U.S. patent application number 13/759511 was filed with the patent office on 2013-06-13 for retaining wall containing wall blocks with weight bearing pads.
The applicant listed for this patent is David M. LaCroix. Invention is credited to David M. LaCroix.
Application Number | 20130149043 13/759511 |
Document ID | / |
Family ID | 40568800 |
Filed Date | 2013-06-13 |
United States Patent
Application |
20130149043 |
Kind Code |
A1 |
LaCroix; David M. |
June 13, 2013 |
RETAINING WALL CONTAINING WALL BLOCKS WITH WEIGHT BEARING PADS
Abstract
A retaining wall having a plurality of courses of retaining wall
blocks including a first upper course and a second lower course.
Each retaining wall block has opposed front and rear faces, opposed
first and second side surfaces, and opposed and substantially
parallel upper and lower surfaces, and at least one weight bearing
pad extends from one of the upper and lower surfaces. The at least
one weight bearing pad extends substantially from the rear face to
the front face of the block. The weight bearing pads are the only
areas of contact between the blocks in the first upper course and
the blocks in the second lower course.
Inventors: |
LaCroix; David M.; (St.
Paul, MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LaCroix; David M. |
St. Paul |
MN |
US |
|
|
Family ID: |
40568800 |
Appl. No.: |
13/759511 |
Filed: |
February 5, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12266951 |
Nov 7, 2008 |
|
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13759511 |
|
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60986483 |
Nov 8, 2007 |
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Current U.S.
Class: |
405/284 |
Current CPC
Class: |
B28B 3/021 20130101;
E02D 29/025 20130101; E04B 2/44 20130101; B28B 7/241 20130101; E02D
29/0266 20130101; E04C 1/395 20130101; B28B 7/0097 20130101 |
Class at
Publication: |
405/284 |
International
Class: |
E02D 29/02 20060101
E02D029/02 |
Claims
1. A retaining wall comprising a plurality of courses of retaining
wall blocks including a first upper course and a second lower
course, each retaining wall block having opposed front and rear
faces, opposed first and second side surfaces, and opposed and
substantially parallel upper and lower surfaces, and at least one
weight bearing pad extending from one of the upper and lower
surfaces, the at least one weight bearing pad extending
substantially from the rear face to the front face of the block,
and the weight bearing pads being the only areas of contact between
the blocks in the first upper course and the blocks in the second
lower course.
2. The retaining wall of claim 1, wherein the weight bearing pads
in the first upper course and the second lower course are
vertically aligned.
3. The retaining wall of claim 1, wherein the weight bearing pads
extend from the lower surfaces.
4. The retaining wall of claim 3, wherein each retaining wall block
comprises two weight bearing pads.
5. The retaining wall of claim 3, wherein each retaining wall block
comprises just two weight bearing pads.
6. The retaining wall of claim 1, wherein each weight bearing pad
is a rectangular prism.
7. The retaining wall of claim 1, wherein each weight bearing pad
has a height of from 1/8 to 1/2 inch (0.3 to 1.3 cm).
8. The retaining wall of claim 1, wherein each weight bearing pad
has a height of from 1/8 to 3/8 inch (0.3 to 1.0 cm).
9. The retaining wall of claim 6, wherein the dimensions of each
weight bearing pad are from 1 to 3 inches (2.5 to 7.6 cm) wide, 7
to 11 inches (17.8 to 27.9 cm) long, and 1/8 to 3/8 inch (0.3 to
1.0 cm) deep.
10. The retaining wall of claim 1, wherein each weight bearing pad
is level.
11. The retaining wall of claim 1, wherein each weight bearing pad
has a slope.
12. A method of making a retaining wall comprising: providing a
plurality of retaining wall blocks, each retaining wall block
having opposed front and rear faces, opposed first and second side
surfaces, and opposed and substantially parallel upper and lower
surfaces, and at least one weight bearing pad extending from one of
the upper and lower surfaces, the at least one weight bearing pad
extending substantially from the rear face to the front face of the
block, and placing the retaining wall blocks into a plurality of
courses including a first upper course and a second lower course,
the weight bearing pads being the only areas of contact between the
blocks in the first upper course and the blocks in the second lower
course.
13. The method of claim 12, wherein the weight bearing pads in the
first upper course and the second lower course are vertically
aligned.
14. The method of claim 12, wherein the weight bearing pads extend
from the lower surfaces.
15. The method of claim 14, wherein each retaining wall block
comprises two weight bearing pads.
16. The method of claim 14, wherein each retaining wall block
comprises just two weight bearing pads.
17. The method of claim 12, wherein each weight bearing pad is a
rectangular prism.
18. The method of claim 12, wherein each weight bearing pad has a
height of from 1/8 to 1/2 inch (0.3 to 1.3 cm).
19. The method of claim 12, wherein each weight bearing pad has a
height of from 1/8 to 3/8 inch (0.3 to 1.0 cm).
20. The method of claim 17, wherein the dimensions of each weight
bearing pad are from 1 to 3 inches (2.5 to 7.6 cm) wide, 7 to 11
inches (17.8 to 27.9 cm) long, and 1/8 to 3/8 inch (0.3 to 1.0 cm)
deep.
21. The method of claim 12, wherein each weight bearing pad is
level.
22. The method of claim 12, wherein each weight bearing pad has a
slope.
Description
[0001] This application is a continuation of U.S. Ser. No.
12/266,951, filed Nov. 7, 2008, which claims the benefit of U.S.
Provisional Application No. 60/986,483, filed Nov. 8, 2007,
entitled "Wall Block With Weight Bearing Pads and Method of
Producing Wall Blocks", the contents of each of which are hereby
incorporated by reference herein.
FIELD OF THE INVENTION
[0002] The present invention relates generally to concrete wall
blocks. More particularly the invention relates to wide or
oversized wall blocks having weight bearing pads and to compression
head assemblies used during the process of manufacturing the wall
blocks from a mold.
BACKGROUND OF THE INVENTION
[0003] Numerous methods and materials exist for the construction of
retaining walls and landscaping walls. Such methods include the use
of natural stone, poured in place concrete, masonry, and landscape
timbers or railroad ties. In recent years, segmental concrete
retaining wall units which are dry stacked (i.e., built without the
use of mortar) have become a widely accepted product for the
construction of retaining walls. Such products have gained
popularity because they are mass produced, and thus relatively
inexpensive. They are structurally sound, easy and relatively
inexpensive to install, and couple the durability of concrete with
the attractiveness of various architectural finishes.
[0004] It is desirable to build a wall from such blocks quickly and
without the need for special skilled labor. The efficiency of
building a wall can be measured by determining how fast the front
face of a wall is constructed. Clearly, this depends on the size of
the blocks used and ease of stacking the blocks.
[0005] It is standard practice in the prior art to use similarly
sized mold boxes to produce various styles of block. For example,
U.S. Patent Application Publication No. 2005/00161106 A1 entitled
Method of Making Wall Block, the entirety of which is incorporated
herein by reference, describes a standard size mold box of about 18
inches by about 24 inches (about 45.7 cm by about 61 cm), and about
8 inches (20.3 cm) deep. This standard size mold box is used to
produce blocks of varying sizes. Since those blocks are typically
formed in the mold with their front faces positioned along the 18
inch (45.7 cm) dimension these blocks have a front face with a
dimension of 18 inches by 8 inches and a surface area of about one
square foot (929 sq cm). The '106 application describes an
improvement whereby two blocks are made in a standard size mold box
with the front faces of the blocks formed along the 24 inch (61 cm)
dimension. Those prior art blocks described in the '106 application
are shown in FIG. 1. The blocks 10 are shown as they are formed
within a mold box 20 and each has a front face that is about 24
inches by 8 inches (45.7 cm by 20.3 cm) and an area of about 1.33
square feet (0.124 square meter). This is larger than typical prior
art blocks formed two at a time in the same size mold box which
have a front face area of one square foot (0.0929 square meter). A
larger front face is advantageous because more useable wall surface
area is produced each mold cycle and wall construction speed and
efficiency is increased because it takes fewer blocks that must be
handled and aligned by laborers to build the same size wall.
[0006] During the block molding process the mold box is used to
form multiple blocks at one time. The mold and a lower plate or
production pallet form a cavity for the formation of blocks.
Moldable material such as concrete having a composition well known
to those of skill in the art is placed into the mold and allowed to
set for a time sufficient to allow retention of block shape when
the material is removed from the mold box. Often the blocks are
formed in the mold box with their lower surface facing up and their
upper surface facing down and resting against the pallet. Unless
otherwise noted, that is the block orientation which is used in
this application. As is well known in the art the material is
removed with the aid of a compression head assembly which is
lowered from above the mold box and urges the material out of the
mold. Once the material is removed from the mold the material in
the form and shape of a block or blocks is moved to a curing
station where the blocks are allowed to cure while resting on the
pallet. Another pallet is positioned under the mold to receive the
moldable material which again fills the mold. In this way, many
sets of multiple blocks are formed with one mold and many
pallets.
[0007] During the block molding process it is important that the
blocks are made of a uniform and consistent shape and size and that
block dimensions, especially block height or thickness, are
maintained within acceptable tolerances. This is important for all
blocks but especially those made for use in dry stacked walls.
There are various ways that the acceptable range of tolerance of
block dimensions can be exceeded during the block molding process.
Excessive wear or misalignment of the equipment and machinery used
in the manufacturing process can result in the production of blocks
having one or more dimensions that do not fall within acceptable
tolerances. For example, irregularities in height can be the result
of the blocks being formed on production pallets which have
irregular surfaces. Production pallets can be made of various
materials including steel, plastic and wood. Any irregularity in
the surface of the production pallet will be imparted to blocks
formed on that surface. Although this application focuses on
problems caused by the use of fatigued and sagging production
pallets it should be understood that the concepts disclosed herein
are generally applicable to control tolerances and especially
height/thickness tolerances of any wall block caused by any
reason.
[0008] The size of a typical production pallet used in the block
molding process is from 18 inches by 26 inches (46 cm by 66 cm) for
the smallest pallet to 44 inches by 55 inches (112 cm by 140 cm).
When the pallets are new the surface upon which the blocks are
formed and cured is planar and level. The block surface resting
against the pallet (typically the top surface of the block) is also
planar and level since it assumes the contour of the surface of the
pallet upon which it cures. However, older pallets which have been
used in many production cycles can begin to sag. A block which is
formed and cured on a sagging pallet or on a pallet having an
irregular surface for other reasons will assume the contour of the
pallet. Thus, the block will be formed with a top surface which is
not planar. It is desirable that the dimensions of blocks made
during this process are maintained within acceptable tolerances and
that surfaces which are meant to be level are, in fact, level. This
is especially true of blocks which are made with the intention that
they will be dry stacked. In a wall where the blocks are connected
with mortar it is possible to correct for misshapen blocks (blocks
which do not fall within acceptable tolerances) by using more or
less mortar. However, such correction is not possible in a dry
stacked wall. If the blocks are small and the walls constructed
with the blocks are not too high irregularities in block height
created during the molding process may not affect use of the
blocks. However, the problem is amplified in larger, wider blocks
and blocks used to construct very tall walls. As discussed
previously, the size and width of blocks varies depending on the
size of the mold and the orientation of the blocks in the mold. For
example, the width of blocks may range from less than one foot to
two feet.
[0009] FIG. 2A is a front view of a prior art block 10a similar to
those shown in FIG. 1. Block 10a is shown resting on a level pallet
30 while it cures. It can be seen that the top surface of block 10a
which rests on the pallet is level. FIG. 2B is a front view of
block 10b which is similar to the blocks shown in FIG. 1 except it
is resting on a sagging pallet 40 while it cures. The drawing,
which is somewhat exaggerated to make the concept clear, shows that
the pallet may sag by a distance d which has been measured to be
between about 1/8 inch to 3/32 inch (0.3 cm to 0.2 cm) at each end
on pallets that have been in use for some time. The top surface of
block 10b, which rests against the pallet, is formed with a curve
or bow which results in the thickness of the block being greater at
the center portion of the block than at the ends. This curve or bow
in the block corresponds to the sag of the pallet causing the
middle portion of the top surface to be higher than the ends by
between about 1/8 inch to 3/32 inch (0.3 cm to 0.2 cm).
[0010] FIG. 3A shows a portion of a wall constructed with blocks
10a formed on a level pallet as shown in FIG. 2A. FIG. 3A shows
that the thickness of the blocks is uniform and the tops and
bottoms of the blocks in each course are level. The bottom surface
of blocks in each course of blocks in the wall abuts against the
top surface of the blocks in the next lower course without any gaps
or areas of concentrated stress. This is the situation which is
desired when the blocks are formed. FIG. 3B shows a portion of a
wall constructed with blocks 10b formed on a sagging pallet as
shown in FIG. 2B. This drawing is not to scale but is exaggerated
to clearly show the increased block thickness at the middle portion
of the blocks. The raised middle portion of the top surface of the
blocks 10b is clearly visible. Unlike the wall of FIG. 3A the wall
in FIG. 3B has areas of concentrated stress S at the top middle
portion of each block in a lower course of blocks. The stress areas
S are created where the raised middle portion of the top surface of
the blocks contacts the blocks in the course of blocks above. FIG.
3B also shows that the portion of the block immediately below the
areas of stress do not contact the blocks in the course below
because that location is directly above the end portions of blocks
in the lower course when the wall blocks are placed in a running
bond pattern which is common when building landscape or retaining
walls. The blocks are thinner at the end portions resulting in gaps
between courses at those locations. Since there are gaps between
the courses of blocks directly under the areas of concentrated
stress there is no support provided by the underlying course of
blocks at those areas. The result is that when the height of the
wall is enough to create a downward force at the areas of
concentrated stress S greater than the strength of the block to
resist that stress without support from below a crack C can
develop. The number of cracks which form in the face of the wall
depends on the size of the blocks, the amount of the sag or
curvature or thickness variation of the blocks, and the height of
the wall. Cracks in the wall make the wall less aesthetically
pleasing and, in extreme cases, if there are enough cracks can even
affect the structural integrity of the wall.
[0011] Accordingly, there is a need in the art to compensate or
correct for the dimensional intolerances which are created for
various reasons during the block molding and curing process.
SUMMARY OF THE INVENTION
[0012] The present invention is directed generally at masonry wall
blocks having weight bearing pads on an upper or lower surface and
to methods of making such blocks. In one embodiment the invention
is a wall block having a plurality of weight bearing pads on an
upper or lower surface of the block. In another embodiment the
invention is a compression head assembly having tamper heads which
are used to form weight bearing pads on the upper or lower surface
of a wall block during the block molding process. The invention
also includes the blocks made with the compression head assembly
and walls made from those blocks. The invention also includes a
method of constructing a block wall from the blocks made from the
compression head assembly. The invention also includes a method of
leveling a surface of a block during the block forming process.
This method includes measuring the block specifications during the
forming process and removing material from a surface of the block
or a portion of a surface of a block to level that portion of the
surface of the block.
[0013] The invention provides a wall block comprising a block body
having opposed front and rear faces, opposed first and second side
surfaces, and opposed and substantially parallel upper and lower
surfaces, at least one weight bearing pad extending from one of the
upper and lower surfaces. In one embodiment, the weight bearing pad
extends from the lower surface. In an embodiment, the block body
comprises two weight bearing pads, and in another embodiment the
block body comprises just two weight bearing pads. In an
embodiment, the at least one weight bearing pad extends
substantially from the rear face to the front face of the block
body. In an embodiment, the at least one weight bearing pad is a
rectangular prism. In one embodiment, the at least one weight
bearing pad has a height of from 1/8 to 1/2 inch (0.3 to 1.3 cm),
and in another embodiment the at least one weight bearing pad has a
height of from 1/8 to 3/8 inch (0.3 to 1.0 cm). In an embodiment,
the dimensions of the at least one weight bearing pad are from 1 to
3 inches (2.5 to 7.6 cm) wide, 7 to 11 inches (17.8 to 27.9 cm)
long, and 1/8 to 3/8 inch (0.3 to 1.0 cm) deep. The at least one
weight bearing pad can be level or have a slope.
[0014] The invention provides a compression head assembly for use
in making wall blocks comprising: a stripper shoe including a
bottom portion having at least one opening; and at least one
adjustable tamper head sized to be accommodated within the at least
one opening in the stripper shoe. In an embodiment, the at least
one adjustable tamper head can be raised and lowered relative to
the stripper shoe. In an embodiment, the at least one adjustable
tamper head can be set at an angle relative to a horizontal plane
of the stripper shoe. In one embodiment, the at least one
adjustable tamper head can be set at an angle of from 0 to 5
degrees.
[0015] The invention provides a compression head assembly for use
with a mold in making wall blocks comprising a stripper shoe
including a bottom portion for contacting a wall block surface in
the mold, the bottom portion having at least one indentation for
imparting to the wall block surface at least one raised weight
bearing pad.
[0016] The invention provides a method of making a plurality of
retaining wall blocks comprising providing a mold assembly
including a pallet, a compression head assembly, a mold box having
at least one mold cavity having an open mold cavity top and an open
mold cavity bottom, the mold cavity being shaped to form a single
retaining wall block, each retaining wall block having opposed
front and rear faces, opposed first and second side surfaces, and
opposed and substantially parallel upper and lower surfaces, and at
least one weight bearing pad extending from one of the upper and
lower surfaces, the compression head assembly comprising a stripper
shoe including a bottom portion having at least one opening and at
least one adjustable tamper head sized to be accommodated within
the at least one opening in the stripper shoe; positioning the
pallet beneath the mold box to enclose the mold cavity bottom;
filling the mold cavity with dry cast concrete; lowering the
compression head assembly to enclose the open mold cavity top and
compress the dry cast concrete within the mold cavity, the at least
one weight bearing pad being formed adjacent the at least one
adjustable tamper head; and lowering the pallet and the compression
head assembly to strip the dry cast concrete from the mold
cavity.
[0017] The invention provides a method of making a plurality of
retaining wall blocks comprising providing a mold assembly
including a pallet, a compression head assembly, a mold box having
at least one mold cavity having an open mold cavity top and an open
mold cavity bottom, the mold cavity being shaped to form a single
retaining wall block, each retaining wall block having opposed
front and rear faces, opposed first and second side surfaces, and
opposed and substantially parallel upper and lower surfaces, and at
least one weight bearing pad extending from one of the upper and
lower surfaces, the compression head assembly comprising a stripper
shoe including a bottom portion for contacting a wall block surface
in the mold, the bottom portion having at least one indentation for
imparting to the wall block surface the at least one raised weight
bearing pad; positioning the pallet beneath the mold box to enclose
the mold cavity bottom; filling the mold cavity with dry cast
concrete; lowering the compression head assembly to enclose the
open mold cavity top and compress the dry cast concrete within the
mold cavity, the at least one weight bearing pad being formed
adjacent the at least one indentation; and lowering the pallet and
the compression head assembly to strip the dry cast concrete from
the mold cavity.
[0018] The invention provides a retaining wall comprising a
plurality of courses of retaining wall blocks including a first
upper course and a second lower course, each retaining wall block
having opposed front and rear faces, opposed first and second side
surfaces, and opposed and substantially parallel upper and lower
surfaces, and at least one weight bearing pad extending from one of
the upper and lower surfaces. In an embodiment, the weight bearing
pads in the first upper course and the second lower course are
vertically aligned. In one embodiment, the weight bearing pad
extends from the lower surface.
[0019] The invention provides a method of leveling a wall block
comprising providing a wall block comprising a block body having
opposed front and rear faces, opposed first and second side
surfaces, and opposed and substantially parallel upper and lower
surfaces, at least one weight bearing pad extending from one of the
upper and lower surfaces; and removing a portion of the at least
one weight bearing pad to make the height of the wall block equal
to an adjacent block in a course of a retaining wall.
[0020] The invention provides a mold box for making first and
second wall blocks comprising first and second opposed end rails
and first and second opposed side rails, the end rails and side
rails together forming a mold box; a divider plate having a first
end connected to the first end rail and a second end connected to
the second end rail, the divider plate dividing the mold box into a
first mold section for forming the first block and a second mold
section for forming the second block; and pin hole molding portions
attached to the divider plate.
[0021] It is to be understood that both the foregoing general
description and the following detailed description are exemplary
and explanatory and are intended to provide further explanation of
the invention as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 is a top plan view of a mold box configuration for
Prior Art blocks.
[0023] FIG. 2A is a front view of the blocks shown in FIG. 1 curing
on a level pallet. FIG. 2B is a front view of the blocks shown in
FIG. 1 curing on a sagging pallet.
[0024] FIG. 3A is a front view of a portion of a wall constructed
with the blocks of FIG. 2A. FIG. 3B is a front view of a portion of
a wall constructed with the blocks of FIG. 2B.
[0025] FIG. 4 is a perspective view of a compression head assembly
having adjustable tamper heads according to a first embodiment of
the invention.
[0026] FIG. 5A is a bottom plan view of the compression head
assembly of FIG. 4.
[0027] FIG. 5B is a bottom perspective view of the compression head
assembly of FIG. 4.
[0028] FIG. 5C is a top perspective view of the compression head of
FIG. 4.
[0029] FIG. 6 is a front view of the compression head assembly of
FIG. 4 positioned over a wall block mold box and production
pallet.
[0030] FIG. 7 is a top view of wall blocks removed from the mold of
FIG. 6 and curing on a pallet.
[0031] FIG. 8 is a perspective view of one of the blocks shown in
FIG. 7.
[0032] FIG. 9 is a front view of a portion of a wall built with
blocks shown in FIGS. 7 and 8.
[0033] FIG. 10 is a front view of a wall block which has been
modified in accordance with a further embodiment of this
invention.
[0034] FIG. 11 is a plan view of a mold box showing a divider
plate.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0035] In this application, "upper" and "lower" refer to the
placement of the block in a retaining wall. The lower surface faces
down, that is, it is placed such that it faces the ground. In
forming a retaining wall, one row of blocks is laid down, forming a
course. A second course is laid on top of this by positioning the
lower surface of one block on the upper surface of another
block.
[0036] The blocks of this invention may be made of a rugged,
weather resistant material, such as concrete. Other suitable
materials include plastic, reinforced fibers, and any other
materials suitable for use in molding wall blocks. The surface of
the blocks may be smooth or may have a roughened appearance, such
as that of natural stone. The blocks are formed in a mold and
various textures can be formed on the surface, as is known in the
art. Although the embodiments described herein are discussed with
reference to a wall block having a front width of 24 inches it
should be appreciated that the invention is equally applicable to
blocks of all sizes including those whose front faces are either
larger or smaller than the ones referenced herein.
[0037] As described above due to worn or misaligned equipment used
in the block manufacturing process various dimensional intolerances
and surface irregularities can be unintentionally imparted to the
block. More specifically as described in connection with FIGS. 1 to
3, production pallets which have gone through numerous mold cycles
tend to fatigue over time and eventually start to sag. A sagging or
otherwise irregular pallet imparts to the blocks the same
dimensional intolerances as are present in the pallet. For many
block styles and especially blocks which are meant to be used only
to construct relatively low walls with few courses of blocks these
dimensional intolerances do not create significant problems because
the buildup of stress in areas of concentrated stress are not large
enough to cause cracks in the wall. However larger blocks, because
of their size, are more affected by these dimensional intolerances.
Further, blocks used to construct large walls with many courses of
blocks are more likely, because of the increased weight of the
blocks used, to develop stresses which can cause blocks in the wall
to crack. The present invention includes various embodiments that
are meant to eliminate or reduce these areas of concentrated stress
that are caused by dimensional intolerances which exist in the
block molding process by forming on an upper or lower surface of
the blocks a weight bearing pad.
[0038] FIG. 4 is a perspective view of a compression head assembly
in accordance with one embodiment of the present invention.
Compression head assembly 100 includes a stripper head plate 102
and a stripper shoe 106 comprising an upper portion 106a and a
lower portion 106b. A plurality of stripper plungers 104 are
attached between the stripper head plate 102 and the upper portion
106a of the stripper shoe. For purposes of illustration a plurality
of tamper heads 108 which may be adjustable in the manner described
further below are shown disconnected from the compression head
assembly 100. When connected the tamper heads are received within
compatible openings in the bottom of the lower portion 106b of the
stripper shoe as best seen in FIGS. 5A, 5B and 5C which are a
bottom plan view of the stripper shoe and bottom and top
perspective views of the compression head assembly, respectively.
The tamper heads are provided for the purpose of forming weight
bearing pads on a bottom surface of blocks which are formed in a
block molding process using the compression head assembly in a
manner which will be described in more detail hereafter.
[0039] The adjustable tamper heads 108 are attached to threaded
shafts 110. Shafts 110 are received in apertures in plates 115.
Plates 115 are connected between plungers 104. The depth that the
tamper heads are received into lower portion 106b is set by
adjusting nuts 112 and 114 to raise or lower shafts 110. Each
tamper head 108 pivots with respect to shaft 110 at pivot point
116. The angle at which the tamper heads pivot or tilt is
adjustable by using set screws 117 and 119 which are threaded into
holes in the upper portion 106a of the stripper shoe. By adjusting
the depth by which set screws 117 and 119 extend into and through
upper portion 106a the angle of the tamper heads 108 can be
adjusted in teeter totter fashion.
[0040] FIG. 6 is a front view of compression head assembly 100
positioned over a mold box 20 and pallet 120 during a block forming
process. As known in the art the stripper shoe is discontinuous to
avoid contact with any core bars or cores that may be used in the
block forming process. Once the mold box has been filled with the
moldable material and the material has been vibration compacted to
hold its shape the compression head assembly is lowered to push the
material out of the mold box. The material in the form of wall
blocks remains on the pallet and is moved to a curing station.
[0041] FIG. 7 is a top view of blocks 200 formed in the process
shown in FIG. 6. Blocks 200 are shown resting on the pallet 120 in
the curing station. The blocks 200 have front faces 210 that can
have any texture and can have a bevel. The blocks also have rear
faces 215. The blocks 200 also have pin holes 220 and pin receiving
cavities 230. Pins are often placed in the blocks in the process of
making a wall. Pin hole mold portions 250 are attached to a divider
plate 260, which is attached to the mold box 20 as shown in FIG.
11.
[0042] Since the bottom surfaces of the blocks are oriented upwards
in the mold, FIG. 7 shows the bottom surfaces of the blocks as they
would be used in forming a wall. The adjustable tamper heads which
are recessed into lower portion 106b of the shoe impart to the
bottom surface of each of the blocks a plurality of raised surfaces
122 which function as weight bearing pads. In this embodiment two
weight bearing pads are formed but it should be understood that the
number and position of the weight bearing pads can be varied. The
amount by which each pad is raised from the bottom surface of the
blocks depends on the extent of curvature or other irregularity
that is imparted to the block by the pallet or other portion of the
mold machinery or equipment. For example, if the pallet is fatigued
and sags at each end by from 3/32 to 1/8 of an inch (0.2 to 0.3 cm)
the adjustable tamper heads can be set to form the weight bearing
pads to extend from the bottom surface of the block by up to 1/4
inch (0.64 cm) or more if desired. During the block forming process
adjustments to the adjustable tamper heads can be made based on
measurements taken from blocks which have been previously made.
These measurements may require that the amount that the weight
bearing pads extend from the blocks be increased or decreased. This
is done by adjusting the amount by which the tamper heads are
recessed into lower portion 106b of the stripper shoe. Further, it
may be desirable to increase or decrease the amount by which the
pads are angled or sloped from the front of the blocks to the back.
This angle may be adjusted in the range of from about 0.degree. to
5.degree.. A perspective view of one of the blocks 200 is shown in
FIG. 8. Although the compression head assembly is shown in the
drawings as including four adjustable tamper heads which form two
weight bearing pads 122 on each block it will be apparent to those
of skill in the art that more or fewer tamper heads could be used
to form more or fewer weight bearing pads on each block depending
on how many blocks are formed in the mold box, the size of the
blocks, use requirements, and on the desired amount of weight
distribution points. Further, although the tamper heads are shown
as being adjustable both in the depth they are recessed into lower
portion 106b and in their slope it should be understood that the
tamper heads could be made adjustable only as to amount of recess
or only as to degree of slope. Further, the tamper heads need not
be adjustable at all. In fact the tamper heads need not be separate
components from the stripper show but may comprise recesses formed
into the bottom surface of lower portion 106b to a depth in the
range of about 1/8'' to 3/8'' (0.3 to 1 cm). Further, although in
the manufacturing process described herein the bottom surfaces of
the blocks face upward in the mold box it is also possible to form
wall blocks with the upper block surface facing upwards so that the
weight bearing pads may be formed on either the upper or lower
block surface depending on how the block is oriented in the
mold.
[0043] FIG. 9 is a front view of a wall constructed in an
overlapped or running bond pattern with the blocks of FIGS. 7 and
8. As can be seen each course of blocks contacts an adjacent lower
course of blocks only at weight bearing pads 122. Thus, the weight
of the blocks from upper courses of blocks is applied only at the
locations of the weight bearing pads 122. The pads are positioned
on the blocks so that these load or stress areas are formed
directly above a weight bearing pad on the underlying block. In
other words, when a wall is formed from the blocks 200 in a running
bond pattern as shown in FIG. 9 the pads in each course align
vertically along lines Y. Since there are no areas of high stress
that do not have underlying support, the problem of block cracking
is eliminated even if the block thickness is not consistent within
an acceptable range as may be caused by worn, misaligned or
irregular equipment or machinery used in the block molding
process.
[0044] FIG. 10 illustrates a further embodiment of the invention
which illustrates a method of leveling a portion of a surface of a
wall block. In this embodiment a block 300 is provided with weight
bearing pads 122. Weight bearing pads 122 are formed in the molding
process using a stripper shoe having a recessed tamper head as
described above. However, for purposes of this embodiment the
tamper heads may be separate components which are adjustable as
described above or they may be recesses formed into the bottom
surface of lower portion 106b for which no adjustment is possible.
They may be recessed by a desired amount, for example, 1/4 inch
(0.64 cm). Once the blocks have been formed with the weight bearing
pads the height of those pads may be adjusted, if necessary, based
on measurements taken after the blocks have been formed. The height
adjustment is made by grinding, planning or otherwise removing a
portion of the weight bearing pads shown as cross-hatched in FIG.
10 so that the block height at those locations is consistent from
block to block. This is advantageous since it is not necessary to
control the height of the block at all locations but only at the
location of the weight bearing pads. In other words, the block need
only be formed with standard sized weight bearing pads which are
then mechanically adjusted if necessary to maintain correct height
tolerance for the block by removing or planning an appropriate
amount of material from only the weight bearing pad. Shims could
also be used in this process.
[0045] Although particular embodiments have been disclosed herein
in detail, this has been done for purposes of illustration only,
and is not intended to be limiting with respect to the scope of the
following appended claims. In particular, it is contemplated by the
inventor that various substitutions, alterations, and modifications
may be made to the invention without departing from the spirit and
scope of the invention as defined by the claims. For instance, the
choices of materials or variations in shapes are believed to be a
matter of routine for a person of ordinary skill in the art with
knowledge of the embodiments disclosed herein. Further, although
the invention has been described in connection with blocks having
height inconsistencies or intolerances due to forming the blocks on
a sagging pallet it should be understood that these inventive
concepts and embodiments are also applicable to control height
tolerances on any block having height inconsistencies caused by any
reason.
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