ready-made boxes which is adjustable in an easy and simple manner for varying dimensions.

It is a further object of the present invention to provide apparatus for the formation of boxes having locked-in marginal edges which apparatus is easily adaptable and adjustable for varying heights of marginal edge.

It is a further object of the present invention to provide a cooperating pre-cut box blank for use in the apparatus mentioned above.

The foregoing objects, other objects and advantages, will be clearly seen from the description of the present invention, following.

SUMMARY OF THE INVENTION According to the present invention apparatus for manufacturing boxes and the like from pre-cut blanks is provided comprising a cooperating form frame and a plunger which is reciprocatingly moved into and out of the frame to thereby fold over the marginal edges of the blank. The frame is provided with at least one locking plate swingable about its longitudinal axis on the passage of the plunger into and out of the space formed by the frame to fold-in the marginal edge of the blank so as to cause the marginal edge to lock into fixed engagement with the adjacent marginal edges of the blank. The means for swinging the locking plate comprises a pinion gear secured to the axis of the locking plate which meshes with a swingable segment gear. A rod is adjustably connected to the means for reciprocating the plunger to affect swinging of the plate outwardly ofthe frame on the inward movement of the plunger and to swing the plate inwardly of the frame on the outward movement of the plunger. In this manner the locking plate is movable into engagement with the marginal edge of the pre-cut blank after it is initially folded by the plunger and after the plunger has been removed from the form frame. The adjustable connection between the rod and the reciprocating plunger enables the stroke of the plunger with respect to the form frame to be easily varied and in this manner accommodation can be made for different heights of the marginal edges of the box being formed.

Preferably the means for connecting the rod to the plunger comprises a clamp through which the rod freely extends. Adjustably stop means are located at the outer end of the rod and means for resiliently biasing the segment gear is provided to normally urge the rod in one direction and permit the rod to freely move in the opposite direction.

The segment gear is resiliently biased by a spring and is limited in its movement by the provision of at least one fixed stop member. The connection of the rod is further effected by mounting the clamp on an arm fixed to a piston rod which reciprocates the plunger member.

Further according to the present invention the gear mechanisms for operating the locking plates are mounted directly on the form frame and the connecting rod linking this mechanism to the plunger is easily removable therefrom. In this manner the apparatus according to the present invention permits the easy removal of the form frame and its replacement with another form frame of a different size so that boxes having other dimensions may also be made on basically the same machine. A single machine may be equipped with several complete forming frames so that on initiation of the production of any type and size of box the machine operator himself, without the help of any technical or specialized Serviceman, can change the fomi frame. Thereafter merely reattaching the connecting rod and making the proper adjustment for the stroke of the plunger.

Full details of the present invention are set forth in the following description of an illustrative embodiment and are shown in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a side-elevational view of a box forming machine employing the present invention, in which the plunger has been removed in order to enable viewing of the interior elements,

FIG. 2 is a plan view of the machine shown in FIG.

FIG. 3 is an enlarged plan view of a portion of the device shown in FIG. 2 illustrating the details of the locking plate and its linkage to the plunger,

FIGS. 4, 5, and 6 are sequential views of a box blank being folded into a box half in accordance with the steps employed in the present apparatus.

DESCRIPTION OF THE INVENTION Turning to FIGS. 1 and 2, the box forming machine of the present invention comprises a base 1 which is generally horizontally disposed and on which a plurality of bolts 2 fastens a vertical supporting standard 3. Carried on top of the vertical standard 3 is a T-shaped housing 4 in which is contained a pneumatic motor arranged with its axis parallel to the plane of the base 1. In the central portion of the housing 4 there is located a double acting pneumatic motor comprising a cylinder having inlets/outlets 5 and 6 and a piston having a piston rod 7 extending axially outward therefrom. The pneumatic motor is conventional in form and is connected to a source of air under pressure with suitable valving so as to affect the reciprocating movement of the piston rod 7 under selected predetermined conditions. The pneumatic motor may as will be obvious be replaced by a hydraulic motor of similar construction.

Attached to the end of the piston rod 7 is a U-shaped (horseshoe-shaped) holder 8 which is secured to the piston rod at the center of its transverse member. The holder 8 has a pair of spaced arms depending downwardly toward the base in a vertical plane. The holder 8 is thus movably conjointly with the piston rod 7. The holder is further guided against twisting and is maintained in its line of movement by a pair of guide shafts 9which are freely slidable through the extending arms of 'the T-shaped housing. The shafts 9 extend parallel to each other and to the base 1 and are connected to the corners of the holder member 9. Adjustable stop members1l0, comprising a clamp and a bolt fastener, are located at the free ends of each of the rods 9 and are selectively adjustable so as to limit the stroke of the pistonrod 7. Fixed coaxially at the end of the piston rod 7 is a strut 11 at the end of which the form plunger 12 is fixed.

Extending laterally outward from each of the bottom end of the arms of the holder 8 is an arm 13 on which a clamp 14 is located. The clamp 14 is adjustable and fixed in selected positions along the arm 13 by a bolt or screw 15, which is retained in a threaded bore in the clamp against pressure engagement with the arm 13.

Removably fixed, by bolts 16 to the base 1, transversely of the axis of movement of the plurger 12 and at a point in front of the housing 4 approximately at the extension of the plunger 12, as seen in FIG. 2, is a rectangular forming frame 17. The form frame 17 includes upper and lower longitudinal supporting bands 17a and 17b symmetrically disposed with respect to the axis of the pneumatic motor and spaced apart a vertical distance approximately equal to the dimension of the plunger 12. The form frame 17 is spaced from the base 1 by a pair of legs 170 preferably integral with its vertical sides.

Located at the edge of the bands 17a and 17b, nearest to the pneumatic motor, are a pair of vertical folding slats 18. Located at the edge furthest from the pneumatic motor are a pair of vertical shaping walls 19. The folding slats and shaping wall pairs form a rectangular space through which the plunger 12 is adapted to move and are consequently spaced from each other a horizontal distance approximately equal to the plunger. Arranged between each associated set of folding slats 18 andshaping walls 19 is a'swingable locking plate 20 which extends the full vertical distance between bands I 17a and 17b. Each locking plate is journalled in the band 17a and 1712 by an pin 21 and is shaped so as to move into and out of the box forming space into opposing relationship with the shaping wall 19.

The lower axle pin 21 of each of the locking plates 20 extends through'the lower band 17b and is provided with a fixed circular or pinion gear 22. The pinion gear 22 meshes with a gear segment 23 freely swingable about a pin 24 secured to the lower side of the band 17b. The gear segment 23 is retained on the pin 24 by the use of conventional means such as a cotter pin, clip or the like. The segment gear 23 is provided with a hole 25 in which is anchored one end of a compression spring 26, the other end of which is anchored in a hangar 27 fixed also to the lower surface of the lower band 17b. The spring 26 is arranged so that it normally biases the segment 23 to swing the locking plate 20 outwardly from the interior of the forming space defined by the slats 18 and shaping wall 19, as is shown in FIG. 3. The movement of each of the segments 23 is limited by a stop pin 28 also secured to the lower surface of the band 27.

From the foregoing it will be seen that all of the associated mechanism of the form frame 17, namely, the slat and

spacing walls

18 and 19, the locking plates and the gear mechanism for swinging the locking plates, are

provided as a unitary assembly which can easily be removed from the base 1 and which is not connected structurally or functionally to the plunger 12 or the means for reciprocating the plunger. In this manner form frames 17 and the associates mechanisms can be provided for different sized and dimensioned boxes easilyaccommodated on the single machine.

Extending from the lower face of each of the gear segments 23 is a pin 29 over which the eye end of a pull rod 30 is hung. The pull rod 30 passes outside of the space formed by the slats l8 and shaping walls 19 parallel to the axis of the piston rod 7 freely through a hole formed in the adjustable clamps 14 which are located on the laterally outwardly extending arms 13 fixed to the holder 8. An adjustable stop bracket 31 is fixed to the free end of the pull rods 30 on the opposite side of the clamp 14. A shock absorber 32 such as a resilient pad, belleville spring or the like, is located between each of the adjustable stops 31 and its associated clamp 14. In this manner the pull rod 30 is freely movable through its associated clamp 14 in one direction but is limited in movement by the stop bracket 31 in the opposite direction. The shock absorbers 32 are adapted to absorb any shock created by the engagement of the stop bracket 31 against the clamp 14. Adjustment of the stop bracket 31 along the rod 30 defines the movement of the swingable gearsegments 23 with respect to the movement of the piston rod 7. Preferably this position of the stop bracket 31 ismade so that the gear segment 23 is swung into a position rotating the locking plates 20 into the forming space, as seen in FIG. 2, when the plunger 12 and consequently the piston rod 7 is withdrawn outwardly from the forming space defined by the form frame 17. I

The form frame 17 is provided with means for holding a pre-cut andpre-scored blank 33 comprising a pair of vertical U-shaped guides 34. The guides34 are pro vided with a sensor 35 such as a microswitch or the like. The blanks are held, in a not shown supply source above the machine and are adapted to be fed in a vertical manner into the guides 34 and held in a plane perpendicular to the axis of movement of the plunger 12. The means for feeding such blanks is conventional and is not described hereinas the same will be obvious to those skilled in this art.

As seen in greater detail in FIG. 4, 5, and 6, each of the blanks 33 is provided with previously cut and scored edges which are intended to be folded at least twice to form longitudinal sides 36 havinginterior liners 37 and transverse ends 38 having a similar internal liner 39. The marginal edge forming the internal end liner 39 are each provided with projections 40 which are adapted to fit into a slot 41 formed by tapering or cutting the ends of the liner 37 at the bias. As seen in FIG. 6, this folding and locking of the projection40 produces a fully set up box reinforced along its sides, which is securely held in this construction without the use of any staples or reinforcements or adhesives. [t is the function of the present apparatus, and in particular, the locking plate 20 described earlier, to fold the marginal liner edge 39 and cause the locking of the projections 40 to form the box seen in FIG. 6. i

The machine in accordance with the present invention operates in the following manner: e

The not illustrated feed device feeds the' blanks 33 in their vertical position above the guides 34 and under the effect of gravity individual blank 33 is caused to fall within the guide 34 until it sits on the detecting sensors of the sensing device 35. The sensing device 35 creates an electrical pulse signal fed to the source of air or fluid under pressure or to its appropriate valving mechanism so that pressurized air or fluidis fed to the inlet 5 behind the piston of the pneumatic or hydraulic motor. The piston consequently. ,moves the piston rod '7,,the holder 8 and the strut 11 on which the plunger 12 is mounted in its outward direction toward the form frame 17. The blank 33 is thus caused to be pushed by the plunger 12 into the space formed by the form frame 17. The longitudinal sides 36 of the blank 33 are folded over the corresponding edges of the form frame 17. These corresponding edges are provided with tapered surfaces such as those formed on the folding slat 18 whereby the sides 36 may be more easily folded into their required position. The transverse ends of 38 of the blank 33 are simultaneously folded the tapered edges of the folding slats 18 to form the shape indicated in the dash dotted lines of FIG. 3.

The forward movement of the plunger 12 is affected by the activation of the piston rod 7. The piston rod 7 carries with it simultaneously the U-shaped holder 8 and the laterally extending arms 13 on which the clamps 14 are located. These latter elements move simultaneously with the plunger 12 toward the form frame 17. Through this movement, the abutment stops 31 and their associated shock absorbers 32 remain in engagement with the clamps 14 because the biasing acting of the springs 26 cause the gear segments 23 to pull the pull rods 30 forwardly in the direction of the movement of plunger 12. Thus the gear segments 23 are allowed to swing about their pins 24 causing themeshing pinions 22 to swing the locking plates open or outwardly from the interior of the form space defined by the shaping walls 19. The swinging locking plates 20 6 open and swing outwardly into'the position shown in FIG. 3 prior to the arrival of. the plunger i12'1and the blank- 33 in the form: frame 17. The locking plates ,20 are maintained in-their outward position by the pulling or biasing forceof the spring 26 during the time the plunger 12 is moved by the piston rod '17 in itsentire strokethrough the form'frame 17.*During the latter portion of the stroke of thep'lunger 12 the clamps 14 slide freely over the pull rods 30 being removed from engagement to the shock absorbers 32 while simultaneously the gear segment 23 abuts against the stop pin 28 which limits the movement of both segment 23 and the pull rod 30. v I

- 0n the pistons 7 making its full stroke the plunger 12 reaches its forward dead center position and stops. In this position the marginal edge portions 39 of the transverse ends 38 extend as seeniin FIG. 2 perpendicular to the face of the box blank 33; Thereafter the plunger 12 starts its backward movement by appropriately shifting the pressurized media to the pneumatic or hydraulic motor. The plunger 12 retracts from frame 17 leaving the box with its not yet folded marginal edges 39 remaining inside theform frame. During this backward movement of the plunger 12 the clamps 14 move freely over the pull rods 30 until they abutagainst the shock absorber members 32 and the stop brackets 31. The shock absorbers 32 act to absorb and moderate the shock of this engagement? The continuing backward movement of the plunger12 pulls the pull rod 30 with it causing the gear segments 23 to be pivoted about its pivot pin 24 rotating the pinion gears 22 counter to the bias of 'the'spring 26 causing the locking plates 20j't o moveinwardly into the space formed'by the form frame which engage the marginal edges 39'of the blank and fold over and push these margins 39 onto the transverse edges 38 of the'box. The locking plates 20 "further cause the projections 40 on these'marginal edges 39 to fit securely into the slots 41 and thus lock in place guaranteeing both theproper shape of thebox and the proper engagement to set up a pre -formed reinforced box structure. The completed box is then pushed from the interior of the form frame 17 during the cycle'in which the next blank 33 is itself formed into the box as described above.

,; In setting up the ap'paratus the abutment member 31 is seton the rod 30 so that it and the shock absorber 32 abut against the clamp 14 when the piston rod 7 is I retracted to its rearmost inoperative rest position as indicated in FIG. This reduces play between i the bracket 31 and the clamp 14. Further this positioninsures that the locking plate 20 is swung out of the interior of the forms at or about the time the plunger reaches the position of the front slats 18 and on the return stroke the locking plates 20 are swung back into the form 17 not before the plunger reached the same position. This avoids interference of the locking plates 20 with the plunger 12 during its operative cycle. Preferably the blank as seen in FIG. 4 is provided with

prefolded edges

36 and 37 which are adhered together by a suitable adhesive. Thus the longitudinal edges are merely folded into their perpendicular position by the movement of the plunger 12.

When it is desired to employ the present apparatus for manufacturing boxes of a different size, particularly boxes having a different height to their marginal edges, the entire form frame 17 is removed and replaced with another assembly of a form frame 17. The machine may -be'equipped with a set of several different form frames-.17 corresponding to a variety of standard box sizes. lAS noted earlier each of the form frame assemblies has its own locking plate 20, gear segments 23, pull rods 30, and so on. Each of the form frames in the set is formed with corresponding holes through which the bolts 16 are placed so that it may be secured to the table. l. When changing the form frame, the pull rods are passed through the holesof the clamps 14 which are then adjustably mounted on the arms 13 so that the pullrods 30 remain parallel to the piston'rod 7. This adjustment may be necessary due to the difference in length of the box being formed. Next the abutment stops31 and their absorbers 32 are adjusted on the rods 30 according to the height of the box being produced. This adjustment ismade so that the closing movement of the.locking plate 20 follows after the return movement of the pulunger l8 r eachesatv least the level of the folding slats 18 so thatthe inward movement of the plates 2 will not interfere with the plunger 12. Adjustment of thestops 10 on the guide shafts 9 which stabilize the movement of .the holder,8 are also made in order to limit the forward. movement of the plunger 12 to correspond to the depth of the form frame 17.

, It will .be seen from the foregoing that a simple machine is provided with apparatus by which various sized boxes can be folded and formed. In accordance with ,the present invention the entire form frame and locking platesare designed as a unitary assembly which aree'asily removed and replaced with another form frame corresponding to the box to be formed. In making this exchange it is only necessary to make a simple adjustment of the abutting stop 31 on thepull rods 30 and at most a simultaneous adjustment on a similar abutment member 10 on the guide shaft 9. These adjustments can be made by an unskilled machine operator and do not require extensive or complex adjustment of the machincry in any other respect.

Various changes and modifications will be obvious to jthos e skilled in the present art. It is intended therefore that the present disclosure be taken as illustrative only of the present invention and not as limiting of its scope.

' What is claimed is:

1. Apparatus for manufacturing boxes'and the like from pre-cut blanks comprising a cooperating form cured to the axis of said locking plate, a segment gear meshing with said pinion, a rod pivotally linked to said segment gear and adjustably connected to said means for reciprocating said plunger to effect swinging of the plate outwardly of said frame on inward movement of said plunger and to permit said plate to swing inwardly of said frameon outward-movement of said plunger, said adjustable connection of said rod to said means for reciprocating said plunger comprising a clamp, said rod extending. freely through said clamp and adjustable stop means locatedvon the outer end of said rod, and means for resiliently biasing said segment gear to urge said rod to normally permit engagement of the adjustable stop means against said clamp.

I 2. The apparatus according to claim 1, including a base on which said plunger and form frame are supported, said form frame being removably mounted to said base. i 3. The apparatus according to claim 1, including spring means resiliently biasing said segment gear and stop means limiting the movement of said segment gear.

4. Apparatus for manufacturing boxes and the like from pre-cut blanks comprising a cooperating form frame and plunger, means for reciprocating said plunger into and out of said frame to fold said blank, said means for reciprocating said plunger comprising a piston and cylinder, said plunger being connected to said piston, a bracket attached to said piston and conjointly movable therewith, said frame having at least one locking plate adapted to swing on passage of said plunger into and out of said frame to fold-in the edge of said blank, and means for swinging said locking plate comprising a pinion gear secured to the axis of said locking plate, a segment gear meshing with said pinion,

a rod pivotally linked to said segment gear and adjustably connected to said means for reciprocating said plunger to effect swinging of the plate outwardly of said frame on inward movement of said plunger and to permit said plate to swing inwardly of said frame on outward movement of said plunger, said means for connecting said rod being adjustably secured to said bracket. g r

5. The apparatus according to claim 4, wherein said piston and cylinder is located in the housing and said bracket is'provided with guideshaft extending through said housing to stabilized the movable piston.

6. The apparatus according to claim 4, including a base on which said plunger and form'are supported, said form frame being removably mounted to said base.

Claims

1. Apparatus for manufacturing boxes and the like from pre-cut blanks comprising a cooperating form frame and plunger, means for reciprocating said plunger into and out of said frame to fold said blank, said frame having at least one locking plate adapted to swing on passage of said plunger into and out of said frame to fold-in the edge of said blank, and means for swinging said locking plate comprising a pinion gear secured to the axis of said locking plate, a segment gear meshing with said pinion, a rod pivotally linked to said segment gear and adjustably connected to said means for reciprocating said plunger to effect swinging of the plate outwardly of said frame on inward movement of said plunger and to permit said plate to swing inwardly of said frame on outward movement of said plunger, said adjustable connection of said rod to said means for reciprocating said plunger comprising a clamp, said rod extending freely through said clamp and adjustable stop means located on the outer end of said rod, and means for resiliently biasing said segment gear to urge said rod to normally permit engagement of the adjustable stop means against said clamp.

2. The apparatus according to claim 1, including a base on which said plunger and form frame are supported, said form frame being removably mounted to said base.

3. The apparatus according to claim 1, including spring means resiliently biasing said segment gear and stop means limiting the movement of said segment gear.

4. Apparatus for manufacturing boxes and the like from pre-cut blanks comprising a cooperating form frame and plunger, means for reciprocating said plunger into and out of said frame to fold said blank, said means for reciprocating said plunger comprising a piston and cylinder, said plunger being connected to said piston, a bracket attached to said piston and conjointly movable therewith, said frame having at least one locking plate adapted to swing on passage of said plunger into and out of said frame to fold-in the edge of said blank, and means for swinging said locking plate comprising a pinion gear secured to the axis of said locking plate, a segment gear meshing with said pinion, a rod pivotally linked to said segment gear and adjustably connected to said means for reciprocating said plunger to effect swinging of the plate outwardly of said frame on inward movement of said plunger and to permit said plate to swing inwardly of said frame on outward movement of said plunger, said means for connecting said rod being adjustably secured to said bracket.

5. The apparatus according to claim 4, wherein said piston and cylinder is located in the housing and said bracket is provided with guide shaft extending through said housing to stabilized the movable piston.

6. The apparatus according to claim 4, including a base on which said plunger and form are supported, said form frame being removably mounted to said base.