Underpinning machine

An underpinning machine includes a worktable (11) having a central recess (17) housing one or a pair of underpinning heads (20,21; 120). The or each head has a magazine (18,19) of V-nails or wedges associated with it. In a single head version, the underpinning head (120) is power driven between two stop positions and is capable of operation by a drive plate (27) power operated (28,29) from spaced pneumatic rams disposed below the worktable. In another embodiment, two underpinning heads (20,21) are both selectively positionable within the area of the drive plate (27). The operation of the drive plate therefore automatically operates the underpinning heads whatever their position relative to fixed guides (31,32) of the apparatus which locate framing members (42) to be underpinned. By having the underpinning head indirectly actuated by the drive plate (27), a compact and flexible apparatus is provided and in the twin head version the underpinning heads can be placed very close together since there is no interference between respective drive mechanisms.

This invention relates to an underpinning machine for underpinning joints. 
It was particularly devised for underpinning mitred joints between lengths 
of picture framing but could be used for forming other types of 
underpinned joint, for example between a pair of members in furniture 
manufacture. 
Present day underpinning machines are pneumatically operated. In one form, 
an underpinning head is arranged in line with a pneumatic piston and 
cylinder assembly beneath a work table. The framing members are clamped 
above the work table against a pair of abutments, the pneumatic piston 
cylinder assembly is operated and drives the underpinning head to insert a 
fixing, usually a "V-nail" or wedge of sharp edged metal, into the framing 
material. 
If the framing material is other than a narrow and shallow moulding, it may 
be necessary to insert further wedges. This can be done either by stacking 
the wedges, in other words driving another wedge in at exactly the same 
position for a thick frame or by moving the underpinning head to a 
different position and then driving in a further wedge. Some types of 
framing may require both of these techniques to be used. 
However, where the underpinning head is driven directly by the associated 
pneumatic piston and cylinder assembly, that assembly also has to be moved 
beneath the work table, giving rise to difficulties. 
In order to carry out an underpinning operation, the framing members need 
firstly to be positioned and clamped in place against the abutments. This 
is also done pneumatically. It has been proposed to have a separate 
pneumatic drive to the clamping assembly or to utilise a single drive for 
both clamping and underpinning. Such arrangements have hitherto proved 
complicated. Because of the associated pneumatic equipment, current 
underpinning machines are lacking in versatility and do not allow for fast 
and accurate adjustment to tackle different framing materials or the 
multiple insertion of wedges. 
It is an object of the present invention to provide a new or improved 
underpinning machine which overcomes or reduces some or all of these 
disadvantages. 
Viewed from the first aspect, the invention provides an underpinning 
machine for underpinning a joint in a pair of members, the machine 
comprising a work table having abutment means to locate the members, top 
clamping means adapted to clamp the members during underpinning; and at 
least one underpinning head having operating means mounted below the work 
table which include a power operated drive plate, the underpinning head 
being capable of positional adjustment relative to the abutment means on 
the work table and being capable of being driven by said plate throughout 
a range of such positional adjustment to drive an underpinning wedge into 
said pair of members to underpin them. 
The underpinning machine may have two or more underpinning heads. 
Preferably, each underpinning head is capable of such positional 
adjustment and both heads are operable by the drive plate. 
One or both of the underpinning heads, where more than one is provided may 
be rendered inoperative by selectively actuable disabling means associated 
with the underpinning head. 
The disabling means may comprise a power operated pusher means adapted to 
displace a wedge from a position in which it is capable of being driven by 
the underpinning head to a displaced position in which it is not capable 
of being driven by the underpinning head. Thus, the disabling means does 
not prevent the underpinning head from being operated but merely prevents 
a wedge from being driven by displacing the wedge from the position where 
the underpinning head acts. 
Preferably, the abutment means comprise a pair of abutments, one of which 
is rigidly secured to the work table and the other of which has a slight 
positional adjustment relative to the work table. 
The work table may be provided with alternative securement positions for 
the abutment means to enable the angle between them to be selected from a 
range of angles, for example corresponding to rectangular, hexagonal or 
octagonal frames. 
In a first embodiment of the invention, a single underpinning head is 
provided and is movable between a pair of stop means. In this case, the 
underpinning head is preferably provided with power operated drive means 
to move it between said stop means. 
In a second embodiment, the underpinning machine is provided with two 
underpinning heads, each of which is selectively secured in position 
relative to the work table. 
The top clamping means of the underpinning machine may be a clamping head 
assembly as set out in our prior patent application Ser. No. 9114377.6. 
The or each underpinning head may be fed by wedges supplied by the top 
loading means set out in our prior patent application number 9114378.4.

Referring to the drawings, an underpinning machine illustrated by way of 
example in FIGS. 1-4 of the drawings is provided with a single 
underpinning head. A machine having twin underpinning heads will also be 
described in relation to FIGS. 5-9 but since many of the features are the 
same as those of the single head machine, the single head machine will 
only be described so far as it differs from the illustrated twin head 
machine of FIGS. 5-9. 
The underpinning machine generally indicated at 10 comprises a casing 
including a work table 11, a pneumatic air supply 12 and operating 
controls comprising a pair of switches 13, 14 and a pair of buttons 15, 16 
together with a foot pedal pneumatically linked to the apparatus but not 
shown in the drawings. 
A central recess 17 passes through the work table and receives a pair of 
re-usable magazines 18, 19 of underpinning V-nails or wedges. These 
magazines are preferably as described in our co-pending patent application 
Ser. No. 9114378.4 or may alternatively be single use disposable 
cartridges containing V-nails. 
The underpinning machine 10 is provided with front and rear underpinning 
heads 20 and 21. These are shown in more detail in FIGS. 8 and 9; and 
FIGS. 6 and 7 respectively. The front underpinning head 20 uses V-nails 
which are fed from the magazine 19 with their point foremost. The 
underpinning head 21 uses wedges which are supplied by the magazine 18 and 
which are fed with their limbs forwards. Each magazine is fed by a 
respective conventional pusher system housed below the work table 11, 
which will not be described in detail. 
Each of the underpinning heads 20, 21 is selectively positioned relative to 
the work table. The head 20 is linked to a clamp 22 slidably mounted on a 
slot 23 and provided with a graduated position scale and pointer 9. A 
similar clamping knob 24 in a slot 25 is used for positioning the rear 
underpinning head 21. In the example shown, a small gap 26 is provided 
between the underpinning heads since it is intended to underpin a mitred 
joint in relatively narrow framing material. However, the underpinning 
heads 20, 21 can be moved into contact with each other having an effective 
separation of only 12 mm or can be moved to widely separated positions, at 
which they can be clamped by the arrangement just described. 
Both of the underpinning heads are operated from beneath the work table by 
a power operated drive plate 27 shown in FIG. 3 which is mounted in two 
guides (not shown) located within the housing. The drive plate is raised 
and lowered by a pair of piston and cylinder assemblies 28, 29 acting in 
tandem. The plate 27 is raised and lowered for each underpinning operation 
of the machine at the maximum operating pressure of the pneumatic supply. 
Each time it is raised, both of the underpinning heads 20 and 21 are 
operated. This means that two wedges are driven into the framing material. 
However cycling controls, to be described later, may be used to provide a 
more versatile underpinning arrangement in which either one or the other 
head may be disabled or one head may be operated more than once, depending 
on the type of framing material being used. 
The position of the underpinning heads 20, 21 relative to the work table 
can, as described, be selectively adjusted. However, provided the 
underpinning head lies somewhere in the area of the drive plate 27 as 
indicated by the arrow 30, then the underpinning head will be operated on 
each stroke of the piston and cylinder assemblies 28, 29. 
In order to underpin a pair of frame members, they must firstly be located 
relative to the work table so that the miter is correctly aligned with the 
centre line of the work table recess 17 so that the limbs of the wedges 
correctly straddle the miter intersection. Abutment means are therefore 
provided in the form of a pair of guides 31, 32. The guide 31 is rigidly 
secured to the work table by a pair of fasteners. The guide 32, while 
being firmly secured in place, may be permitted a slight degree of 
adjustment due to the provision of attachment slots beneath the nuts 33. 
This enables accurate frames to be made even where the framing material 
may be slightly warped. 
Alternative fixing holes for the guides 31 and 32 may be provided to enable 
the guides 31 and 32 to be positioned at the correct angle for a different 
type of joint, enabling the apparatus to be used for example for hexagonal 
and octagonal frames as well as rectangular frames. 
When the frame members have been placed in position against the guides 31 
and 32, they are clamped in position by clamping means which are shown in 
FIG. 2 of the drawings. The clamping means are raised and lowered by a 
pair of piston and cylinder assemblies 35 operating in tandem at opposite 
ends of a yoke 36. A clamping head is mounted by bolting at 37 to the yoke 
36. 
Referring to FIG. 2 of the drawings, this shows the clamping head generally 
indicated at 38 which may be as set out in our prior patent application 
Ser. No. 9114377.6. A support bar 39 has an elongate slot 40. A clamping 
handle 41 enables the support bar 39 to be secured to the yoke 36 at any 
chosen fore and aft position. 
The apparatus is shown in use in FIG. 2 with a pair of framing members 42 
which have been cut to form a miter 43 and presented to the guides 31 and 
32 so as to locate on the centre line of the recess 17 through the work 
table. The yoke 36 can be lowered to bring the clamping head 38 onto the 
top surface of the framing members 42. 
The clamping head 38 comprises a pair of main jaws 44 which act to hold 
down the frame members 42 and squeeze them towards the position 43 of the 
miter and a further spaced abutment 45 which is provided for use to steady 
very broad frame members and prevent them from rocking when the main 
clamping jaws 44 exert pressure on one edge of the member. It will be 
appreciated that, where narrow frame members are provided as shown at 42, 
the further abutment 45 may be discarded or lifted to an inoperative 
position. Both the clamping jaws 44 and the further abutment 45 are 
vertically adjustable for height by adjustment means not illustrated in 
detail. Reference should be made to our prior patent application Ser. No. 
9114377.6 for the details. 
The twin underpinning head apparatus may be arranged to cycle in four 
alternative modes Go be described in more detail. 
______________________________________ 
1. Set Clamp 
Clamping head lower pedal operation 
Clamping head lift pedal operation 
2. Manual Mode 
Clamping head lower pedal operation 
Insert rear wedge left hand button 
Insert front wedge right hand button 
Clamping head lift pedal operation 
3. Auto Cycle 
Clamping head lower pedal operation 
Insert rear wedge automatic 
Insert front wedge automatic 
Clamping head lift automatic 
Reset cycle pedal operation 
4. Auto Cycle and Manual 
Clamping head lower pedal operation 
Insert rear wedge automatic 
Insert front wedge automatic 
Insert further rear wedge 
left hand button 
Insert further front wedge 
right hand button 
Clamping head lift pedal operation 
______________________________________ 
The modes 1 to 4 are selected by means of two two-position switches 13 and 
14 previously referred to. The left hand and right hand buttons 15 and 16 
are used to control the underpinning heads 20 and 21 respectively but can 
only be operated in modes 2 and 4. No underpinning takes place in mode 1 
which is intended simply to ensure that the clamping head 38 is correctly 
adjusted for the type of framing to be used. The clamping pressure can be 
adjusted by pressure regulation means on the pneumatic supply (not 
illustrated). 
In the automatic cycles 3 and 4, it is not necessary to use the left and 
right buttons since underpinning takes place by both the front and rear 
underpinning heads 20 and 21. However, if mode 4 is selected, additional 
wedges can be inserted either at the front or the rear of the frame. In 
this way, the wedges can be "stacked" to ensure sufficient fixing of thick 
framing members. 
In a simplified form of twin head machine, the mode switches may be omitted 
and the pneumatic circuitry simplified so as to provide a single mode of 
operation equivalent to the manual mode referred to above. However it is 
possible to insert a plurality of front or rear wedges by repeated use of 
the left hand button or right hand button. 
It will be appreciated that, as previously described, the drive plate 27, 
on being lifted by the piston and cylinder assemblies 28, 29, operates 
both underpinning heads 20 and 21. Thus, when the left hand button 15 is 
operated in mode 2 to drive the underpinning head 20, the plate 27 is 
caused to lift and would operate the underpinning head 21 under normal 
circumstances. However, the non-operation of the right hand button 16 
causes selective disabling of the head 21 so that no wedge is driven. 
This disabling takes place by means of a disabling lever means 9 mounted in 
each of the underpinning heads. Each disabling lever means 9 has an 
individual pneumatic actuator. It bears on the foremost wedge or the 
magazine containing the wedges to slightly displace the foremost wedge 
from a position in which the blade of the underpinning head can strike it 
as the underpinning head is operated. 
The individual underpinning heads of the twin head machine shown in FIG. 5 
are illustrated in more detail in FIGS. 6-9. 
The rear underpinning head is shown in FIGS. 6 and 7 and comprises a pair 
of mating blocks 100, 101 having profiled surfaces illustrated in more 
detail in FIG. 6. A bifurcated blade 102 provided with a wedge engaging 
striker edge 103 is arranged to be forced upwardly by the drive plate 27 
of the apparatus on each underpinning operation. It will be seen from the 
assembled view in FIG. 7 that a slight clearance exists between the edge 
103 and the seating 104 provided for the foremost underpinning wedge. 
However in general, when the wedge is being pushed forward by the 
conventional feed means of the apparatus, the edge 103 strikes the wedge 
and drives it into the framing. The disabling lever means 9 operate in the 
slots 105 so as to push the foremost wedge against the seating 104 out of 
range of the edge 103 of the striker as it is raised by the drive plate. 
Alternatively, the lever means 9a can operate in the central slot 106. 
The front head shown in FIGS. 8 and 9 operates in a precisely similar way 
and the same reference numerals have been used. However, in this case only 
the outer slots 105 are provided and there is no equivalent of the 
alternative inner slot 106 for the disabling lever means 9a. 
In order to operate the machine as a single head machine it is simply 
necessary to remove the magazine of underpinning wedges. 
However a single head machine will now be described with reference to FIGS. 
1 to 4, so far as it differs from the twin head machine. 
Firstly, there is no equivalent of the head 21 or its associated top loader 
magazine 18. The underpinning head 20 is replaced by a movable head which 
is power driven along the central recess 17 by a head moving piston and 
cylinder assembly (not shown), the head moving between a pair of end 
stops. These are arranged to be adjusted by clamps and scales 122, 123, 
124, 125. 
The machine cycles in a similar way to the twin head machine previously 
described except that the left and right hand buttons no longer control 
operation of front and rear underpinning heads but now control movement of 
the single underpinning head to the front stop position and rear stop 
position. The rising drive plate arrangement 27 previously described 
continues to function to drive the underpinning head at whichever position 
it occupies. 
It will be appreciated that there is no longer any need for the disabling 
lever means to be provided. 
A simple form of underpinning head can be used in the single head machine 
and this is illustrated in FIG. 4 of the drawings. The underpinning blade 
150 has a generally pentagonal cross-section main body carrying a central 
circular cross-section pin 151 which is telescopically mounted with 
respect to the blade 150. The pin 151 is spring loaded into an upwardly 
extended position in normal operation in which it contacts the underside 
of the framing members to be underpinned. V-shaped wedges are fed in the 
direction of the arrow 152 from a magazine as previously described, the 
magazine being omitted for clarity. The foremost wedge is fed until it 
abuts the circular pin 151 and is held in that position by the pressure of 
the succeeding wedges in the magazine. 
When the drive plate 27 is operated, the blade 150 is forced upwardly. 
However the pin 151 is constrained by the framing members being 
underpinned and does not move relative to them. It therefore telescopes 
inside the blade 150 as it rises, releasing the wedge which is struck by 
the V-shaped striker edge 153 of the blade 150 and driven into the framing 
member. 
Thus, there is no closely fitting location for the V-nail or wedge being 
driven. It is merely located between the pin 150 and the remaining wedges 
in the magazine so that there is no danger of the wedge jamming under 
adverse conditions, as may occasionally occur with other forms of 
underpinning head. 
Further, if the apparatus is actuated without framing members in position 
to restrain the pin 151, the rising blade 150 merely strikes the column of 
wedges emanating from the magazine and may break off a number of these but 
cannot jam them in the apparatus. A head of this type can be substituted 
for the rear head shown in FIGS. 6 and 7 of the twin head machine. 
It will be seen that in both the previously described embodiments of the 
machine, considerable flexibility is allowed by the fact that the 
underpinning head or heads is or are driven by the rising drive plate. 
Thus, the drive to the underpinning head or heads remains in a stationary 
position and can be firmly bolted to the work table 11 whilst allowing for 
considerable positional adjustment of the underpinning head or heads, even 
bringing twin heads very close together. 
In both the single and twin head machines, the different modes of operation 
allow the operator to provide exactly the correct underpinning for any 
particular type of framing member, allowing a single wedge or a plurality 
of wedges to be inserted at a range of separations from very close to 
quite widely separated, and also allowing wedges to be stacked at a single 
insertion position if desired. 
The separation of drive to the clamping means and to the underpinning head 
or heads also enables the machine in one form to provide a non-operational 
mode, mode 1, to be used for setting the top clamp without danger of the 
operator inadvertently operating the underpinning head or heads. Similarly 
this separation of drive allows for the manual operation of the 
underpinning head or heads in modes 2 or 4. 
In use, either version of the machine can be set up to work with a 
particular type of framing member very rapidly, by use of the adjustable 
clamps 22 and 24 and their associated scales. The operator can note the 
scale position for each clamp which is associated with a particular type 
of framing member and set up the underpinning machine appropriately. 
Similarly, the positioning of the top clamping means 38 can readily be 
adjusted so as to hold the framing members securely at the correct 
position for underpinning, using the first "set clamp" mode.