Mold for producing masonry block with roughened surface

A mold for producing a masonry unit with a roughened texture side surface having a plurality of side walls defining a mold cavity open at its top and bottom, adapted to receive masonry fill material by way of its open top, and to discharge molded fill material in the form of a block of predetermined height by way of its open bottom; and a wedge-shaped lower lip located along the lower edge of at least one of the side walls, and extending into the mold cavity, the lower lip having grooves formed therein which are oriented at an oblique angle to the general direction of movement of concrete fill material through the mold cavity.

BACKGROUND OF THE INVENTION
 U.S. Pat. No. 3,940,229 describes a mold for making concrete masonry units
 with a roughened texture on at least one face. The mold has a wall with an
 inwardly extending lip on the lower edge of the wall. The lip is
 rectangular in profile, and may be solid or serrated to provide
 sawtooth-like projections. As the formed concrete unit is forced out of
 the bottom of the mold, the patent says that the lip produces a scraping
 or tearing action on the adjacent face of the concrete unit, so as to
 produce a roughened surface on it. We have experimented with this type of
 mold, and found that it does produce a roughened surface on the concrete
 unit, but that the face sometimes has a slight "shingled" appearance.
 Angelo Lane Incorporated of Carnegie, Pennsylvania has also, for many years
 utilized a similar mold to produce a roughened textured face on concrete
 masonry units. Lane's mold includes a bead of weld material along the
 lower edge of a mold wall. Generally parallel grooves about one quarter
 inch wide are ground into the bead at about half-inch intervals. The
 grooves have been oriented both parallel to the direction of travel of
 material through the mold, and at an angle thereto.
 U.S. Pat. Nos. 5,078,940 and 5,217,630 also describe a mold for making
 concrete masonry units with a roughened texture on at least one face. The
 mold described in these patents also employ an inwardly extending lip on
 the lower edge of at least one wall of the mold. In this case, the lip is
 wedge-shaped in profile. In addition, the mold includes a plurality of
 projections above the lip on the same wall and a mesh extending upwardly
 from the lip generally parallel to the wall and spaced inwardly from the
 wall. The projections and the mesh are adapted to hold a portion of the
 concrete fill material against the wall as the formed concrete unit is
 forced out of the bottom of the mold. As described in these patents, the
 concrete material held against the mold wall by the projections and the
 mesh is sheared from the concrete material forced out of the mold, thus
 forming a roughened surface on the concrete unit forced from the mold. We
 believe that molds of this design, although without the mesh, have been
 commercialized under trademark Softsplit. We do not have any direct
 experience with the Softsplit molds, but understand from those who have
 used them, that the process must be occasionally interrupted to clean out
 the material that agglomerates around the projections. This is not
 necessarily an easy cleaning process. It depends upon how accessible the
 mold face is to the machine operator. In many of the commonly used
 concrete block machines, the mold faces are relatively difficult to get
 at, and safety dictates that precautions such as machine lockouts and the
 like be used when the cleaning process is undertaken. Unlike this Sofsplit
 style mold, the mold of the '229 style is self-cleaning. The small amount
 of material that remains loosely adhered to the lipped mold wall after the
 mold is stripped is knocked clear of the wall when the next machine pallet
 is placed against the mold bottom.
 U.S. Pat. No. 5,879,603 describes an improvement to the '229 style mold.
 The '603 patent describes a mold with a wedge-shaped lower lip and an
 opposed upper lip spaced apart from the lower lip by the distance defining
 the height of the concrete unit to be produced. The mold acts in a similar
 fashion to the '229 style mold, but produces less "shingling" effect on
 the roughened face, and is also self-cleaning in the same fashion: the
 concrete material that loosely adheres to the mold wall above the lower
 lip is knocked off the wall when the next pallet is brought into place
 beneath the mold.
 SUMMARY OF THE INVENTION
 The present invention is another improvement on the '229 style mold. We
 have discovered that we can produce a satisfactory roughened surface on a
 concrete unit by forming grooves in a wedge-shaped lower lip. One
 embodiment described in the '229 patent includes grooves in the lower lip.
 The grooves are oriented so that they run in the same direction that the
 material moves through the mold. In the present invention, the grooves are
 oriented at an angle to the direction of travel of material. We do not
 know exactly how these angled grooves are operating within the process,
 but the units produced seem to have less "shingling" than the units
 produced by the solid or serrated lips of the '229 patent, and the mold
 remains self-cleaning.

DETAILED DESCRIPTION OF THE INVENTION
 The invention is a mold for producing a masonry unit or block with a
 roughened texture on at least one of its side surfaces. The invention may
 be used with any number of different types of molds to produce any variety
 of blocks. An example of the mold 10 can be seen in FIG. 1. The mold may
 have a single cavity 12 or, as can be seen in FIG. 1, multiple cavities.
 Side walls 14, 16, 18, 20 define the mold cavity 12. The mold is open at
 its top and bottom.
 The mold is adapted by means not shown, but well known to those of ordinary
 skill in the art, to be mounted in a machine for producing concrete
 products, such as blocks, slabs, or pavers, from low slump concrete fill
 material. There are many of these types of machines available. Some of the
 manufacturers of these machines are Besser, Columbia, Fleming, Tiger, KVM,
 Masa, Zenith, and Omag.
 When the mold is mounted in the machine, a pallet 60 is moved into position
 under the mold. The pallet is typically a steel or wooden plate. The mold
 open top allows it to receive concrete fill material up to a predetermined
 level in the cavity. The mold open bottom allows discharge of the molded
 fill material. After the mold is filled, the fill material is compacted by
 vibration and the action of a stripper shoe head plate 40 to a
 predetermined, compacted level corresponding with the finished height of
 the finished block.
 The mold also comprises a lower lip 32 along at least one of the mold side
 walls.
 In the preferred embodiment, the lip 32 is formed along each of the side
 walls 14. The lower lip 32 is located at the bottom of the mold cavity 12
 (FIG. 2), and extends into the cavity.
 The shape of the lip in cross section is preferably a wedge, as best shown
 in FIG. 5. Preferably, the height of the wedge, measured along its back
 wall 20 is about 3/16 inch. Preferably, the depth of the wedge, measured
 along is lower wall 22, is also about 3/16 inch. In this configuration,
 the front face 24 of the lip is oriented at about a 45 degree angle. In
 this preferred configuration, the lip tapers to a relatively thin leading
 edge 28. Other lip profiles, such as rectangular, also work.
 A plurality of grooves 30 are formed in the lower lip. In the preferred
 embodiment, the grooves are parallel to each other, and are oriented at an
 angle a of about 30 degrees from horizontal. They are about 1/16 inch
 wide, and are spaced about 1/2 inch apart along the entire length of the
 lip. The angular orientation of the grooves may vary. They all do not have
 to be parallel. The dimensions and spacing may also vary. The grooves may
 extend fully through the lip from the leading edge 28 to the back wall 20.
 However, in the preferred embodiment of the invention, the grooves are
 formed in the angled wedge face 24 of the lip, and are about 1/16 of an
 inch deep. This creates a serrated outboard edge to the lip, with channels
 running back at an angle along the angled wedge face of the lip from the
 serrated edge of the lip as shown in FIG. 3.
 The lower lip 32 may formed on the side wall 14 by machining. It may also
 be welded to the side wall. Preferably, however, it is releasably attached
 to the side wall by means such as bolts, screws, etc. This arrangement
 allows for relatively easy replacement of the lip, which is important
 because the lip is a wear point in the mold apparatus and may after time
 wear, chip or break.
 The lower lip of the present invention may also be used in combination with
 the upper lip described in U.S. Pat. No. 5,879,603, which is incorporated
 herein by reference.
 To use the invention, a machine pallet 60 is brought into position beneath
 the mold 10, and the mold is filled to a predetermined initial fill level
 with low slump concrete fill material 50. As is known in the art, low
 slump concrete fill generally is composed of aggregate such as sand and
 gravel, cement, and water. It may contain other additives such as color
 pigment.
 Once filled, the mold is vibrated for several seconds, the time necessary
 to ensure the fill is uniformly spread throughout the mold. This vibrating
 may occur in concert with the compressive action of the stripper head 40
 onto the fill 50 in the mold 10. The combined action of the vibration and
 the stripper head lowers the level of the fill to a predetermined,
 compacted level, corresponding with the height of the finished unit.
 The pressure applied by the stripper shoe ranges from about 1,000 to 8,000
 psi and preferably is about 4,000 psi. Once the compression and vibration
 period is over the stripper shoe 40 in combination with the underlying
 pallet 60 acts to strip the blocks from the mold, FIG. 6. The lower lip 32
 acts to scrape, tear, or roll fill material in the region of 50' from the
 remainder of the masonry unit or block at what will become the roughened
 surface 45 of the block. This provides a masonry unit or block 50 having a
 roughened surface 45. The roughened texture produced is more or less
 random in appearance. There may be some shingling, some peaks and valleys,
 and some interspersed aggregate and pock marks.
 Some of the fill material falls onto the pallet 60 as it is scraped off of
 the masonry unit. Some small amount of the material loosely adheres to the
 mold side wall 14. This material is knocked off of the wall 14 when a new
 pallet 60 is brought into place for the next cycle of the machine. Thus,
 the mold is self-cleaning, and it is not necessary to interrupt production
 to clear the mold wall 14 of compacted fill material.
 Other patents which we know of that are related to block forming include
 U.S. Pat. Nos. 5,249,950 and 5,062,610 which are both incorporated herein
 by reference.
 Once the blocks are formed they may be cured through any means known to
 those with skill in the art. Curing mechanisms such as simple air curing,
 autoclaving, steam curing or mist curing are all useful methods of curing
 the block resulting from my invention.
 The above discussions, examples and embodiments illustrated are current
 understanding of the invention, however, since many variations of the
 invention can be made with departing from the spirit and scope of the
 invention, the invention resides wholly in the claims hereafter appended.