Feeder For Veneer Crowder

Abstract

An apparatus and method for feeding and for joining wood sections to form a wide sheet material is provided. The feeder apparatus, which is used in conjunction with a veneer crowder device, includes means to detect the wood sections both at the beginning of the conveyor which carries them to the crowder and at the crowder itself. If the wood sections are too close together when entering the crowder or have a width dimension greater than a predetermined value, means are actuated by one detector to stop the advance of the other wood sections on the conveyor until the entrance to the crowder is cleared. When a larger gap than desired is present between wood sections placed on the conveyor, such is detected and the conveyor is stopped until the gap is overcome. In this manner, minimum and maximum spacing between wood sections is regulated.

Description

FIELD OF THE INVENTION

This invention relates to the production of sheets of wood from wood sections such as wood veneers and more particularly, to an apparatus for joining such wood veneers to form a composite sheet.

Wood veneer is an important product for use in many industries such as the building construction and plywood manufacturing industries. However, this product is not easily obtainable in a usable form, that is, as a wide, elongated sheet, since it is not readily recoverable in an unmarred state from a peeler log. As a result, several methods have been developed for joining narrow width veneer sections to form a wide sheet. One relatively common method involves the expedient of edge gluing the sections together.

The edge gluing method generally employs a basic unit which is well-known in the industry as a crowder. The crowder functions to move individual pieces into a firm edge-to-edge abutment and to maintain the veneer pieces in this relative position until an adhesive joint is effected. The crowder may be of several types but usually comprises several sets of endless chains aligned vertically. The wood sections are passed along one set of chains and beneath the superimposed chains. The chains are arranged so as to partially retard the movement of the wood sections so that they may be joined edge-to-edge and are generally structured so as to hold the edge-joined veneers in a tight or pressured manner.

In view of the importance of the crowder to a proper edge gluing operation, care must be exercised to ensure that the actual joining of veneer pieces is effected in the crowder section. Premature contact between pieces, that is, prior to the crowder, results in overlap and buckling which seriously affect the quality of the end product. On the other hand, if large gaps exist between veneer sections entering the crowder, proper abutment is not achieved causing gaps and poor bonds between adjacent veneers in the wood sheet. Thus, it is imperative that the veneer sections be fed to the crowder at properly spaced intervals. Since the sections are normally placed on a conveyor which leads to the crowder, manual placement at the beginning of the conveyor must be laboriously carried out if exact spacing is desired. Automatic placement on such a conveyor at timed intervals is unavailing due to the wide variation in the widths (as measured in the direction of travel along the conveyor toward the crowder) of the veneer sections.

It is therefore obvious that in the edge gluing and similar methods of joining veneer sections to form a sheet material there is an important need for an improvement in the manner in which the wood sections are spaced prior to being joined. It is the principal objects of this invention to provide such an improvement by means of an apparatus which efficiently, inexpensively and automatically properly spaces and joins the veneer sections.

Broadly, the present invention is directed to an apparatus for automatically providing suitable spacing between wood sections which are conveyed to the crowder mechanism. The apparatus includes detecting means for sensing the presence of the sections on the conveyor leading to the crowder and for detecting the width dimension of the veneer sections in the direction of travel. Means to remove the sections from the conveyor in response to a signal from the detecting means and for returning the sections to the conveyor in the absence of such a signal are also included. The signal is transmitted when there is improper spacing between sections or in the preferred embodiment, when the width dimension of a section exceeds a predetermined value. Additional detecting means are positioned at the beginning of the conveyor to detect the initial spacing between sections, thereby further regulating the spacing.

More particularly, the detecting means comprising at least two spaced detectors, is positioned at the beginning of the crowder along the conveyor and detects wood sections entering the crowder. If the wood section has a width dimension sufficient to be detected by both detectors simultaneously, a signal is generated to actuate mechanism which removes the remaining wood sections from the conveyor until the detected section passes into the crowder, that is until its trailing edge passes the first positioned detector along the conveyor. In this manner, all wood sections are joined only in the crowder and premature abutting is avoided. The same signal is generated if the detectors sense two different wood sections at the same time. This would occur if there is a backup of sections in the crowder area or, as another example, if a short wood section not sufficient in length to be detected by both detectors, is closely followed by a second wood section. In all such situations, the remaining wood sections would be prevented from proceeding along the conveyor until the immediately preceding section has entered the crowder.

To avoid the problems encountered when the wood sections are not fed quickly enough to the conveyor, second detecting means is positioned near the beginning of the conveyor and is connected to the motor which drives the conveyor. If no wood section is detected at the beginning segment of the conveyor, the motor is caused to stop and thus the entire apparatus is essentially immobilized. Thus, no excessive gap can exist between wood sections entering the crowder since the feed rate of wood sections is also automatically monitored. Therefore, in the preferred embodiment of the invention, both maximum and minimum gaps or spacing between articles are regulated.

DESCRIPTION OF THE DRAWINGS

The invention will be further explained in conjunction with the drawings wherein:

FIG. 1 is a schematic view of the wood joining apparatus of the invention;

FIG. 2 is a perspective view of part of the apparatus shown in FIG. 1;

FIG. 3 is a detail view of a mechanism for automatically regulating the travel of veneer sections; and

FIG. 4 is a detail end view of the apparatus illustrated in FIG. 2.

Referring to the drawings, there is shown in FIG. 1 a wood joining apparatus designated generally by the numeral 10. The apparatus includes a conveyor 12 which comprises an endless chain 14 revolving around sprockets 16, 18. A crowder is schematically illustrated at 20 and includes endless chain 22 which revolves about sprockets 24, 26. The crowder 20 is depicted in a simplified form to typify the well-known types of this mechanism. A detecting means 28 comprising two detectors 30, 32, spaced a distance designated by the letter a, is positioned proximate the beginning of the crowder mechanism. A second detecting means 34 is placed near the beginning of the conveyor 12 and includes a plurality of detectors 36, 38 and 39, the distance between detectors 36 and 39 being marked by the letter b. A bar 40 which is shown in a raised position, that is, higher in elevation than the conveyor 12, supports wood sections 42, 44. Wood section 46 is shown just entering the crowder 20 below sprocket wheel 24 and is positioned over both detectors 30, 32. Wood sheet 48, positioned within the crowder section, is composed of a plurality of joined wood sections 50, 52, 54.

In the operation of the system, conveyor 12 and crowder 20 are driven by motor means, and endless chains 14 and 22 rotate in a direction so as to advance the wood sections along the conveyor and through the crowder. The bar 40 is normally in a lowered position, that is, below the conveyor 12 and does not interfere with travel of the wood sections. However, if a wood section having a width greater than the distance a, such as section 46, enters the crowder 20, detectors 30, 32 are both actuated and generate a signal to cause the bar 40 to remove from conveyor 12 all wood sections prior to wood section 46 as shown. Conveyor 12 is still operative, however, and when the trailing edge of section 46 passes detector 30, the bar 40 is lowered and sections 42, 44 proceed on the conveyor toward the crowder. The interrupted movement of wood sections ensures a proper spacing at the entrance to the crowder (as shown by numeral 56) when a wide piece of wood, i.e., having a width greater than the predetermined distance a, passes into the crowder or when two sections less than the distance a enter the crowder together as hereinbefore explained. In these situations, the minimum spacing between trailing sections will be measured by the dimension c which is the distance between the end of the bar 40 and the detector 30. Detecting means 34 issues a signal only when none of the detectors 36, 38, 39 senses the presence of a wood section on the conveyor, that is, when the wood sections are placed on the conveyor so infrequently as to have a gap between them greater than the distance b. In this situation, the issued signal stops the conveyor 12 or crowder 20 until detecting means 34 once again detects a wood section. In this manner, a gap or space between sections of no greater than the distance b is automatically achieved.

In FIG. 2, the apparatus of FIG. 1 is shown in perspective. As there shown, several chains 14 carry the wood sections toward the crowder 20. The bars 40 are secured to the shafts 58, 60. Means for lifting the bar to its raised position are partially illustrated at 62, 64 in FIG. 2 and shown in detail in FIG. 3. The detectors 36, 38, 39 are spaced along the path of travel of the veneer sections and are, in this embodiment, photoelectric scanners which are commonly known as "electric eyes." They are positioned below the conveyor and sense wood sections passing through the emitted light beam which is directed toward the conveyor. While this type of device has been employed quite successfully, it will be appreciated that any number of detecting devices such as sonic detectors, mechanical limit switches and the like would be equally suitable for detectors 28 or 34 shown in FIG. 1.

In FIG. 3, one means for lifting the bar to contact and remove wood sections is illustrated. The devices 62 and 64 are substantially similar and include bellcranks 66, 68, respectively, which are in contact with the rod 40 and the shafts 58, 60. Each device is provided with a crank arm 70, 72 movably secured to the bellcranks. Crank arm 70 is connected through segment 74 to air cylinder 76 while crank arm 72 is connected to spring 78 by segment 80. A bellows 82 communicates through air lines with air cylinder 76 and valve 84. Mounting bracket 86 provides support for the air cylinder and bellows.

During the operation of the system, wood sections pass into the crowder 20 as hereinbefore described and over the photoelectric scanners 30, 32. When both of these detectors sense a wood section, an electrical signal is transmitted to valve 84. Bellows 82 and cylinder 76 then function to reposition piston 88 which causes crank arm 70 and bellcrank 66 to move such that bar 40 is raised. This motion causes spring 78 to force bell crank 68 to exert a pressure on bar 40 through crank arm 72. The bar is then maintained in this position until either of the detectors no longer senses a wood section. Reverse flow of air is then effected through the components 76, 82, 84, and piston 88 is returned to its original position, thereby causing the bar to be lowered to its normal position. The cycle is repeated each time the detector 28 generates a signal to actuate the bar-lifting mechanism.

FIG. 4 illustrates a front elevation view of the apparatus shown in FIG. 2. The shaft 58 functions to support the bars 40 through lifting means 62 and to assist in activating the several bars simultaneously. As depicted in the drawing, a plurality of bars can be placed on the shaft at spaced intervals to facilitate the removal of the veneer sections from the conveyor. By way of example, in one apparatus seven bars 1 inch wide were spaced 21 inches apart along a 1-inch diameter shaft. The total span of the apparatus was 132 inches as measured along the shaft 58.

The desired spacing between veneer sections can be predetermined as hereinbefore explained by proper spacing of the various detectors. In one successful application of the apparatus of the invention, two photoelectric scanners were placed at the beginning of a crowder mechanism substantially as shown in FIG. 1 and FIG. 3 and were spaced a distance a of 7 inches. An important feature of the invention is that this dimension can be easily adjusted to increase or decrease the sensitivity of the apparatus without the need for costly assembly operations or parts fabrication.

It will be appreciated that a wide variety of modifications of the apparatus of the invention are possible without departing from the scope of the invention. For example, the conveyor need not be endless chains as illustrated; rather, any suitable conveying means which will effectively carry the veneer sections to the crowder is acceptable for the purpose of the invention. In addition, the means to remove the veneer sections from the conveyor can readily be modified to operate equally well with functionally equivalent components. Broadly, any means which will prohibit the relative movement of the wood sections to the crowder will be suitable for the invention.

From the foregoing, it is obvious that the apparatus of the invention provides a simple, economical and effective solution to the long standing problem of proper spacing of veneer wood sections which are joined in an edge gluing or similar operation. Exactness on the part of the operator of the apparatus is no longer required since minimum and maximum spacing is predetermined and automatically regulated.

An apparatus and method for feeding and for joining wood sections to form a wide sheet material is provided. The feeder apparatus, which is used on conjunction with a veneer crowder device, includes means to detect the wood sections both at the beginning of the conveyor which carries them to the crowder and at the crowder itself. If the wood sections are too close together when entering the crowder or have a width dimension greater than a predetermined value, means are actuated by one detector to stop the advance of the other wood sections on the conveyor until the entrance to the crowder is cleared. When a larger gap then desired is present between wood sections placed on the conveyor, such is detected and the conveyor is stopped until the gap is overcome. In this manner, minimum and maximum spacing between wood sections is regulated.

It is therefore seen that there has been invented a continuous or intermittent feeder deice and method which can be controlled by any conventional and suitable sensing means, such as electric eyes, sonic detectors, mechanical limiting switches, etc. This method for feeding veneers which have previously been glues (and remain tacky) along both of its longitudinal contacting edges will form into a single solid sheet of veneer when the faster moving conveyor means 14 carries veneers into intimate firm contact with the preceeding veneer slowed down by the slower moving and controlling conveyor 20. The feeder may be used in combination with only jointed and edge glued edges or with only string machines such as disclosed in Osgood, U.S. Pat. No. 1,977,199, and Clausen, U. S. Pat. No. 3,377,223, or with both edge gluing and tying strings.

Claims

I claim:

1. An apparatus for spacing wood sections which are to be joined to form a composite wood sheet comprising: conveyor means for moving said sections to a position where they are to be joined; detecting means for detecting when the width dimension of a leading wood section on said conveyor means exceeds a predetermined value; and means for prohibiting the movement of trailing wood sections toward said position when the width of a leading wood section is detected to be in excess of said predetermined value while said leading section is maintained in motion, and for continuing the movement of said trailing wood sections toward said position when said detecting means no longer detects the excessive width dimension of said leading wood section.

2. The apparatus of claim 1 wherein said detecting means is placed just prior to the position where said wood sections are to be joined.

3. The apparatus of claim 2 wherein a second detecting means is positioned proximate the beginning of said conveyor means to detect the spacing of said sections thereon, and means are provided for stopping said conveyor when said second detecting means detects a spacing between wood sections greater than a predetermined value.

4. In an apparatus for joining wood sections comprising conveyor means for moving said sections to a position to be joined, the improvement which comprises: detecting means for sensing the presence of said sections on said conveyor means, said detecting means comprising at least two spaced detectors; and means for removing said sections from said conveyor means when a section is detected by both of said spaced detectors to thereby stop the movement of all sections behind said detected section, and for returning said sections to said conveyor means when at least one of said detectors does not detect said section, whereby a suitable space between sections is maintained.

5. The apparatus of claim 4 wherein said means for removing said wood sections comprises at least one bar extending substantially parallel to said conveyor and being movably mounted below said conveyor; and means for moving said bar in a direction to contact and remove said wood sections from said conveyor.

6. The apparatus of claim 5 wherein said detecting means comprises at least two spaced photoelectric scanners positioned proximate said conveyor.

7. The apparatus of claim 4 wherein second detecting means for detecting said wood sections is positioned near the beginning of said conveyor; and means are provided for stopping said conveyor when a wood section is not detected by said second detecting means, whereby the spacing between wood sections on said conveyor is further regulated.

8. In combination with a crowder mechanism for joining wood sections in an edge-to-edge abutment, an apparatus for spacing said wood sections prior to being joined in the crowder mechanism comprising: a. conveyor means for advancing said wood sections to said crowder; b. detecting means positioned at the entrance to said crowder means, said detecting means comprising at least two spaced detectors for sensing the presence of said sections to be joined; and c. means for removing said sections from said conveying means when both of said spaced detectors detect at least one wood section to thereby stop the movement of the sections behind said detected section, and for returning said removed sections to said conveyor means when at least one of said detectors does not detect a section, whereby a suitable space between sections to be joined is maintained in the area of said crowder mechanism.

9. The apparatus of claim 8 wherein a second detecting means is positioned proximate the beginning of said conveyor means to detect said sections as they are placed on said conveyor means, said second detecting means being connected to said conveyor means such that if no section is detected thereby, said conveyor means is stopped whereby the spacing of said sections is further regulated.

10. The apparatus of claim 8 wherein said detecting means comprises at least two photoelectric scanners spaced a predetermined distance in the direction of travel of said wood sections.

11. The apparatus of claim 8 wherein said conveyor means comprises a plurality of feed chains and motor means to drive said feed chains.

12. The apparatus of claim 11 wherein said means for removing said wood sections comprises: a. at least one bar extending substantially the distance between the beginning of said conveyor means and said crowder mechanism, said bar being positioned below and between said feed chains; and b. air actuated means for raising said bars so as to contact and lift said wood sections from said conveyor in response to a signal from said detecting means.

13. A combination of a crowder mechanism for joining adjacent wood sections in an edge-to-edge abutment and an apparatus for spacing said wood sections prior to being joined in said crowder mechanism, said apparatus, comprising: a. conveyor means for advancing said wood sections to said crowder mechanism; b. detecting means for detecting when the width dimension of a leading wood section measured along the direction of travel on said conveyor means exceeds a predetermined value, said detecting means being positioned proximate the entrance of said crowder mechanism; c. means for removing trailing wood sections from said conveyor means in response to a signal from said detecting means, and for returning said removed wood sections to said conveyor means in the absence of a signal from said detecting means; and d. said detecting means providing said signal to said removing means when a leading wood section is detected to have a width in excess of said predetermined value, whereby the edge-to-edge abutment of said leading wood section and the succeeding trailing wood section occurs in said crowder mechanism.

14. Method for controlling the movement of short widths of wood veneer into a large continuous sheet of veneer by passing said veneers through a series of detecting devices, raising trailing veneers by lifting means from contact with moving means when the spaces between adjacent leading and trailing veneers is below a predetermined minimum spacing distance and stopping said veneers when the spaces between adjacent veneers exceeds a predetermined minimum spacing.